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

Abstract

In the present disclosure, a method comprises the steps of: configuring a split bearer comprising a first radio path directly connected to a network and a second radio path indirectly connected to the network through a relay UE; and transmitting an RRC (Radio Resource Control) message to the network through the primary path of the split bearer, determining the primary path of the split bearer as the first radio path on the basis that the type of the split bearer is a specific type of SRB (Signaling Radio Bearer) carrying the RRC message when the split bearer is configured.

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. In general, 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 code division multiple access (CDMA) systems, frequency division multiple access (FDMA) systems, time division multiple access (TDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single carrier frequency division multiple access (SC-FDMA) systems, and multi-carrier frequency division multiple access (MC-FDMA) systems.

[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 performing communication by a remote user equipment (UE) in a wireless communication system includes: configuring a split bearer, the split bearer including a first radio path directly connected to a network and a second radio path indirectly connected to the network through a relay UE; and sending a radio resource control (RRC) message to the network through a primary path of the split bearer, when configuring the split bearer, determining the primary path of the split bearer to be the first radio path based on that a type of the split bearer is a specific type of a signaling radio bearer (SRB) carrying the RRC message.

[0020] Preferably, the method further includes receiving an RRC configuration message for configuring a split bearer, wherein the RRC configuration message for configuring a split bearer associated with a specific type of SRB always configures the primary path as the first radio path.

[0021] Preferably, the specific type is SRB1 for a Radio Resource Control (RRC) message using a Dedicated Control Channel (DCCH) logical channel.

[0022] Preferably, the specific type is SRB2 for Non-Access Stratum (NAS) messages using a Dedicated Control Channel (DCCH) logical channel.

[0023] Preferably, the method further includes receiving an RRC configuration message for configuring the split bearer, and determining the primary path of the split bearer as the first radio path based on the RRC configuration message for configuring the split bearer without configuring the primary path.

[0024] Preferably, the method further includes receiving an RRC configuration message for configuring a split bearer, and determining a primary path of the split bearer as the first radio path, regardless of the primary path configured by the RRC configuration message.

[0025] Preferably, the method further includes receiving an RRC configuration message for configuring a split bearer, and adding the first radio path to the remote UE by configuring the split bearer based on the RRC configuration message.

[0026] Preferably, the method further includes receiving an RRC configuration message for configuring a split bearer, and based on the type of the split bearer being a data radio bearer (DRB) type, determining the primary path as the second radio path based on the RRC configuration message.

[0027] Preferably, the method further includes receiving an RRC configuration message for configuring the split bearer, wherein the RRC configuration message is received through the second radio path.

[0028] In another aspect of the present disclosure, there is provided a computer-readable storage medium having stored thereon a program for executing the above method.

[0029] In another aspect of the present disclosure, an apparatus configured to perform the method is provided.

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

[0031] Beneficial Effects

[0032] According to the embodiments of the present disclosure, the wireless signal transmission / reception process can be performed accurately and efficiently. For example, even if the split bearer for the first radio path and the second radio path is configured without indicating the main path, the main path for the split bearer of a specific SRB type can be clearly determined.

[0033] 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

[0034] 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.

[0035] Figure 2 The structure of an LTE system to which the embodiments can be applied is illustrated.

[0036] Figure 3 The structure of an NR system to which an embodiment can be applied is illustrated.

[0037] Figure 4 The structure of an NR radio frame to which an embodiment can be applied is illustrated.

[0038] Figure 5 The time slot structure of the NR frame to which the implementation scheme can be applied is illustrated.

[0039] Figure 6 A radio protocol architecture for SL communications is illustrated.

[0040] Figure 7 A UE performing V2X or SL communication is illustrated.

[0041] Figure 8 Resource units used for V2X or SL communication are illustrated.

[0042] Fig. 9 The inter-UE coordination information MAC CE is illustrated.

[0043] Fig.10 An inter-UE coordination request MAC CE is illustrated.

[0044] Fig.11 (a) User plane protocol stack and (b) control plane protocol stack for L2 UE to network relay are illustrated.

[0045] Fig.12 A protocol stack for UE-to-network relay discovery messages is illustrated.

[0046] Fig.13 The procedure for L2 U2N remote UE connection establishment is illustrated.

[0047] Fig.14 The procedure for U2N remote UE handover to direct Uu cell is illustrated.

[0048] Fig.15 The procedure for U2N remote UE switching to an indirect path is illustrated.

[0049] Fig.16 is a diagram for explaining a method of establishing a U2N bearer for an L2 U2N remote UE and an L2 U2N relay UE.

[0050] Fig.17 is a diagram for explaining a method for configuring a split bearer by a remote UE.

[0051] Fig.18 is a diagram for explaining a method for a remote UE to configure a split bearer for a multipath including a first radio path and a second radio path based on an RRC configuration message.

[0052] Fig.19 A communication system applied to the present disclosure is illustrated.

[0053] Fig. 20 A wireless device suitable for use with the present disclosure is illustrated.

[0054] Fig.21 Another example of a wireless device to which the present disclosure is applied is illustrated.

[0055] Fig. 22 A vehicle or an autonomous driving vehicle to which the present disclosure is applied is illustrated. DETAILED DESCRIPTION

[0056] 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 code division multiple access (CDMA) systems, frequency division multiple access (FDMA) systems, time division multiple access (TDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single carrier frequency division multiple access (SC-FDMA) systems, and multi-carrier frequency division multiple access (MC-FDMA) systems.

[0057] Details of the background, terminology, abbreviations etc. used herein can be found in the following documents.

[0058] 3GPP LTE

[0059] -3GPP TS 36.211: Physical channels and modulation

[0060] -3GPP TS 36.212: Multiplexing and channel coding

[0061] -3GPP TS 36.213: Physical layer procedures

[0062] -3GPP TS 36.214: Physical layer; Measurement

[0063] -3GPP TS 36.300: Overall description

[0064] -3GPP TS 36.304: User Equipment (UE) procedures in idle mode

[0065] -3GPP TS 36.314: Layer 2 - Measurement

[0066] -3GPP TS 36.321: Medium Access Control (MAC) Protocol

[0067] -3GPP TS 36.322: Radio Link Control (RLC) protocol

[0068] -3GPP TS 36.323: Packet Data Convergence Protocol (PDCP)

[0069] -3GPP TS 36.331: Radio Resource Control (RRC) protocol

[0070] 3GPP NR

[0071] -3GPP TS 38.211: Physical channels and modulation

[0072] -3GPP TS 38.212: Multiplexing and channel coding

[0073] -3GPP TS 38.213: Physical layer procedures for control

[0074] -3GPP TS 38.214: Physical layer procedures for data

[0075] -3GPP TS 38.215: Physical layer measurements

[0076] -3GPP TS 38.300: Overall description

[0077] -3GPP TS 38.304: User Equipment (UE) procedures in idle mode and RRC inactive state

[0078] -3GPP TS 38.321: Medium Access Control (MAC) Protocol

[0079] -3GPP TS 38.322: Radio Link Control (RLC) protocol

[0080] -3GPP TS 38.323: Packet Data Convergence Protocol (PDCP)

[0081] -3GPP TS 38.331: Radio Resource Control (RRC) protocol

[0082] -3GPP TS 37.324: Service Data Adaptation Protocol (SDAP)

[0083] -3GPP TS 37.340: Multi-connectivity; general description

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] Figure 3 The structure of the NR system according to an embodiment of the present disclosure is illustrated.

[0096] 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.

[0097] Figure 4 The radio frame structure in NR to which the embodiments of the present disclosure are applicable is illustrated.

[0098] 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).

[0099] 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).

[0100] 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 .

[0101] [Table 1]

[0102] <![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

[0103] 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.

[0104] [Table 2]

[0105] SCS(15*2^u) <![CDATA[N slot symb ]]> <![CDATA[N frame,u slot ]]> <![CDATA[N subframe,u slot ]]> 60kHz(u=2) 12 40 4

[0106] 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.

[0107] 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.

[0108] 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).

[0109] [Table 3]

[0110] Frequency range name Corresponding frequency range Subcarrier Spacing (SCS) FR1 450MHz-6000MHz 15,30,60kHz FR2 24250MHz-52600MHz 60,120,240kHz

[0111] 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).

[0112] [Table 4]

[0113] Frequency range name Corresponding frequency range Subcarrier Spacing (SCS) FR1 410MHz-7125MHz 15,30,60kHz FR2 24250MHz-52600MHz 60,120,240kHz

[0114] Figure 5 The time slot structure in the NR frame according to an embodiment of the present disclosure is illustrated.

[0115] 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.

[0116] 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.

[0117] 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.

[0118] Now, a description will be given of V2X or Side Link (SL) communication.

[0119] 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.

[0120] Next, the side link synchronization signal (SLSS) and the synchronization information will be described.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] 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 resource 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.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] Figure 7 A UE performing V2X or SL communication is illustrated.

[0129] 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.

[0130] 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.

[0131] 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.

[0132] 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.

[0133] Figure 8 Resource units used for V2X or SL communication are illustrated.

[0134] 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.

[0135] 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.

[0136] 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.

[0137] (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.

[0138] (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.

[0139] (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.

[0140] 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.

[0141] SL DRX (Side Link Discontinuous Reception)

[0142] 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.

[0143] The actual parameters supported for each broadcast type (unicast, multicast, broadcast) are specified in the following subsections.

[0144] 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.

[0145] 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.

[0146] For unicast, SL DRX is configured per pair of source L2 ID and destination L2 ID.

[0147] 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:

[0148] - 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.

[0149] - 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.

[0150] - The TX UE sends to the RX UE the SL DRX configuration to be used by the RX UE.

[0151] -RX UE can accept or reject the SL DRX configuration.

[0152] The default SL DRX configuration for multicast / broadcast may be used for DCR messages.

[0153] 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.

[0154] 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.

[0155] The SL DRX MAC CE is introduced only for SL DRX operation in unicast.

[0156] 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.

[0157] 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.

[0158] 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.

[0159] 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.

[0160] 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.

[0161] 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).

[0162] 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.

[0163] 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.

[0164] 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.

[0165] 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.

[0166] RRC controls the sidelink DRX operation by configuring the following parameters:

[0167] -sl-drx-onDurationTimer: duration when SL DRX cycle starts;

[0168] -sl-drx-SlotOffset: Delay before starting sl-drx-onDurationTimer;

[0169] -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);

[0170] -sl-drx-RetransmissionTimer (per-side link process except broadcast transmission): maximum duration until SL retransmission is received;

[0171] -sl-drx-StartOffset: The time slot where the SL DRX cycle starts;

[0172] -sl-drx-Cycle: sidelink DRX cycle;

[0173] -sl-drx-HARQ-RTT-Timer (per sidelink process except broadcast transmission): Minimum duration before SL HARQ retransmission expected by the MAC entity.

[0174] When SL DRX is configured, active time includes the following times:

[0175] -sl-drx-onDurationTimer or sl-drx-InactivityTimer is running; or

[0176] -sl-drx-RetransmissionTimer is running; or

[0177] - the period of sl-LatencyBoundCSI-Report configured by RRC in case no SL-CSI Report MAC CE is received; or

[0178] - 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

[0179] -Time slot associated with periodic transmission announced by the UE sending SL-SCH data.

[0180] When one or more SL DRXs are configured, the MAC entity shall:

[0181] 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:

[0182] 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:

[0183] 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.

[0184] 1> If sl-drx-HARQ-RTT-Timer expires:

[0185] 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:

[0186] 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.

[0187] 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:

[0188] sl-drx-StartOffset (ms) = destination layer-2 ID modulo sl-drx-Cycle (ms).

[0189] sl-drx-SlotOffset (ms) = destination layer-2 ID modulo sl-drx-onDurationTimer (ms).

[0190] 1> If SL DRX cycle is used, and [(DFNX10) + subframe number] modulo (sl-drx-Cycle) = sl-drx-StartOffset:

[0191] 2> Start sl-drx-onDurationTimer after sl-drx-SlotOffset from the start of the subframe.

[0192] 1> If SL DRX is in active time:

[0193] 2> Monitor SCI (ie, first stage SCI and second stage SCI) in the SL DRX.

[0194] 2> If SCI indicates a new SL transfer:

[0195] 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:

[0196] 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.

[0197] 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:

[0198] 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

[0199] 4> After the first timeslot of SCI reception, start or restart the sl-drx-InactivityTimer for the corresponding destination layer-2ID.

[0200] 2> If SCI indicates SL transfer:

[0201] 3> If PSFCH resources are not configured for SL grant associated with SCI:

[0202] 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.

[0203] 3> If PSFCH resources are configured for SL grant associated with SCI:

[0204] 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;

[0205] 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

[0206] 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;

[0207] 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;

[0208] 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

[0209] 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

[0210] 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.

[0211] 4> If HARQ feedback is disabled by SCI and resources for one or more retransmission opportunities are not scheduled in SCI:

[0212] 5> Start the sl-drx-HARQ-RTT-Timer for the corresponding side link process in the time slot after the PSFCH resource ends.

[0213] 4> If HARQ feedback is disabled by SCI and resources for one or more retransmission opportunities are scheduled in SCI:

[0214] 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.

[0215] 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.

[0216] 3> Stop the sl-drx-RetransmissionTimer for the corresponding side link process.

[0217] 1> If a SL DRX Command MAC CE is received for a source layer-2ID and destination layer-2ID pair for unicast:

[0218] 2> Stop sl-drx-onDurationTimer for the source layer-2ID and destination layer-2ID pair for unicast;

[0219] 2> Stop the sl-drx-InactivityTimer for the source layer-2ID and destination layer-2ID pair for unicast.

[0220] Inter-UE Coordination (IUC)

[0221] 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:

[0222] - 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

[0223] - 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.

[0224] 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.

[0225] 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.

[0226] 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.

[0227] The Sidelink Inter-UE Coordination Information (SL-IUC Info) reporting procedure is used to provide inter-UE coordination information to peer UEs.

[0228] -sl-LatencyBoundIUC-Report, which is maintained for each PC5-RRC connection.

[0229] 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.

[0230] 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:

[0231] 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:

[0232] 2> If the sl-IUC-ReportTimer for the triggered SL-IUC information report is not running:

[0233] 3>Start sl-IUC-ReportTimer.

[0234] 2> If the sl-IUC-ReportTimer for the triggered SL-IUC information report expires:

[0235] 3>Cancel the triggered SL-IUC information report.

[0236] 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:

[0237] 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;

[0238] 3> Stop the sl-IUC-ReportTimer for the triggered SL-IUC information report;

[0239] 3>Cancel the triggered SL-IUC information report.

[0240] Fig. 9 The inter-UE coordination information MAC CE is illustrated.

[0241] The inter-UE coordination information MAC CE is identified by a MAC subheader with LCID specified in Table 5.

[0242] [Table 5]

[0243]

[0244] The priority of the Inter-UE Coordination Information MAC CE is fixed to '1'. It has a variable size with the following fields:

[0245] -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.

[0246] -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;

[0247] -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;

[0248] -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;

[0249] -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;

[0250] -R: Reserved bit, set to 0.

[0251] Fig.10 An inter-UE coordination request MAC CE is illustrated.

[0252] 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:

[0253] -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.

[0254] -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;

[0255] - 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;

[0256] -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;

[0257] - 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;

[0258] -R: Reserved bit, set to 0.

[0259] Sidelink Relay

[0260] 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.

[0261] Relay Discovery: The AS functionality enables 5G ProSe UE to network relay discovery, using NR technology but without traversing any network nodes.

[0262] U2N Relay UE: A UE that provides a U2N Remote UE with the functionality of supporting connection to the network.

[0263] U2N Remote UE: A UE that communicates with the network via a U2N Relay UE.

[0264] Upstream: In the IAB topology, in the direction toward the parent node.

[0265] 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.

[0266] A U2N relay UE should be in RRC_CONNECTED to perform relay of unicast data.

[0267] For L2 U2N relay operation, the following RRC state combinations are supported:

[0268] - Both the U2N relay UE and the U2N remote UE should be in RRC_CONNECTED to perform transmission / reception of relayed unicast data.

[0269] - 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.

[0270] For L2 U2N relay, the U2N remote UE can only be configured to use resource allocation mode 2 for the data to be relayed.

[0271] 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.

[0272] Protocol stack for SL relay

[0273] Fig.11 (a) User plane protocol stack and (b) control plane protocol stack for L2 UE to network relay are illustrated.

[0274] 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).

[0275] 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.

[0276] For L2 U2N relay, for uplink:

[0277] - 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.

[0278] - 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.

[0279] -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.

[0280] For L2 U2N relay, for downlink:

[0281] -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.

[0282] - 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.

[0283] - 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.

[0284] - 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.

[0285] 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.

[0286] 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.

[0287] Fig.12 A protocol stack for UE-to-network relay discovery messages is illustrated.

[0288] 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 .

[0289] 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.

[0290] 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.

[0291] 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.

[0292] 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.

[0293] 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.

[0294] 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.

[0295] The sidelink power control used to transmit relay discovery messages is the same as that used for NR sidelink communications.

[0296] No ciphering or integrity protection in the PDCP layer is applied to the Relay Discovery message.

[0297] The UE can determine from SIB12 whether the gNB supports relay discovery, non-relay discovery, or both.

[0298] Relay selection / reselection

[0299] 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.

[0300] 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.

[0301] 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.

[0302] The U2N remote UE triggers the U2N relay selection in the following cases:

[0303] -The direct Uu signal strength of the current serving cell of the U2N remote UE is lower than the configured signal strength threshold;

[0304] - Indicated by upper layers of the U2N remote UE.

[0305] The U2N remote UE can trigger U2N relay reselection in the following situations:

[0306] -The current PC5 signal strength of the U2N relay UE is lower than the (pre-)configured signal strength threshold;

[0307] -Cell (reselection) selection, handover or Uu RLF has been indicated by the U2N relay UE via PC5-RRC signalling;

[0308] -When the remote UE receives a PC5-S link release message from the U2N relay UE;

[0309] -When the U2N remote UE detects PC5 RLF;

[0310] -Instructed by upper layer.

[0311] 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.

[0312] 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.

[0313] Control plane procedures for L2 U2N relay

[0314] 1)RRC connection management

[0315] U2N remote UE needs to establish its own PDU session / DRB with the network before user plane data transmission.

[0316] 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.

[0317] 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.

[0318] 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:

[0319] 1. The U2N Remote and U2N Relay UEs perform the discovery procedure and establish a PC5-RRC connection using NR V2X procedures.

[0320] 2. The U2N Remote UE sends a first RRC message (i.e., RRCSetupRequest) for its connection establishment with the gNB via the Relay UE 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.

[0321] 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.

[0322] 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.

[0323] 5. The U2N remote UE and gNB establish security following Uu procedures and forward security messages via the U2N relay UE.

[0324] 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.

[0325] 2) Radio link failure

[0326] 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.

[0327] The U2N relay UE declares a Radio Link Failure (RLF) following the same criteria.

[0328] After declaring RLF, the U2N relay UE also takes the following actions on top of the actions:

[0329] - 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.

[0330] After detecting PC5 RLF, the U2N remote UE can trigger connection re-establishment.

[0331] 3)RRC connection reestablishment

[0332] The U2N remote UE may perform the following actions during the RRC connection reestablishment procedure:

[0333] - If only a suitable cell is available, the U2N remote UE initiates the RRC re-establishment procedure towards the suitable cell;

[0334] - 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;

[0335] - 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.

[0336] 4)RRC connection recovery

[0337] The RRC connection recovery mechanism is applied to the U2N remote UE.

[0338] 5) System Information

[0339] 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.

[0340] 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.

[0341] 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.

[0342] 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.

[0343] 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.

[0344] 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.

[0345] 6) Paging

[0346] 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.

[0347] 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:

[0348] - 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.

[0349] -Delivery of paging for 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).

[0350] 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.

[0351] 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.

[0352] The U2N relay UE may use unicast signaling to send paging to the U2N remote UE via PC5.

[0353] 7) Access Control

[0354] 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.

[0355] 8) Mobility registration update and RAN area update

[0356] 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.

[0357] Service continuity for L2 U2N trunking

[0358] 1) Switching from indirect to direct path

[0359] Fig.14 The process of U2N remote UE handover to direct Uu cell is illustrated.

[0360] For service continuity over L2 U2N relay, in case the U2N remote UE switches to direct path, the following procedure is used:

[0361] 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.

[0362] 2. The gNB decides to switch the U2N remote UE to the direct Uu path.

[0363] 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.

[0364] 4. The U2N remote UE synchronizes with the gNB and performs random access.

[0365] 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.

[0366] 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).

[0367] 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.

[0368] 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.

[0369] Note: Step 8 can be performed at any time after Step 4. Step 8 is independent of Step 6 and Step 7.

[0370] 2) Switching from direct to indirect paths

[0371] Fig.15 The process of U2N remote UE switching to indirect path is illustrated.

[0372] 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.

[0373] 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:

[0374] 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.

[0375] - 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.

[0376] - 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.

[0377] 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.

[0378] 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.

[0379] 4. The U2N remote UE establishes a PC5 connection with the target U2N relay UE.

[0380] 5. The U2N remote UE completes the path switching process by sending an RRCReconfigurationComplete message to the gNB via the relay UE.

[0381] 6. The data path is switched from the direct path to the indirect path between the U2N remote UE and the gNB.

[0382] 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.

[0383] Sidelink Discovery

[0384] The UE may perform NR sidelink discovery when in-coverage or out-of-coverage for non-relay operation.

[0385] The relay discovery mechanism (in addition to the discovery message transmission based on U2N relay-specific thresholds) is also applied to sidelink discovery.

[0386] Multipath Operation

[0387] Fig.16 is a diagram for explaining a method of establishing a U2N bearer for an L2 U2N remote UE and an L2 U2N relay UE.

[0388] A method for forming, by a remote UE, a multipath including a direct path and an indirect path and performing data transmission / reception based on the multipath includes the following steps:

[0389] 1. The U2N remote UE and the U2N relay UE perform a discovery procedure and establish a PC5-RRC connection using the NR V2X procedure (S161).

[0390] 2. After PC5-RRC connection establishment is performed using PC5 unicast link establishment, the remote UE and the relay UE may exchange their own UE capabilities by triggering the sidelink UE capability transfer procedure, wherein the remote UE sends a UECapabilityEnquirySidelink message requesting the MP capabilities of the relay UE to the relay UE, and then the relay UE sends a UECapabilityInformationSidelink message including its MP capabilities to the remote UE. Afterwards, the relay UE may send a UECapabilityEnquirySidelink message requesting the MP capabilities of the remote UE to the remote UE, and then the remote UE sends a UECapabilityInformationSidelink message including its MP capabilities to the relay UE.

[0391] The MP capabilities of the UE may include one or more of the following:

[0392] -Whether the UE supports multipath operation as a remote UE and / or as a relay UE

[0393] -SL / UL / DL frequency carriers / bands where the UE may support MP operation for transmission and / or reception

[0394] - Combination of SL carrier / band and UL carrier / band where the UE can support MP operation for transmissions from the UE

[0395] - A combination of SL carrier / band and DL carrier / band where the UE can support MP operation for reception at the UE.

[0396] If the relay UE recognizes that both the relay UE and the remote UE support MP capabilities based on the above-mentioned exchange of sidelink UE capabilities, and the remote UE is in RRC_CONNECTED, the relay UE that is not in RRC_CONNECTED may initiate an RRC connection establishment procedure.

[0397] 3. If the U2N remote UE does not have a direct Uu RRC connection, the U2N remote UE sends its first RRC message (i.e., RRCSetupRequest) for connection establishment with the gNB via the relay UE using the designated PC5 relay RLC channel configuration. If the U2N relay UE is not in RRC_CONNECTED, it needs to perform its own connection establishment upon receiving a message on the designated PC5 relay RLC channel. During the RRC connection establishment process of the relay UE, the gNB may configure the SRB0 of the relay Uu relay RLC channel to the U2N relay UE. The gNB responds to the U2N remote UE with an RRCSetup message. The RRCSetup message is sent to the U2N remote UE using the SRB0 of the designated PC5 relay RLC channel on the relay Uu (S163).

[0398] 4. The gNB and the U2N relay UE perform a relay channel establishment procedure on Uu. According to the configuration from the gNB, the U2N relay / remote UE establishes a PC5 relay RLC channel to relay SRB1 to the U2N remote / relay UE via PC5 (S164).

[0399] 5. The U2N remote UE uses the SRB1 of the channel on the relay PC5 and the SRB1 of the channel configured for the U2N relay UE on the relay Uu to send an RRCSetupComplete message to the gNB via the U2N relay UE. Then, the U2N remote UE performs an RRC connection through Uu (S165).

[0400] 6. The U2N remote UE and gNB establish security after the Uu procedure, and the security message is forwarded through the U2N relay UE (S166).

[0401] 7. The U2N remote UE informs the gNB of the UE capabilities of the remote UE, including, for example, whether the remote UE supports U2N bearers / channels and / or MP operations.

[0402] 8. The U2N relay UE informs the gNB of the UE capabilities of the relay UE, including, for example, whether the relay UE supports U2N bearers / channels and / or MP operations.

[0403] 9. The gNB indirectly sends an RRCReconfiguration message to the U2N remote UE via the U2N relay UE to set up SRB2 / DRB and / or configure SL DRX for relay purposes (S162). The U2N remote UE sends an RRCReconfigurationComplete message to the gNB via the U2N relay UE 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.

[0404] 10. 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.

[0405] 11. The relay UE may also indicate one or more of the following to the remote UE via the sidelink message:

[0406] -The cell identity of the PCell used to relay the UE.

[0407] - The PLMN identity of the registered PLMN used to relay the UE.

[0408] - Tracking area code of the tracking area where the relay UE is registered for the PCell

[0409] A. If the relay UE and the remote UE are configured with different serving cells, different tracking areas and / or different PLMNs, the remote UE and / or the relay UE informs the gNB of one or more of the different serving cells, different tracking areas and / or different PLMNs, for example, via a SidelinkUEInformationNR message.

[0410] B. The sidelink message may be a RemoteUEInformationSidelink message, a UEAssistanceInformationSidelink message, a RRCReconfigurationSidelink message, or a RRCReconfigurationCompleteSidelink message.

[0411] 12. The remote UE may receive system information from the relay UE. Based on the received system information, the remote UE may identify whether the serving cell of the relay UE can support sidelink resources for sidelink transmission / reception and / or MP operation (e.g., based on resource pool configuration in the system information or dedicated signaling).

[0412] If the remote UE and the relay UE can support MP operation on the DL / UL carrier of the serving cell and the SL carrier in which the sidelink transmission and / or sidelink reception between the remote UE and the relay UE has been performed, or the serving cell supports sidelink resources for sidelink transmission / reception and / or MP operation (e.g., based on dedicated signaling or resource pool configuration in system information), the remote UE may perform one or more of the following steps:

[0413] -If the serving cell of the relay UE indicated by the received system information is different from the serving cell camped on by the remote UE, the remote UE may reselect to the indicated cell based on the cell reselection process, or the remote UE suspends the multipath operation with the relay UE. If the remote UE cannot reselect to the indicated cell based on the cell reselection process, the remote UE suspends the multipath operation with the relay UE.

[0414] -If the tracking area of ​​the relay UE indicated by the received system information 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 system information, or the remote UE terminates 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 terminates the multipath operation with the relay UE.

[0415] -If the PLMN of the relay UE indicated by the received system information 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 terminates 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 terminates the multipath operation with the relay UE.

[0416] A. The relay UE may inform the remote UE of the serving cell, tracking area and / or PLMN of the relay UE by sending a PC5-RRC message such as a RemoteUEInformationSidelink message or a UEAssistanceInformationSidelink message or an RRCReconfigurationSidelink message or an RRCReconfigurationCompleteSidelink message.

[0417] 13. 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.

[0418] 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:

[0419] A. If the measObject is associated with an L2 U2N relay UE, the remote UE performs corresponding measurements associated with the candidate relay UE on the frequencies indicated in the measObject involved (as described in 5.5.3.4 of TS38.331). When performing measurements, the UE filters the measurement results based on layer 3 filtering (as described in 5.5.3.2 of TS38.331) before evaluating the reporting criteria or measurement reporting for each candidate L2 U2N relay UE measurement quantity (as described in 5.5.3.4 of TS38.331):

[0420] B. For each L2 U2N relay UE measurement quantity to be derived, the remote UE shall:

[0421] - 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

[0422] - Application layer 3 filtering (as described in 5.5.3.2 of TS 38.331).

[0423] C. If the corresponding measObject involves L2 U2N relay UE:

[0424] - if the event Y1-Relay is configured in the corresponding reportConfig; or

[0425] - If the corresponding reportConfig includes a reportType set to periodic:

[0426] The remote UE shall consider any L2 U2N relay UE detected on the associated frequency as applicable to this measId;

[0427] ReportType (or event type) may be determined or set based on Tables 6 to 10 below.

[0428] [Table 6]

[0429]

[0430]

[0431] [Table 7]

[0432]

[0433]

[0434] [Table 8]

[0435]

[0436] [Table 9]

[0437]

[0438]

[0439]

[0440] [Table 10]

[0441]

[0442]

[0443] 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:

[0444] - Include the measurement report entry for the measId in VarMeasReportList;

[0445] - Set numberOfReportsSent defined for this measId in VarMeasReportList to 0;

[0446] - Include the L2 U2N relay UE involved in the relaysTriggeredList defined for the measId in VarMeasReportList;

[0447] - Initiate the measurement reporting procedure, as in the next step.

[0448] 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:

[0449] - Set numberOfReportsSent defined for this measId in VarMeasReportList to 0;

[0450] - Include the L2 U2N relay UE involved in the relaysTriggeredList defined for the measId in VarMeasReportList;

[0451] - Initiate the measurement reporting procedure, as in the next step.

[0452] 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:

[0453] - Remove the L2 U2N relay UE involved from the relaysTriggeredList defined for the measId in VarMeasReportList;

[0454] - If reportOnLeave is set to true for the corresponding reporting configuration, the measurement reporting procedure is initiated, as in the next step.

[0455] - if the relaysTriggeredList defined for the measId in VarMeasReportList is empty, remove the measurement report entry for the measId in VarMeasReportList; and / or stop the periodic report timer for the measId if it is running;

[0456] F. If reportType is set to periodic, and if the (first) measurement result is available:

[0457] - if reportAmount exceeds 1: the UE shall initiate the measurement reporting procedure (as specified in 5.5.5 of TS 38.331) immediately after the amount to be reported becomes available to the NR SpCell or serving L2U2N relay UE (if the UE is a L2U2N remote UE);

[0458] - 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 of TS 38.331); 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);

[0459] 14. After initiating the measurement report procedure in the previous step, for the measId that triggered the measurement report 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.

[0460] 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;

[0461] - 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.

[0462] B. If there is at least one applicable neighboring cell to report (see Table 11):

[0463] a. 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 the following:

[0464] - 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;

[0465] - 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;

[0466] b. 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.

[0467] - if the measObject associated with this measId relates to a 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 concerned, including the best L2 U2N relay UE first;

[0468] -For candidate L2 U2N relay UEs, the UE shall consider yN-Threshold2-Relay as the ranking quantity;

[0469] - For a candidate L2 U2N relay UE, the UE shall consider reportQuantityRelay as the ranking quantity;

[0470] [Table 11]

[0471]

[0472] C. In the RRCReconfiguration message, the gNB may configure the reportConfig associated with measId and eventID as follows, with the measId that triggered the measurement report set to eventTriggered, and eventID set to one or more events for the event-triggered measurement report:

[0473] >For a serving cell camped by a remote UE, for a serving cell camped by a relay UE, or for a best-ranked suitable cell for a remote UE, the remote UE may be configured using one or more of the following events:

[0474] - Event A1 (Service / best cell quality becomes better than threshold)

[0475] - Event A2 (Service / best cell quality becomes worse than threshold)

[0476] - Event A3 (neighbor cell becomes better than serving / best cell in terms of cell quality)

[0477] - Event N1 (neighbor cell quality becomes better than the threshold)

[0478] The remote UE can trigger this event only for cells indicated by the gNB in ​​the RRCReconfiguration message.

[0479] - Event N2 (neighbor cell quality becomes worse than the threshold)

[0480] The remote UE can trigger this event only for cells indicated by the gNB in ​​the RRCReconfiguration message.

[0481] Note that the best ranked suitable cell for the remote UE or the serving cell on which the remote UE is camping may be the same as or different from the serving cell for the relay UE.

[0482] 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.

[0483] >For a serving cell on which the remote UE is camped or a serving frequency of a best-ranked suitable cell for the remote UE, for a frequency with a highest cell reselection priority or a cell reselection priority higher than a priority threshold (e.g., a priority higher than a threshold), or for a non-serving frequency for the remote UE, the remote UE may be configured using one or more of the following events:

[0484] - Event S1 (suitable / best cell quality on this frequency becomes better than a threshold)

[0485] - Event S2 (the quality of the suitable / best cell on this frequency becomes worse than the threshold)

[0486] - Event S3 (neighbor suitable cell becomes better than best cell in terms of cell quality)

[0487] Note that if the above events are triggered for a suitable / best cell or a neighbor cell, the remote UE reports the following information to the gNB.

[0488] Measurement results on suitable / best cell and / or neighbor suitable cells

[0489] As a result of the suitability check based on reading the SIB1 of the neighbor cell, whether the neighbor cell is suitable.

[0490] Global cell identity of suitable / best cell

[0491] Global cell identifier of the neighboring cell

[0492] D. In the RRCReconfiguration message, the gNB may configure the reportConfig associated with the measId as reportType. The measId that triggers the measurement report is set to periodic, so the remote UE performs the following operations:

[0493] >For the frequencies indicated by the gNB, 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 named (suitable) cell.

[0494] >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.

[0495] >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.

[0496] -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 includes measurement results about each other cell in cellsToAddModList in descending order of the sorting amount (for example, in descending order of the measured RSRP or RSRQ results).

[0497] 15. If the remote UE and the relay UE can support MP operation on the DL / UL carrier of the serving cell and the SL carrier in which sidelink transmission and / or sidelink reception between the remote UE and the relay UE has been performed, or the serving cell supports sidelink resources for sidelink transmission / reception and / or MP operation (e.g., based on dedicated signaling or resource pool configuration in system information), the remote UE may initiate random access or RRC connection (re)establishment as follows:

[0498] A. If the entry conditions of one or more of the above events in the previous steps are met for the cell and one or more of the above events are triggered for the cell, the remote UE having an indirect path with the gNB via the relay UE may perform one or more of the following to establish a direct path with the gNB:

[0499] >The remote UE initiates a random access procedure to the cell of the relay / remote UE or the serving cell. In the random access, the remote UE sends MSG1 or MSGA.

[0500] -MSG3 or MSGA PUSCH in the random access procedure includes a C-RNTI MAC CE indicating the C-RNTI (or other UE ID) of the remote UE, where the C-RNTI has been allocated by the gNB via the relay UE.

[0501] - For MSG1 or MSGA, a dedicated RACH preamble may be allocated by the gNB via the relay UE. If no dedicated RACH preamble is allocated, the relay UE may forward SIB1 to the remote UE to provide the RACH configuration for this random access, or the remote UE may receive SIB1 directly from the cell

[0502] >The remote UE initiates the RRC connection (re)establishment procedure to the relay / remote UE's cell or serving cell.

[0503] >The remote UE notifies the gNB of information about the cell, measurement results about the cell and / or events triggered for the cell, for example by sending a SidelinkUEInformationNR message or a measurement report indirectly via a relay UE or directly after random access or RRC connection (re)establishment is completed.

[0504] >The remote UE notifies the relay UE of information about the cell, measurement results about the cell, and / or events triggered for the cell, for example, by sending a PC5-RRC message. Upon receiving the PC5-RRC message, the relay UE notifies the gNB of information about the cell, measurement results about the cell, and / or events triggered for the cell with the source or destination identity of the remote UE.

[0505] Alternatively, the gNB may trigger a random access procedure and / or an RRC connection (re)establishment procedure from a remote UE having an indirect path with the gNB via a relay UE, so that the remote UE sets up a direct path with the gNB, as described in the next steps.

[0506] 16. If the remote UE having an indirect path with the gNB via the relay UE does not have a direct path with the gNB, the gNB may trigger a random access procedure and / or an RRC connection (re)establishment procedure to enable the remote UE to set up a direct path with the gNB as follows:

[0507] A.Alt A: The gNB triggers the paging procedure for the remote UE.

[0508] >The gNB constructs a paging message and sends the paging message to the remote UE indirectly via the relay UE and / or directly on the serving cell of the relay / remote UE.

[0509] >The remote UE receives the paging message indirectly via the relay UE or directly by monitoring the remote UE's paging occasion from the relay / remote UE's serving cell.

[0510] - The paging message may include one or more of the following:

[0511] It can be the UE ID of the remote UE's s-TMSI, C-RNTI or source / destination ID.

[0512] The cell ID of the cell.

[0513] RACH configuration at the cell

[0514] Indication for triggering RACH

[0515] Dedicated RACH preamble

[0516] Indication for multipath or direct path

[0517] -If the remote UE is able to directly monitor the paging occasion, the remote UE can determine the PO of the remote UE based on the C-RNTI allocated by the gNB via the relay UE.

[0518] - Based on the RACH configuration provided by the paging message, the paging message triggering the RACH may trigger a random access procedure and / or an RRC connection (re)establishment to the indicated cell.

[0519] If there is no cell indicated in the paging message, then as a result of the cell reselection process, the remote UE triggers a random access procedure and / or RRC connection (re)establishment at the serving cell of the relay UE or the serving cell of the remote UE or the best ranked suitable cell of the remote UE.

[0520] If there is no RACH configuration in the paging message, the remote UE triggers a random access procedure and / or RRC connection (re)establishment based on the RACH configuration in the system information.

[0521] If a dedicated RACH preamble is included in the paging message, the remote UE triggers a random access procedure and / or RRC connection (re)establishment using the dedicated RACH preamble. Otherwise, the remote UE performs contention-based RACH.

[0522] If multipath is indicated, the remote UE triggers a random access procedure and / or an RRC connection (re)establishment while maintaining the indirect path with the relay UE.

[0523] If a single path is indicated, the remote UE triggers a random access procedure and / or RRC connection (re)establishment after releasing the indirect path and / or PC5-RRC connection with the relay UE, or the remote UE releases the indirect path and / or PC5-RRC connection with the relay UE after the random access procedure and / or RRC connection (re)establishment.

[0524] B. Alt B: The relay UE triggers RACH and / or RRC connection (re)establishment from the remote UE.

[0525] >The relay UE may trigger a RACH and / or RRC connection (re)establishment from the remote UE if one or more of the following conditions are met.

[0526] -When an RRCReconfiguration message for configuration of multipath operation is received from the gNB.

[0527] The relay UE may inform the gNB that the remote UE is not in RRC_CONNECTED.

[0528] If the remote UE is not in RRC_CONNECTED, the gNB may request the relay UE to initiate an RRC connection (re)establishment, e.g. via the remote UE.

[0529] -When receiving system information from the gNB for configuration of multipath operation

[0530] - When one or more of the following conditions configured by the gNB for multipath operation are met

[0531] The DL data rate, UL data rate, or SL data rate on one or more or all relayed bearers for the remote UE becomes higher than a threshold indicated by the gNB or the remote UE or determined by the relay UE.

[0532] The amount of DL data, the amount of UL data, or the amount of SL data in the buffer of one or more or all relayed bearers in the relay UE becomes higher than a threshold indicated by the gNB or the remote UE or determined by the relay UE.

[0533] The QoS requirements (eg, delay requirements or error rates) of one or more or all relayed bearers for the remote UE cannot be met for a certain duration.

[0534] - If the gNB is configured via system information or UE-specific signaling to allow multipath operation for a relay UE or a remote UE or a pair of a relay UE and a remote UE.

[0535] >The relay UE may trigger a RACH and / or RRC connection (re)establishment from the remote UE by one of the following:

[0536] - Codepoints of specific fields in the Sidelink Control Information (SCI)

[0537] SCI is one of the first-level SCI and the second-level SCI.

[0538] The SCI indicates the destination identity of the remote UE.

[0539] - The value of a specific field in the sidelink MAC control element

[0540] -The value of a specific parameter in the PC5-RRC message.

[0541] >If the RRCReconfiguration message from the gNB indicates triggering of RACH and / or RRC connection (re)establishment from the remote UE, the relay UE indicates triggering of RACH and / or RRC connection (re)establishment from the remote UE and then sends an RRCReconfigurationComplete message to the gNB.

[0542] - If the relay UE fails to indicate triggering of RACH and / or RRC connection (re)establishment from the remote UE, e.g. due to sidelink failure or consecutive NACKs to this indication, the relay UE sends an RRCReconfigurationComplete message indicating "Sidelink Failure" to the gNB, or the relay UE initiates the RRC re-establishment procedure.

[0543] C. Alt C: The remote UE triggers RACH and / or RRC connection (re)establishment based on whether a certain condition is met.

[0544] >The remote UE may trigger a RACH and / or RRC connection (re)establishment if one or more of the following conditions are met.

[0545] a. When an RRCReconfiguration message for configuration of multipath operation is received from the gNB.

[0546] b. When receiving system information for configuration of multipath operation from gNB

[0547] c. When one or more of the following conditions configured by the gNB for multipath operation are met

[0548] -The SL RX or SL TX data rate on one or more or all relayed bearers from / to the relay UE becomes higher than a threshold indicated by the gNB or relay UE or determined by the remote UE.

[0549] -The amount of SLRX or SLTX data in the buffer of one or more or all relayed bearers in the remote UE for the relay UE becomes higher than a threshold indicated by the gNB or the relay UE or determined by the remote UE.

[0550] - The QoS requirements (eg delay requirements or error rates) of one or more or all relayed bearers from / to the relay UE cannot be met for a certain duration.

[0551] d. If the gNB configures the allowed multi-path operation for the relay UE or the remote UE or a pair of the relay UE and the remote UE through system information or UE-specific signaling received via the relay UE.

[0552] Upon the above trigger, the remote UE initiates a random access procedure to the cell indicated by the gNB (or relay UE) or the serving cell of the relay / remote UE. Alternatively, the remote UE performs cell reselection to the cell based on the cell reselection process and then initiates a random access procedure to the cell.

[0553] >In random access, the remote UE sends MSG1 or MSGA.

[0554] -MSG3 or MSGA PUSCH in the random access procedure includes a C-RNTI MAC CE indicating the C-RNTI (or other UE ID) of the remote UE, where the C-RNTI has been allocated by the gNB via the relay UE.

[0555] -For MSG1 or MSGA, a dedicated RACH preamble may be allocated by the gNB via the relay UE. If no dedicated RACH preamble is allocated, the relay UE may forward SIB1 to the remote UE to provide the RACH configuration for this random access, or the remote UE may receive SIB1 directly from the cell.

[0556] > Using random access, the remote UE can initiate the RRC connection (re)establishment procedure to the cell of the relay / remote UE or the serving cell.

[0557] >If there is no indicated cell, then as a result of the cell reselection process, the remote UE triggers a random access procedure and / or RRC connection (re)establishment at the serving cell of the relay UE or the serving cell of the remote UE or the best ranked suitable cell of the remote UE.

[0558] >If there is no RACH configuration provided by dedicated signaling from the gNB, the remote UE triggers a random access procedure and / or RRC connection (re)establishment based on the RACH configuration in the system information.

[0559] > If a dedicated RACH preamble is provided by dedicated signaling from the gNB, the remote UE triggers a random access procedure and / or RRC connection (re)establishment using the dedicated RACH preamble. Otherwise, the remote UE performs contention-based RACH.

[0560] >If the gNB indicates or allows multipath based on system information or UE-specific signaling, the remote UE triggers a random access procedure and / or RRC connection (re)establishment while maintaining an indirect path with the relay UE.

[0561] >If the gNB indicates a single path or the gNB does not allow multipath based on system information or UE-specific signaling, the remote UE triggers a random access procedure and / or RRC connection (re)establishment after releasing the indirect path and / or PC5-RRC connection with the relay UE, or the remote UE releases the indirect path and / or PC5-RRC connection with the relay UE after the random access procedure and / or RRC connection (re)establishment.

[0562] >The remote UE notifies the gNB of information about the cell, measurement results about the cell and / or events triggered for the cell, for example by sending a SidelinkUEInformationNR message or a measurement report indirectly via a relay UE or directly after random access or RRC connection (re)establishment is completed.

[0563] 17. After the RRC connection is established and the PC5-RRC connection is established, the relay UE and / or the remote UE may perform the sidelink UE information for the NR sidelink communication process. During the NR sidelink communication process, the UE (or the relay UE) sends a SidelinkUEInformationNR message to the gNB (S167).

[0564] The UE shall set the content of the SidelinkUEInformationNR message as follows:

[0565] 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:

[0566] - The UE shall include sl-RxInterestedFreqListDisc and set it to the frequency for NR side link discovery announcement reception;

[0567] - 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.

[0568] 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:

[0569] - sl-DestinationIdentityDisc is set to the destination identity configured by upper layers for NR sidelink discovery announcement transmission;

[0570] - 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;

[0571] - sl-CastTypeDisc is set to the cast type of the associated destination identifier configured by upper layers for NR sidelink discovery announcement transmission;

[0572] - set sl-InterestedFreqListDisc to indicate the frequency of the associated destination for NR sidelink discovery advertisement transmission;

[0573] - Set sl-TypeTxSyncListDisc to the current synchronization reference type used on the associated sl-InterestedFreqList for NR sidelink discovery announcement transmission;

[0574] - sl-DiscoveryType is set to the current discovery type of the associated destination identifier configured by upper layers for NR sidelink discovery announcement transmission;

[0575] 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:

[0576] - 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:

[0577] - sl-DestinationIdentityL2U2N is set to the destination identity configured by upper layers for NR sidelink L2 U2N relay communication transmission;

[0578] - set sl-TxInterestedFreqListL2U2N to indicate the frequencies of the associated destinations for NR sidelink L2 U2N relay communication transmissions;

[0579] - Set sl-TypeTxSyncListL2U2N to the current synchronization reference type used on the associated sl-InterestedFreqListL2U2N for NR sidelink L2 U2N relay communication transmissions;

[0580] - Set sl-LocalID-Request to the local ID of the requesting L2 U2N remote UE;

[0581] - Set sl-PagingIdentity-RemoteUE to the paging UE ID received from the peer L2 U2N remote UE;

[0582] - sl-CapabilityInformationSidelink is set to include the UECapabilityInformationSidelink message received from the peer UE, if any.

[0583] - Include ue-Type and set it to relayUE;

[0584] - Includes an indication of support / request for multipathing

[0585] - Includes an indication of the RRC state of the remote UE or whether the remote UE is in RRC_CONNECTED.

[0586] - Includes the cell identity of the PCell of the remote UE.

[0587] - Includes the PLMN identity of the remote UE's registered PLMN.

[0588] - The tracking area code including the tracking area where the remote UE is registered for the PCell.

[0589] 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:

[0590] - 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:

[0591] - set sl-TxInterestedFreqListL2U2N to indicate the frequencies of the associated destinations for NR sidelink L2 U2N relay communication transmissions;

[0592] - Set sl-TypeTxSyncListL2U2N to the current synchronization reference type used on the associated sl-InterestedFreqListL2U2N for NR sidelink L2 U2N relay communication transmissions;

[0593] - sl-CapabilityInformationSidelink is set to include the UECapabilityInformationSidelink message received from the peer UE, if any.

[0594] - include ue-Type and set it to remoteUE;

[0595] - Includes an indication of support / request for multipathing

[0596] - Includes an indication of the RRC state of the relay UE or whether the relay UE is in RRC_CONNECTED.

[0597] - Includes the cell identity of the PCell of the relay UE.

[0598] - Includes the PLMN identity of the relay UE's registered PLMN.

[0599] - Includes the tracking area code of the tracking area where the relay UE is registered for the PCell.

[0600] E. If configured by upper layers to send NR sidelink L3 U2N relay communications, the relay UE or remote UE shall:

[0601] - 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:

[0602] - sl-DestinationIdentity is set to the destination identity configured by upper layers for NR sidelink L3 U2N relay communication transmission;

[0603] - 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;

[0604] - 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;

[0605] - 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;

[0606] - set sl-TxInterestedFreqList to indicate the frequencies of the associated destinations for NR sidelink L3 U2N relay communication transmissions;

[0607] - Set sl-TypeTxSyncList to the current synchronization reference type used on the associated sl-InterestedFreqList for NR sidelink L3 U2N relay communication transmissions.

[0608] - sl-CapabilityInformationSidelink is set to include the UECapabilityInformationSidelink message received from the peer UE, if any.

[0609] - 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;

[0610] - Includes indication of multipath support / request

[0611] - Includes an indication of the RRC state of the relay UE or whether the relay UE is in RRC_CONNECTED.

[0612] - Includes an indication of the RRC state of the remote UE or whether the remote UE is in RRC_CONNECTED.

[0613] - If the UE acts as an NR sidelink U2N remote UE:

[0614] Includes the cell identifier of the PCell of the relay UE.

[0615] Includes the PLMN identifier of the registered PLMN of the relay UE.

[0616] Includes the tracking area code of the tracking area where the relay UE is registered for the PCell.

[0617] - If the UE acts as an NR sidelink U2N relay UE:

[0618] Includes the cell identity of the PCell of the remote UE.

[0619] Includes the PLMN identity of the remote UE's registered PLMN.

[0620] Contains the tracking area code of the tracking area where the remote UE is registered for the PCell.

[0621] 18. Upon receiving a report from the remote UE and / or the relay UE (e.g., a MeasurementReport message and / or a SidelinkUEInformationNR message from the remote UE and / or a SidelinkUEInformationNR message from the relay UE and / or the multipath configuration described in the following steps), the gNB determines whether to add a direct path with the gNB for the remote UE.

[0622] 19. 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 perform a handover of the relay UE and / or the remote UE to move the relay UE and / or the remote UE to the same cell, the same tracking area and / or the same PLMN.

[0623] 20. If both the relay UE and the remote UE are in RRC_CONNECTED, and if the gNB determines whether to add a direct path for the remote UE according to the previous step, the gNB configures the direct path for the remote UE, for example, by sending an RRCReconfiguration message to the relay UE and the remote UE, respectively (S168). The gNB may send the RRCReconfiguration message directly to the remote UE after random access and / or RRC connection (re)establishment, or the gNB may send the RRCReconfiguration message to the remote UE indirectly via the relay UE.

[0624] - If the RRCReconfiguration message includes sl-L2RelayUEConfig, the relay UE performs the L2 U2N relay UE configuration procedure to (re)configure or release zero, one or more indirect bearers and release zero, one or more split bearers.

[0625] - If the RRCReconfiguration message includes sl-L2RemoteUEConfig, the remote UE performs the L2 U2N Remote UE Configuration procedure to (re)configure zero, one or more direct bearers and zero, one or more split bearers.

[0626] - If the RRCReconfiguration message 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.

[0627] - Indirect bearer or split bearer involves the establishment of a Uu relay RLC channel.

[0628] - Indirect bearer is configured with an indirect link consisting of a Uu link and a side link.

[0629] - Direct bearer is configured with a direct link on Uu only.

[0630] - The split bearer is configured with both an indirect path and a direct path of the split bearer. The gNB may select one or both of the indirect path and the direct path for downlink data transmission to the remote UE, and the remote UE may select one or both of the indirect path and the direct path for uplink data transmission to the gNB.

[0631] A. Option 1: Joint RRC Reconfiguration

[0632] a. 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 configurations regarding modification or release of an indirect / split bearer applied to the relay UE, and the second part includes configurations regarding modification or release of an indirect / split bearer applied to the remote UE and addition of a direct bearer or a direct path of a split bearer.

[0633] >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.

[0634] -For example, the second part is included in an RRC container of an 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. Upon 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 a PDCP layer, an SRAP layer, and an 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.

[0635] -Upon 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 sends it 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 sends it 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 reestablishment 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.

[0636] In case of RRC reestablishment procedure on Uu interface, the remote UE performs random access to the gNB and as a result of the procedure, only direct bearers are configured. In the RRC reestablishment procedure, the relay UE sends an RRCReestablishmentComplete message indicating failure of U2N configuration or multipath configuration along with the source or destination identity of the relay UE and / or remote UE.

[0637] 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 or destination identity of the relay UE and / or remote UE.

[0638] -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.

[0639] -When the PC5-RRC connection is released or when a sidelink relay reconfiguration failure or a multipath configuration failure is received, 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, when the PC5-RRC connection is released, when a sidelink relay reconfiguration failure or a multipath configuration failure is received or detected, 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. During the RRC reestablishment procedure, the relay UE performs random access to the gNB, and as a result of the procedure, only the direct bearer is configured. In the RRC re-establishment process, the relay UE sends an RRCReestablishmentComplete message indicating the failure of the U2N configuration or the multi-path configuration and the source or destination identity of the relay UE and / or the remote UE.

[0640] >Option 1B: The relay UE forwards the second part to the remote UE by sending a PC5 RRC message (e.g., an RRCReconfigurationSidelink message or a UuMessageTransferSidelink message) to the remote UE.

[0641] -For example, the second part is included in an RRC container of an RRCReconfiguration message or a UuMessageTransferSidelink 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 the first security key (or a second security key configured between the gNB and the remote UE). Upon 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 a 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 an RRCReconfigurationSidelink message sent to the remote UE. The second part may be included in the RRC container of the RRCReconfigurationSidelink message, or the second part is reconstructed to be included in the RRCReconfigurationSidelink message.

[0642] -When 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 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.

[0643] In case of RRC reestablishment procedure on Uu interface, the remote UE performs random access to the gNB and as a result of the procedure, only direct bearers are configured. In the RRC reestablishment procedure, the relay UE sends an RRCReestablishmentComplete message indicating failure of U2N configuration or multipath configuration along with the source or destination identity of the relay UE and / or remote UE.

[0644] 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 or destination identity of the relay UE and / or remote UE.

[0645] -Upon receiving the RRCReconfigurationFailureSidelink message, upon receiving the sidelink relay reconfiguration failure or the multipath configuration failure, upon detecting the sidelink failure (e.g., due to the expiration of the timer T400), or if the relay UE fails to apply the first part of the configuration, the relay UE sends the gNB an RRCReconfigurationFailure or RRCReconfigurationComplete message failure of the U2N configuration or the multipath configuration. Alternatively, upon receiving the RRCReconfigurationFailureSidelink message, upon receiving the sidelink relay reconfiguration failure or the multipath configuration failure, upon detecting the sidelink failure (e.g., due to the expiration of the timer T400), or if the relay UE fails to 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. During the RRC re-establishment procedure, the relay UE performs random access to the gNB and as a result of the procedure, only direct bearers are configured. During the RRC re-establishment procedure, the relay UE sends an RRCReestablishmentComplete message indicating the failure of U2N configuration or multipath configuration and the source or destination identity of the relay UE and / or remote UE.

[0646] >In Option 1, when the remote UE or relay UE performs the RRC reestablishment procedure, it may also inform the gNB which UE failed to apply the U2N configuration or multipath configuration, i.e., the remote UE or relay UE.

[0647] B. Option 2: Separate delivery of RRC reconfiguration

[0648] a. The gNB sends a first RRCReconfiguration message to the relay UE. The first RRCReconfiguration message includes a configuration regarding modification or release of at least an indirect / split bearer applied to the relay UE.

[0649] >When 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, the relay UE initiates an RRC reestablishment procedure when the PC5-RRC connection is released, or when a sidelink relay reconfiguration failure or a multipath configuration failure is received or detected, 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. During the RRC reestablishment procedure, the relay UE performs random access to the gNB, and as a result of the procedure, only direct bearers are configured. During the RRC reestablishment procedure, the relay UE sends an RRCReestablishmentComplete message indicating a failure of U2N configuration or multipath configuration and a source or destination identity of the relay UE and / or the remote UE.

[0650] b. The gNB sends a second RRCReconfiguration message to the remote UE. The second RRCReconfiguration message includes configurations for modification or release of the indirect / split bearer applied to the remote UE and addition of direct bearers and direct paths for split bearers.

[0651] >The gNB may send a second RRCReconfiguration message directly to the remote UE over the Uu interface, for example by using SRB1.

[0652] - Upon 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.

[0653] The RRCReconfigurationComplete or RRCReconfigurationFailure message is sent directly to the gNB by using SRB1, or indirectly to the gNB via a relay UE by using SL-RLC1 for SRB1.

[0654] 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 a sidelink relay reconfiguration failure or a multipath configuration failure.

[0655] -Alternatively, if the remote UE does not successfully apply the configuration of the second message, the remote UE initiates an RRC reestablishment 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, and / or notify the relay UE of a sidelink relay reconfiguration failure or a multipath configuration failure.

[0656] In case of RRC reestablishment procedure on Uu interface, the remote UE performs random access to the gNB and as a result of the procedure, only direct bearers are configured. In the RRC reestablishment procedure, the relay UE sends an RRCReestablishmentComplete message indicating failure of U2N configuration or multipath configuration along with the source or destination identity of the relay UE and / or remote UE.

[0657] 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 or destination identity of the relay UE and / or remote UE.

[0658] -When the PC5-RRC connection is released or when a sidelink relay reconfiguration failure or multipath configuration failure is received, the relay UE fails to send an RRCReconfigurationFailure or RRCReconfigurationComplete message for U2N configuration or multipath configuration 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.

[0659] -Alternatively, upon PC5-RRC connection release, upon 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. During the RRC reestablishment procedure, the relay UE performs random access to the gNB, and as a result of the procedure, only direct bearers are configured. During the RRC reestablishment procedure, the relay UE sends an RRCReestablishmentComplete message indicating a failure of U2N configuration or multipath configuration and a source 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.

[0660] >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).

[0661] -Upon 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, the relay UE does not forward the second RRCReconfiguration message received from the gNB to the remote UE when the PC5-RRC connection is released, or when a sidelink relay reconfiguration failure or a multipath configuration failure is received or detected, 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. During the RRC reestablishment procedure, the relay UE performs random access to the gNB, and as a result of the procedure, only the direct bearer is configured. In the RRC re-establishment process, the relay UE sends an RRCReestablishmentComplete message indicating the failure of the U2N configuration or the multi-path configuration and the source or destination identity of the relay UE and / or the remote UE.

[0662] -If the relay UE notifies the remote UE of a sidelink relay reconfiguration failure or a multipath configuration failure, the remote UE initiates an RRC reestablishment 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.

[0663] In case of RRC reestablishment procedure on Uu interface, the remote UE performs random access to the gNB and as a result of the procedure, only direct bearers are configured. In the RRC reestablishment procedure, the relay UE sends an RRCReestablishmentComplete message indicating failure of U2N configuration or multipath configuration along with the source or destination identity of the relay UE and / or remote UE.

[0664] 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 or destination identity of the relay UE and / or remote UE.

[0665] In the above steps, the core network (CN) node (such as AMF or SMF) may provide multipath configuration for the gNB and UE as follows:

[0666] >Alternative 1: When the remote UE establishes an RRC connection with the gNB (e.g., 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 configuration. If UE capabilities and / or NAS configuration are received, the gNB determines whether to configure multipath operation as described above.

[0667] - 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.

[0668] >Alternative 2: 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.

[0669] - Upon receiving an 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.

[0670] - 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. As described above, 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 RRC configuration provided by the gNB.

[0671] >Alternative 3: 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.

[0672] - In addition, when the relay UE establishes an RRC connection with the gNB (e.g., 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.

[0673] The CN node (e.g., AMF or SMF) may inform the gNB of the multipath configuration, or the addition of a multipath configuration, e.g. in the QoS profile for the remote UE and / or relay UE. The QoS profile is sent from the CN node to the gNB.

[0674] - The multipath related information in the QoS profile may indicate whether multipathing can be configured for one of the following:

[0675] Each PDU session

[0676] Each QoS flow

[0677] Each remote UE

[0678] Each relay UE

[0679] Each frequency

[0680] Each community

[0681] Each RAT

[0682] Each PLMN

[0683] Each tracking area

[0684] Each gNB

[0685] 21. In the above steps, the relay UE and the remote UE may release one or more or all of the 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.

[0686] To release the indirect path of the split bearer of the indirect path for 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:

[0687] A. The receiving PDCP entity of the bearer in the remote UE may trigger the sending of a PDCP status report to the gNB as follows:

[0688] > Send PDCP status report from remote UE directly to gNB or indirectly via relay UE to gNB.

[0689] >Upon receipt of the PDCP Status Report, the transmitting PDCP entity for the bearer in the gNB triggers “Multi-Path Data Switching” to perform retransmission or transmission of the PDCP SDU on the direct path towards the remote UE as described below.

[0690] > Upon / before receiving the RRCReconfiguration message for the release of the bearer, the SL RLC entity in the remote UE or relay UE may perform one or more of the following:

[0691] -Opt 1 (or Opt 21-1a): 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.

[0692] -Opt 2 (or, Opt 21-2a): For the SLRLC 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.

[0693] -Opt 3 (or, Opt 21-3a): For the SLRLC 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 to be sent to the peer AM RLC entity in the relay UE.

[0694] > Upon 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.

[0695] B. The receiving PDCP entity of the bearer in the gNB may trigger a PDCP status report to the remote UE as follows:

[0696] > Send PDCP status report from gNB directly to remote UE or indirectly via relay UE.

[0697] >Upon receipt of the PDCP Status Report, the transmitting PDCP entity for the bearer in the remote UE triggers “Multi-Path Data Switching” to perform retransmission or transmission of the PDCP SDU on the direct path towards the gNB as described below.

[0698] > Upon / before receiving the RRCReconfiguration message for the release of the bearer, the SL RLC entity in the relay UE or remote UE may perform one or more of the following:

[0699] -Opt 1 (or Opt 21-1b): 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.

[0700] -Opt 2 (or Opt 21-2b): 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.

[0701] -Opt 3 (or Opt 21-3b): For the SL RLC entity of the PC5 RLC channel of the uplink indirect path of 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.

[0702] >Upon receipt of 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 a negative acknowledgement was received via the RLC STATUS report, as described below, until release of the bearer on Uu / PC5.

[0703] -When receiving the SL RLC SDU and / or the SL RLC SDU segment from the remote UE, the relay UE performs uplink retransmission of the UL RLC SDU or the UL RLC SDU segment corresponding to the SL RLC SDU and / or the SL RLC SDU segment until the release of the bearer.

[0704] >Afterwards, the relay UE and / or remote UE informs the gNB of the release of the bearer, for example by sending a UE information message to the gNB.

[0705] - Before / after reception of the UE INFORMATION message, the gNB releases the PDCP / RLC entity corresponding to the bearer and / or PC5-RRC connection.

[0706] -The relay UE and / or remote UE releases the Uu / PC5PDCP / RLC entity (or multiple entities) corresponding to the bearer and / or PC5-RRC connection before / after sending the UE information message or when sending the RRCReconfiguration message to release the bearer to the remote UE and / or relay UE.

[0707] C. Upon / 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.

[0708] If PDCP status reporting is triggered, the receiving PDCP entity shall:

[0709] > Compile the PDCP status report as follows:

[0710] - Set the FMC field to RX_DELIV;

[0711] -if RX_DELIV <RX_NEXT:

[0712] then, from the first missing PDCP SDU (excluding the PDCP SDU) until the last out-of-sequence PDCP SDU (rounded up to the next multiple of 8) (including the PDCP SDU), or until the resulting PDCP Control PDU size is equal to 9000 bytes (including the PDCP SDU), whichever comes first, a bitmap field with a bit length equal to the number of COUNT is allocated;

[0713] For all PDCP SDUs that have not been received and optionally PDCP SDUs for which decompression has failed, set to "0" in the Bitmap field;

[0714] For all PDCP SDUs that have been received, set to "1" in the Bitmap field;

[0715] - The PDCP status report is submitted to lower layers as the first PDCP PDU for transmission via the transmitting PDCP entity as specified in clause 5.2.1 of 3GPP TS 38.323 for the Uu interface and in clause 5.2.3 of 3GPP TS 38.323 for the PC5 interface.

[0716] For AM DRBs, upon receiving a PDCP status report in the downlink or in the sidelink, the transmitting PDCP entity shall:

[0717] - For each PDCP SDU (if any), consider the bit in the bitmap that is set to "1" or the associated COUNT value that is less than the value of the FMC field (such as successfully delivered), and discard the PDCP SDU (as specified in clause 5.3 of 3GPP TS 38.323).

[0718] When a multipath data switch is triggered for a bearer (e.g., from an indirect bearer to a direct bearer), the transmitting PDCP entity in the DL, UL or SL for the bearer shall:

[0719] >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 SN is performed starting from the first PDCP SDU for which the successful delivery of the corresponding PDCP data PDU has not been acknowledged by the RLC entity associated with the indirect path, in ascending order of the COUNT value associated with the PDCP SDUs, as specified below:

[0720] - Perform header compression of PDCP SDU using ROHC.

[0721] - perform integrity protection and ciphering of the PDCP SDU using the COUNT value associated with this PDCP SDU;

[0722] - Submit the resulting PDCP data PDUs to the corresponding RLC entity of the direct path.

[0723] >For UM DRBs, for all PDCP SDUs that have been processed by PDCP but not yet submitted to lower layers, the sending of PDCP SDUs to the RLC entity associated with the direct path in DL, UL or SL is performed in ascending order of COUNT values ​​as specified below:

[0724] - Perform header compression of PDCP SDU using ROHC

[0725] - Perform integrity protection and ciphering of the PDCP SDU using the COUNT value associated with this PDCP SDU

[0726] - Submit the resulting PDCP data PDUs to the corresponding RLC entity of the direct path in DL, UL or SL.

[0727] An AM RLC entity sends a STATUS PDU to its peer AM RLC entity in order to provide positive and / or negative acknowledgement of an RLC SDU (or part thereof).

[0728] A. Triggers for initiating STATUS reports include:

[0729] > Polling from its peer AM RLC entity:

[0730] - When receiving an AMD PDU with SN=x and the P field set to "1" from lower layers, the receiving side of the AM RLC entity shall:

[0731] If the AMD PDU is to be discarded as specified in clause 5.2.3.2.2; or

[0732] If x < RX_Highest_STATUS or x >= RX_Next + AM_Window_Size:

[0733] Trigger a STATUS report.

[0734] - Otherwise: Delay triggering the STATUS report until x < RX_Highest_STATUS or x >= RX_Next + AM_Window_Size.

[0735] Note 1: This ensures that the RLC status report is sent after HARQ reordering.

[0736] > Detect the reception failure of the AMD PDU

[0737] - When the t-reassembly expires, the receiving side of the AM RLC entity shall trigger a STATUS report.

[0738] > When receiving the release of the indirect path for multi-path configuration,

[0739] - The receiving side of the AM RLC entity for the indirect path in DL, UL or SL shall trigger a STATUS report.

[0740] Note 2: The expiration of t-reassembly triggers both the update of RX_Highest_STATUS and the triggering of the STATUS report, but the STATUS report shall be triggered after updating RX_Highest_STATUS.

[0741] When the STATUS report has been triggered, the receiving side of the AM RLC entity shall:

[0742] > If t-StatusProhibit is not running: At the first transmission opportunity indicated by the lower layer, construct a STATUS PDU and submit it to the lower layer.

[0743] > Otherwise: At the first transmission opportunity indicated by the lower layer after the expiration of t-StatusProhibit, construct a single STATUS PDU and submit it to the lower layer even if the status report is triggered several times while t-StatusProhibit is running.

[0744] When the STATUS PDU has been submitted to the lower layer, the receiving side of the AM RLC entity shall: Start t-StatusProhibit.

[0745] When constructing the STATUS PDU, the AM RLC entity shall:

[0746] >For the not yet fully received RLC SDUs with SN such that RX_Next <= SN < RX_Highest_Status, in ascending order of the SN of the RLC SDUs and in ascending order of the byte segments within the RLC SDU, starting from SN = RX_Next until the point where the resulting STATUS PDU still fits the total size of the RLC PDU indicated by the lower layer:

[0747] - For RLC SDUs with no not yet received byte segments:

[0748] Include in the STATUS PDU the NACK_SN set to the SN of the RLC SDU.

[0749] - For the consecutive sequence of not yet received byte segments of a partially received RLC SDU:

[0750] Include in the STATUS PDU the set of NACK_SN, SOstart, and SOend.

[0751] - For the consecutive sequence of not yet received RLC SDUs:

[0752] Include in the STATUS PDU the set of NACK_SN and NACK ranges;

[0753] If needed, include in the STATUS PDU a pair of SOstart and SOend.

[0754] - Set ACK_SN to the SN of the next not yet received RLC SDU not indicated as missing in the resulting STATUS PDU.

[0755] Upon receiving a STATUS report from the receiving RLC AM entity, the transmitting side of the AM RLC entity shall:

[0756] >If the STATUS report includes a positive or negative acknowledgement for an RLC SDU with a sequence number equal to POLL_SN:

[0757] - If t-PollRetransmit is running: Stop and reset the timer t-Poll_Retransmit used by the transmitting side of the AM RLC entity for retransmitting the poll.

[0758] - Consider the RLC SDU or RLC SDU segment for which a negative acknowledgement for retransmission was received.

[0759] 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:

[0760] >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.

[0761] - 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.

[0762] -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 the specified configuration or the default configuration.

[0763] >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.

[0764] >The specific type of signaling RB may always configure the direct path of the split bearer as the primary path (eg, according to a specified configuration or a default configuration). For example, the specific type of signaling RB may be SRB1 and / or SRB2.

[0765] 22. The relay UE may request modification or release of the indirect bearer and / or the indirect path 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 if one or more of the following conditions are met:

[0766] - 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)

[0767] - If the relaying UE cannot meet the QoS requirements of the relayed bearer / channel, such as the delay requirement or data rate requirement of the relayed bearer / channel

[0768] - If the relay UE establishes a PC5 unicast link with one or more remote UEs

[0769] - If the relay UE releases the PC5 unicast link with the remote UE

[0770] - 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)

[0771] - If a 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 used to relay the SL bearer

[0772] - If the SL bearer mapped to any established Uu / PC5 RLC channel is released by the remote UE and / or relay UE

[0773] - If the NAS layer of the relaying UE requests the addition, modification or release of indirect bearers and / or indirect paths of split bearers that can be configured with multipath operation.

[0774] The first UE information message includes one or more of the following items:

[0775] - an identifier of the relayed bearer / channel subject to the above modification or the above modification conditions, for example a bearer identification, a logical channel identification, a source identification or a destination identification of the relayed bearer / channel

[0776] - an identifier of the relayed bearer / channel subject to the above release or the above release conditions, for example a bearer identity, a logical channel identity, a source identity or a destination identity of the relayed bearer / channel

[0777] - Reasons related to the above modified conditions

[0778] 23. The remote UE may request modification or release of the indirect path of the indirect bearer and / or split bearer to the gNB and / or inform 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 if one or more of the following conditions are met:

[0779] - If the remote 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)

[0780] - If the remote UE cannot meet the QoS requirements of the relayed bearer / channel, such as the delay requirements or data rate requirements of the relayed bearer / channel

[0781] - If the remote UE establishes a PC5 unicast link with one or more relay UEs

[0782] - If the remote UE releases the PC5 unicast link with the relay UE

[0783] - 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)

[0784] - If a 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 used to relay the SL bearer

[0785] - If the SL bearer mapped to any established Uu / PC5 RLC channel is released by the remote UE and / or relay UE

[0786] - If the NAS layer of the remote UE requests the addition, modification or release of indirect bearers and / or indirect paths of split bearers that can be configured with multipath operation.

[0787] The second UE information message includes one or more of the following items:

[0788] - an identifier of the relayed bearer / channel subject to the above modification or the above modification conditions, for example a bearer identification, a logical channel identification, a source identification or a destination identification of the relayed bearer / channel

[0789] - an identifier of the relayed bearer / channel subject to the above release or the above release conditions, for example a bearer identity, a logical channel identity, a source identity or a destination identity of the relayed bearer / channel

[0790] - Reasons related to the conditions of release mentioned above

[0791] 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 (see Table 6 to Table 10):

[0792] - Event X1 (serving L2 U2N relay UE becomes worse than threshold1 and NR cell becomes better than threshold2)

[0793] - Event X3 (the serving L2 U2N relay UE becomes worse than threshold1 and the PCell (or PSCell or SCell) becomes better than threshold2)

[0794] - Event X2 (serving L2 U2N relay UE becomes worse than threshold)

[0795] - Event Y2 (Candidate L2 U2N relay UE becomes better than threshold)

[0796] - Event C1 (NR side link channel busy ratio is higher than the threshold)

[0797] 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:

[0798] - Event C2 (NR side link channel busy ratio is lower than the threshold)

[0799] - Event Y1 (PCell becomes worse than threshold1 and candidate L2 U2N relay UE becomes better than threshold2)

[0800] If the relay UE considers that one of the following events is met based on the above measurement configuration, the relay UE initiates the second measurement report process:

[0801] - Event A2 (Service becomes worse than threshold)

[0802] - Event A3 (Neighbor becomes better offset than SpCell)

[0803] - Event B1 (Inter-RAT neighbor becomes better than threshold)

[0804] - Event B2 (PCell becomes worse than threshold1 and inter-RAT neighbors become better than threshold2)

[0805] - Event C1 (NR side link channel busy ratio is higher than the threshold)

[0806] 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.

[0807] - Event C2 (NR side link channel busy ratio is lower than the threshold)

[0808] - Event A1 (Service becomes better than threshold

[0809] If the first measurement reporting procedure is initiated, the remote UE notifies the gNB of the result of the measurement of the relay UE and the identifier of the relay UE by using the first measurement report.

[0810] If the second measurement reporting procedure is initiated, the relay UE notifies the gNB of the result of the measurement of the remote UE and the identifier of the remote UE by using the second measurement report.

[0811] 25. A CN node (e.g. AMF or SMF) may notify the gNB of the addition, modification or release of the multipath configuration, e.g. in the QoS profile for the remote UE and / or relay UE. The QoS profile is sent from the CN node to the gNB.

[0812] - The multipath related information in the QoS profile may indicate whether multipath can be configured for one of the following:

[0813] Each PDU session

[0814] Each QoS flow

[0815] Each remote UE

[0816] Each relay UE

[0817] Each frequency

[0818] Each community

[0819] Each RAT

[0820] Each PLMN

[0821] Each tracking area

[0822] Each gNB

[0823] 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 path of an indirect bearer and / or a split bearer for the relayed bearer / channel.

[0824] If the gNB determines the addition, modification or release of the indirect path of the indirect bearer and / or the split bearer for the relayed 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 (S169). The gNB may send the RRCReconfiguration message based on option 1 as described below for modification of the relayed bearer / channel, and send the RRCReconfiguration message based on option 2 as described below for release of the relayed bearer / channel.

[0825] - 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 of the remote UE.

[0826] -If the RRCReconfiguration message includes the SL-DestinationIdentity corresponding to the remote UE and the BearerIdentity or SL-DestinationIdentity corresponding to the indirect bearer or split bearer for the remote UE in s1-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 of the remote UE.

[0827] -If the RRCReconfiguration message includes (the SL-DestinationIdentity corresponding to the relay UE and) the BearerIdentity or SL-DestinationIdentity corresponding to the indirect bearer or split bearer for the remote UE in s1-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.

[0828] -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 of the relay UE. The remote UE may also add or modify a direct bearer to change an indirect / split bearer to a direct bearer.

[0829] A. Option 1: Joint RRC reconfiguration is used for remote UE and relay UE to modify or release indirect bearers and / or split bearers, possibly with the release of the U2N based connection.

[0830] The gNB sends an RRCReconfiguration message to the relay UE for modifying or releasing indirect bearers and / or split bearers, possibly accompanied by the release of the U2N-based connection via the relay UE. The RRCReconfiguration message includes at least a first part and a second part. The first part includes the indirect / split bearer related configuration applied to the relay UE, and the second part includes the indirect / split bearer related configuration applied to the remote UE. The second part may also include the direct bearer related configuration applied to the remote UE.

[0831] a. 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.

[0832] -For example, the second part is included in an RRC container of an 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. Upon 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 a PDCP layer, an SRAP layer, and an 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.

[0833] -Upon 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 reestablishment 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.

[0834] In case of RRC reestablishment procedure on Uu interface, the remote UE performs random access to the gNB and as a result of the procedure, only direct bearers are configured. In the RRC reestablishment procedure, the relay UE sends an RRCReestablishmentComplete message indicating failure of U2N configuration or multipath configuration along with the source or destination identity of the relay UE and / or remote UE.

[0835] 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 or destination identity of the relay UE and / or remote UE.

[0836] -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.

[0837] -When the PC5-RRC connection is released or when a sidelink relay reconfiguration failure or a multipath configuration failure is received, 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, when the PC5-RRC connection is released, when a sidelink relay reconfiguration failure or a multipath configuration failure is received or detected, 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. During the RRC reestablishment procedure, the relay UE performs random access to the gNB, and as a result of the procedure, only the direct bearer is configured. In the RRC re-establishment process, the relay UE sends an RRCReestablishmentComplete message indicating the failure of the U2N configuration or the multi-path configuration and the source or destination identity of the relay UE and / or the remote UE.

[0838] b. Option 1B: The relay UE forwards the second part to the remote UE by sending a PC5 RRC message (eg, RRCReconfigurationSidelink message or UuMessageTransferSidelink message) to the remote UE.

[0839] -For example, the second part is included in an RRC container of an RRCReconfiguration message or a UuMessageTransferSidelink 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 the first security key (or a second security key configured between the gNB and the remote UE). Upon 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 a 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 an RRCReconfigurationSidelink message sent to the remote UE. The second part may be included in the RRC container of the RRCReconfigurationSidelink message, or the second part is reconstructed to be included in the RRCReconfigurationSidelink message.

[0840] -Upon 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 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.

[0841] In case of RRC reestablishment procedure on Uu interface, the remote UE performs random access to the gNB and as a result of the procedure, only direct bearers are configured. In the RRC reestablishment procedure, the relay UE sends an RRCReestablishmentComplete message indicating failure of U2N configuration or multipath configuration along with the source or destination identity of the relay UE and / or remote UE.

[0842] 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 or destination identity of the relay UE and / or remote UE.

[0843] - Upon receiving an RRCReconfigurationFailureSidelink message, upon receiving a sidelink relay reconfiguration failure or a multipath configuration failure, upon detecting a sidelink failure (e.g., due to expiration of a timer T400), or if the relay UE fails to apply the first part of the configuration, the relay UE sends an RRCReconfigurationFailure or RRCReconfigurationComplete message failure of U2N configuration or multipath configuration to the gNB. Alternatively, upon receiving an RRCReconfigurationFailureSidelink message, upon receiving a sidelink relay reconfiguration failure or a multipath configuration failure, upon detecting a sidelink failure (e.g., due to expiration of a timer T400), or if the relay UE fails to apply the first part of the configuration, the relay UE initiates an RRC reestablishment procedure, 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 re-establishment procedure, the relay UE performs random access to the gNB and as a result of the procedure, only direct bearers are configured. During the RRC re-establishment procedure, the relay UE sends an RRCReestablishmentComplete message indicating the failure of U2N configuration or multipath configuration and the source or destination identity of the relay UE and / or remote UE.

[0844] In Option 1, when the remote UE or relay UE performs the RRC reestablishment procedure, it may also inform the gNB which UE failed to apply the U2N configuration or multipath configuration, i.e., the remote UE or relay UE.

[0845] 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, possibly accompanied by the release of the U2N based connection.

[0846] >The gNB sends a first RRCReconfiguration message to the relay UE for modification or release of an indirect bearer and / or a split bearer, possibly accompanied by release of a U2N-based connection via the relay UE. The first RRCReconfiguration message includes at least the indirect / split bearer related configuration applied to the relay UE.

[0847] -Upon 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, the relay UE initiates an RRC reestablishment procedure when the PC5-RRC connection is released, or when a sidelink relay reconfiguration failure or a multipath configuration failure is received or detected, 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. During the RRC reestablishment procedure, the relay UE performs random access to the gNB, and as a result of the procedure, only direct bearers are configured. During the RRC reestablishment procedure, the relay UE sends an RRCReestablishmentComplete message indicating a failure of U2N configuration or multipath configuration and a source or destination identity of the relay UE and / or the remote UE.

[0848] >The gNB sends a second RRCReconfiguration message to the remote UE for modification or release of indirect bearers and / or split bearers, possibly accompanied by release of the U2N-based connection via the relay UE. The second RRCReconfiguration message includes indirect / split bearer related configurations applied to the remote UE. The second RRCReconfiguration message may also include direct bearer related configurations applied to the remote UE.

[0849] - The gNB may send a second RRCReconfiguration message directly to the remote UE over the Uu interface, for example by using SRB1.

[0850] When 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 the U2N configuration or the multipath configuration to the gNB. The RRCReconfigurationComplete or RRCReconfigurationFailure message is sent directly to the gNB using SRB1, or is indirectly sent to the gNB via the relay UE using SL-RLC1 for SRB1. If the remote UE does not 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.

[0851] Alternatively, if the remote UE does not successfully apply the configuration of the second message, 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, and / or notify the relay UE of the sidelink relay reconfiguration failure or the multipath configuration failure. In the case of the RRC re-establishment procedure on the Uu interface, the remote UE performs random access to the gNB, and as a result of the procedure, only direct bearers are configured. In the RRC re-establishment procedure, the relay UE sends an RRCReestablishmentComplete message indicating the failure of the U2N configuration or multipath configuration and the source or destination identity of the relay UE and / or the remote UE. In the case of an RRC re-establishment procedure via a relay UE, the remote UE sends an RRCReestablishmentComplete message to the relay UE by using SL-RLC1 for SRB1, and the relay UE then forwards the RRCReestablishmentComplete message to the gNB. The RRCReestablishmentComplete message indicates the failure of U2N configuration or multipath configuration and the source or destination identity of the relay UE and / or remote UE.

[0852] Upon PC5-RRC connection release or upon receiving a sidelink relay reconfiguration failure or a multipath configuration failure, the relay UE fails to send an RRCReconfigurationFailure or RRCReconfigurationComplete message for U2N configuration or multipath configuration to the gNB. If an RRCReestablishmentRequest message is received from a 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.

[0853] Alternatively, upon PC5-RRC connection release, upon 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. During the RRC reestablishment procedure, the relay UE performs random access to the gNB, and as a result of the procedure, only direct bearers are configured. During the RRC reestablishment procedure, the relay UE sends an RRCReestablishmentComplete message indicating a failure of U2N configuration or multipath configuration and a source 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.

[0854] -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).

[0855] Upon 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, the relay UE does not forward the second RRCReconfiguration message received from the gNB to the remote UE when the PC5-RRC connection is released, or when a sidelink relay reconfiguration failure or a multipath configuration failure is received or detected, 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 a sidelink relay reconfiguration failure or a multipath configuration failure. During the RRC reestablishment procedure, the relay UE performs random access to the gNB, and as a result of the procedure, only direct bearers are configured. In the RRC re-establishment process, the relay UE sends an RRCReestablishmentComplete message indicating the failure of the U2N configuration or the multi-path configuration and the source or destination identity of the relay UE and / or the remote UE.

[0856] 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 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. In the case of the RRC reestablishment procedure on the Uu interface, the remote UE performs random access to the gNB, and as a result of the procedure, only direct bearers are configured. In the RRC reestablishment procedure, the relay UE sends an RRCReestablishmentComplete message indicating the failure of the U2N configuration or multipath configuration and the source or destination identity of the relay UE and / or the remote UE. In the case of the RRC reestablishment procedure via the relay UE, the remote UE sends the RRCReestablishmentComplete message to the relay UE by using SL-RLC1 for SRB1, and the relay UE then forwards the RRCReestablishmentComplete message to the gNB. The RRCReestablishmentComplete message indicates the failure of the U2N configuration or multipath configuration and the source or destination identity of the relay UE and / or the remote UE.

[0857] 27. In the above steps, the relay UE and the remote UE may release one or more or all of the 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 and release the indirect link via the relay UE and possible PC5-RRC connection with the relay UE.

[0858] For the release of the indirect path of the split bearer or the indirect bearer of the indirect path for multipath, the remote UE or the relay UE performs one or more of the following:

[0859] A. The receiving PDCP entity of the bearer in the remote UE may trigger the sending of a PDCP status report to the gNB as follows:

[0860] > Send PDCP status report from remote UE directly to gNB or indirectly via relay UE to gNB.

[0861] > Send PDCP status report from remote UE directly to gNB or indirectly via relay UE to gNB.

[0862] >Upon receipt of the PDCP Status Report, the transmitting PDCP entity for the bearer in the gNB triggers “Multi-Path Data Switching” to perform retransmission or transmission of the PDCP SDU on the direct path towards the remote UE as described below.

[0863] > Upon / before receiving the RRCReconfiguration message for the release of the bearer, or upon / 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:

[0864] -Opt 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.

[0865] -Opt 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 to the peer AM RLC entity in the relay UE.

[0866] -Opt 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 to the peer AM RLC entity in the relay UE.

[0867] >When 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.

[0868] B. The receiving PDCP entity of the bearer in the gNB may trigger a PDCP status report to the remote UE as follows:

[0869] > Send PDCP status report from gNB directly to remote UE or indirectly via relay UE.

[0870] > Upon receiving the PDCP Status Report, the transmitting PDCP entity of the bearer in the remote UE triggers “Multi-Path Data Switching” to perform retransmission or transmission of the PDCP SDU on the direct path towards the gNB as described below.

[0871] > Upon / before receiving the RRCReconfiguration message for the release of the bearer, or upon / before the release of the PC5-RRC connection, the SL RLC entity in the relay UE or remote UE may perform one or more of the following:

[0872] -Opt 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.

[0873] -Opt 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.

[0874] -Opt 3: For the SL RLC entity of the PC5 RLC channel of the uplink indirect path of the bearer, the AM RLC entity in the relay UE triggers an RLC STATUS report to the peer AM RLC entity in the remote UE.

[0875] >Upon receipt of 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 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.

[0876] -Upon 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 PC5-RRC connection or bearer.

[0877] >Afterwards, 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.

[0878] -Before / after reception of the UE INFORMATION message, the gNB releases the PDCP / RLC entity (or entities) corresponding to the bearer and / or PC5-RRC connection.

[0879] -The relay UE and / or remote UE releases the Uu / PC5PDCP / RLC entity (or multiple entities) corresponding to the bearer and / or PC5-RRC connection before / after sending the UE information message or when sending the RRCReconfiguration message to release the bearer to the remote UE and / or relay UE.

[0880] C. Upon / before receiving the RRCReconfiguration message for releasing the bearer, or upon / before releasing the PC5-RRC connection, for the downlink indirect path of the bearer, the relay UE stops any RLC status reporting process in the DL receiving RLC entity and / or the SL sending RLC entity, 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.

[0881] Using the disclosed invention, especially when the UE can support U2N relay function via SL, the network can configure multipath operation for relay UE and remote UE without loss or with minimal loss and release the indirect path of the multipath operation.

[0882] The invention is beneficial in that the system can properly provide multipath operation, including direct links and indirect links via U2N relays. In the prior art, there is no mechanism to provide multipath operation with sidelink relays.

[0883] Direct path addition over indirect paths for multipath operation

[0884] Hereinafter, a method of additionally configuring a direct path with a base station through an indirect path based on an RRC reconfiguration message and / or a method of forming both an indirect path and a direct path based on an RRC reconfiguration message will be described.

[0885] In addition, when a split radio bearer for direct and indirect is established based on an RRC reconfiguration message, a method of determining a primary path of a split radio bearer (hereinafter referred to as a split bearer) will be described in detail.

[0886] In addition, the following is based on the reference Fig.16 The contents described in subsections "1" to "27" of the description.

[0887] Fig.17 is a diagram for explaining a method for configuring a split bearer by a remote UE.

[0888] When the indirect path is configured for the remote UE, the remote UE may additionally configure the direct path through the U2N relay. Alternatively, the remote UE may configure the indirect path and the direct path at one time through an RRC reconfiguration message when the indirect path is connected (S171).

[0889] 1. The gNB may determine the multipath configuration based on the following information (S172).

[0890] >Opt 1: The remote UE (or relay UE) reports measurement information about the relay UE to the base station through a direct path or an indirect path.

[0891] >Opt 2: The remote UE reports the PC5-RRC connection establishment to the base station via the sidelink UE information.

[0892] -At this time, the sidelink UE information can be reported through the relay UE.

[0893] -Alternatively, if the relay UE (or remote UE) does not have a direct RRC connection, the remote UE (or relay UE) may first perform a RACH procedure and send the sidelink UE information directly to the base station.

[0894] >Opt 3: The relay UE reports PC5-RRC connection establishment via the sidelink UE information.

[0895] 2. The remote UE may perform cell reselection before performing the RACH procedure.

[0896] In the case of cell reselection as in the prior art, the PCell of the remote UE and the PCell of the relay UE may be different. For example, the remote UE may preferentially select the PCell of the relay UE through cell reselection. Alternatively, the remote UE may select the cell of the serving gNB of the relay through cell reselection. For example, the base station may instruct the remote UE to preferentially select the PCell of the relay UE.

[0897] In addition, the gNB can indicate the cell to be selected by the remote UE based on the measurement report of the relay UE or the remote UE.

[0898] 3. If the remote UE does not have a direct RRC connection, the RACH procedure (S173) may be performed as follows.

[0899] For example, the remote UE may send MSG3 or MSGA PUSCH of a RACH including a C-RNTI MAC CE.

[0900] >Alt 1: Paging based triggering of RACH procedure for remote UE

[0901] - The base station may send an indirect paging to the remote UE (via the relay UE). In this case, the paging may include the C-RNTI, s-TMSI of the remote UE, or may not include the UE ID. An indicator triggering the RACH (e.g., multipath in the paging cause) may be included in the paging message.

[0902] - Upon receiving the indirect paging, the remote UE performs a RACH to the base station.

[0903] - Alternatively, a remote UE supporting multipath may perform paging monitoring itself.

[0904] For example, the remote UE may perform paging monitoring by calculating the PO based on the C-RNTI.

[0905] Alternatively, similar to the paging operation of idle / inactive UEs, the remote UE may perform paging monitoring by calculating PO based on the s-TMSI.

[0906] >Alt 2: The RACH process of the remote UE can be triggered by the relay UE.

[0907] - The method for the relay UE to trigger the RACH transmission of the remote UE is as follows.

[0908] 2A: RACH process triggering using a specific field of the SCI

[0909] 2B: RACH process triggering using SL MAC CE

[0910] 2C: RACH process triggering using SL RRC message

[0911] >Alt 3: RRC connection establishment of relay UE can be triggered based on SIB / capability.

[0912] - For example, when the base station can configure multipath and the remote / relay UE supports multipath, the remote UE can start the RACH procedure.

[0913] For example, the base station may configure the multipath to the relay UE and / or the remote UE through SIB or dedicated RRC signaling. In this case, the remote UE may start the RACH process.

[0914] >Alt 4: When the base station sends the RRC reconfiguration message indirectly (as in the following process), the remote UE may trigger the RACH procedure before sending the RRC reconfiguration complete message. For example, the remote UE may use the triggering method of the RACH procedure of Alt 2.

[0915] 4. The base station may add a direct connection through an RRC reconfiguration process (S174).

[0916] -RRC reconfiguration is a message for direct or split bearers of remote UEs, but indirect bearers of relay UEs may need to be switched to direct or split bearers through RRC reconfiguration. Therefore, RRC reconfiguration messages for switching from indirect bearers to direct or split bearers may be defined separately. Alternatively, existing RRC reconfiguration messages may be used to instruct or configure switching from indirect bearers to direct or split bearers.

[0917] - Alternatively, even if the remote UE is already multipath connected, through RRC reconfiguration, bearer modification or radio reconfiguration is possible.

[0918] -For example, U2N bearers (i.e., Uu relay RLC channels and PC5 relay RLC channels) may not be set for a relay UE in connected mode and a remote UE that has established a PC5-RRC connection. In this case, the base station may configure the indirect path and direct path of the remote UE at one time through an RRC reconfiguration process.

[0919] -Here, the RRC reconfiguration process may be performed based on the method of RRC reconfiguration with Sync according to the setting of the base station. In this case, similar to the PCell change method, the remote UE may trigger a RACH procedure for sending an RRC reconfiguration complete message. In addition, the cell in which the remote UE performs the RACH procedure may be a target cell indicated by the RRC reconfiguration message.

[0920] Meanwhile, if the PCell of the remote UE and the PCell of the relay UE are configured differently, the RRC reconfiguration process may be performed in the same or similar manner as a method of simultaneously configuring a source cell and a target cell in a dual active protocol stack handover (DAPS HO).

[0921] Alternatively, the RRC reconfiguration message may indicate or configure a change in the primary path of the split bearer from an indirect path to a direct path. For example, when the primary path of a specific radio bearer is not set, the direct path among the indirect path and the direct path may be preferably set as the primary path.

[0922] Alternatively, for a specific type of SRB among multiple SRB types, the direct path may be preferably always set as the primary path. For example, the primary path of the split bearer is not set. In this case, when the type of the split bearer is SRB1 and / or SRB2, the primary path of the split bearer may be configured or determined as the direct path (default).

[0923] Here, multiple SRB types may include SRB0, SRB1, SRB2, and SRB3. SRB0 is used for RRC messages using the common control channel (CCCH) logical channel. SRB1 is used for RRC messages (which may include piggybacked NAS messages) and for NAS messages before the establishment of SRB2, all using the DCCH logical channel. SRB2 is used for NAS messages, all using the dedicated control channel (DCCH) logical channel. SRB2 has a lower priority than SRB1 and is always configured by the network after security activation. When the UE is in EN-DC, SRB3 is used for specific RRC messages, all using the DCCH logical channel.

[0924] Specifically, referring to the description in "21" above, the remote UE may receive an RRCReconfiguration message related to the configuration of the split bearer (split radio bearer) from the base station. The RRCReconfiguration message may not configure the primary path of the split bearer among the direct path and the indirect path. In this case, the remote UE may determine the primary path of the split bearer among the direct path and the indirect path based on the split bearer type.

[0925] For example, when the split bearer type is SRB1 or SRB2, the remote UE may always determine the direct path as the primary path. Alternatively, even if the indirect path is indicated as the primary path in the RRCReconfiguration message, the remote UE may always determine the direct path as the primary path for the split bearer of SRB1 or SRB2.

[0926] That is, the primary path of the split bearers SRB1 and SRB2 is always configured as a direct path.

[0927] 5. When the RRC reconfiguration process is completed, the gNB may exchange messages regarding modifications related to protocol data unit (PDU) sessions and bearers with the UPF and AMF (S175).

[0928] Hereinafter, a direct path through which a remote UE is directly connected to a base station or a network is defined as a first radio path, and an indirect path through which a remote UE is indirectly connected to a base station or a network through a relay UE is defined as a second radio path.

[0929] Fig.18 is a diagram for explaining a method for a remote UE to configure a split bearer for a multipath including a first radio path and a second radio path based on an RRC configuration message.

[0930] As reference Fig.16 As described, the remote UE may configure a second radio path indirectly connected to the network through the relay UE. Thereafter, the remote UE may report to the network, through the second radio path, quality information of the side link measurement for the relay UE configured for the second radio path. The network may send an RRC configuration message (or an RRC reconfiguration message) for adding the first radio path (the radio path via which the network and the remote UE are directly connected) to the remote UE based on the quality information.

[0931] Alternatively, the remote UE may send a request message to the network based on the quality information to additionally configure the first radio path for direct connection with the network. In this case, the remote UE may receive an RRC configuration message for additionally configuring the first radio path.

[0932] Reference Fig.18 , the remote UE may configure a split bearer for a multipath including a first radio path and a second radio path (S801). The remote UE may configure the split bearer based on a configuration message (e.g., an RRC configuration message or an RRC reconfiguration message) received from the network for configuring the split bearer of the first radio path and the second radio path. In addition, the remote UE may configure the multipath to which the first radio path is added by configuring the split bearer based on the RRC configuration message.

[0933] In addition, the remote UE needs to determine the main path of the split bearer to send the RRC message. Specifically, the remote UE can determine the main path among the first radio path and the second radio path based on the split bearer type. When the split bearer is SRB1 and / or SRB2, the remote UE can determine the main path of the split bearer as the first radio path. Here, SRB1 is an SRB for RRC messages using a dedicated control channel (DCCH) logical channel, and SRB2 is an SRB for non-access stratum (NAS) messages using a dedicated control channel (DCCH) logical channel. That is, when the type of the configured split bearer is a split bearer associated with SRB1 or SRB2, the remote UE can determine the first radio path as the main path for sending the RRC message even if there is no separate indication of the main path of the split bearer.

[0934] For example, when the split bearer is SRB1 and / or SRB2, the remote UE may always determine the primary path of the split bearer as the first radio path. In addition, when the split bearer is a data radio bearer (DRB) type, the remote UE may determine the primary path of the split bearer as the first radio path or the second radio path.

[0935] Alternatively, when the split bearer is SRB1 and / or SRB2, the RRC configuration message may always configure the primary path of the split bearer as the first radio path.

[0936] Alternatively, when the split bearer is SRB1 and / or SRB2, the primary path of the split bearer is determined to be the first radio path regardless of the primary path configured through the RRC configuration message.

[0937] Alternatively, if the RRC configuration message indicates the primary path as the second radio path, the remote UE determines the primary path as the first radio path of the split bearer associated with SRB1 or SRB2 regardless of the indication. Also, the remote UE may determine the primary path of another type of split bearer as the second radio path according to the RRC configuration message.

[0938] Next, when the configured split bearer is SRB1 or SRB2, the remote UE may send an RRC-related message to the network through the first radio path as the determined primary path (S803). For example, a message related to an RRC control message may always be sent and received through the first radio path as the primary path of the split bearer.

[0939] In this way, even if the split bearer for the first radio path and the second radio path is configured without indicating the primary path, the primary path for the split bearer of a specific SRB type can be clearly determined. That is, even if there is no indication of the RRC configuration message, the primary path of SRB1 or SRB2 related to the transmission of the RRC message can be clearly determined.

[0940] Furthermore, since the RRC configuration message for multi-path configuration does not need to separately indicate the primary path of the split bearer, the signaling load of the RRC configuration message related to the split bearer configuration of the multi-path can be minimized.

[0941] The various descriptions, functions, processes, proposals, methods and / or operational flowcharts of the present disclosure described herein may be applied without limitation to various fields requiring wireless communication / connection (5G) between devices.

[0942] 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.

[0943] Fig.19 A communication system applied to the present disclosure is illustrated.

[0944] Reference Fig.19, 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.

[0945] 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., side link 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.

[0946] 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 part of the resource allocation process can be performed based on various proposals of the present disclosure.

[0947] Fig. 20 A wireless device suitable for use with the present disclosure is illustrated.

[0948] Reference Fig. 20 , 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.19 {wireless device 100x and BS200} and / or {wireless device 100x and wireless device 100x} in.

[0949] 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 108. The processor 102 may control the memory 104 and / or the transceiver 106, and may be configured to implement the description, functions, processes, proposals, methods, and / or operation flowcharts 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 description, functions, processes, proposals, methods, and / or operation 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.

[0950] 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 16 to 18 At least one program for performing operations related to the described embodiments. For example, the memory 104 may include at least one program for receiving a radio resource control (RRC) message, the RRC message configuring a split bearer for a first radio path directly connected to the network and a second radio path indirectly connected to the network through a relay UE, and sending a message to the network through a primary path of the split bearer. Here, the primary path of the split bearer is determined by the first radio path based on an RRC configuration message configuring a split bearer related to a specific type of a signaling radio bearer (SRB).

[0951] 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.

[0952] 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.

[0953] 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.

[0954] 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.

[0955] 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.

[0956] 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.

[0957] Fig.21 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.19 ).

[0958] Reference Fig.21 , the wireless devices 100 and 200 may correspond to Fig. 20The 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. 20 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. 20 The control unit 120 is electrically connected to the communication unit 110, the memory 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.

[0959] 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.19 100a), vehicles ( Fig.19 100b-1 and 100b-2), XR devices ( Fig.19 100c), handheld device ( Fig.19 100d), household appliances ( Fig.19 100e), IoT devices ( Fig.19 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.19 400), BS( Fig.19 200), network nodes, etc. Depending on the use case / service, the wireless device can be used in a mobile or fixed place.

[0960] exist Fig.21In 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 memory 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.

[0961] Fig. 22 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.

[0962] Reference Fig. 22 , 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.21 Block 110 / 130 / 140.

[0963] 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.

[0964] 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.

[0965] 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.

[0966] 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.

[0967] 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.

[0968] 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.

[0969] 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.

[0970] 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.

[0971] Industrial Applicability

[0972] The present disclosure is applicable to UE, BS or other devices in a wireless mobile communication system.

Claims

1. A method for performing communication by a remote user equipment (UE) in a wireless communication system, the method comprising the following steps: configuring a split bearer, the split bearer comprising a first radio path directly connected to a network and a second radio path indirectly connected to the network through a relay UE; as well as Sending a radio resource control (RRC) message to the network through the primary path of the split bearer, When configuring the split bearer, based on the fact that the type of the split bearer is a specific type of a signaling radio bearer SRB that carries the RRC message, the primary path of the split bearer is determined to be the first radio path.

2. The method according to claim 1, further comprising the steps of: receiving an RRC configuration message for configuring the split bearer, The RRC configuration message for configuring the split bearer associated with a specific type of the SRB always configures the primary path as the first radio path.

3. The method according to claim 1, wherein: The specific type is SRB1 for a radio resource control RRC message using a dedicated control channel DCCH logical channel.

4. The method according to claim 1, wherein: The specific type is SRB2 for non-access stratum NAS messages using a dedicated control channel DCCH logical channel.

5. The method according to claim 1, further comprising the steps of: receiving an RRC configuration message for configuring the split bearer, The split bearer is configured based on the RRC configuration message without configuring the primary path, and the primary path of the split bearer is determined to be the first radio path.

6. The method according to claim 1, further comprising the steps of: receiving an RRC configuration message for configuring the split bearer, The primary path of the split bearer is determined to be the first radio path regardless of the primary path configured through the RRC configuration message.

7. The method according to claim 1, further comprising the steps of: receiving an RRC configuration message for configuring the split bearer, Wherein, the first radio path is added to the remote UE by configuring the split bearer based on the RRC configuration message.

8. The method according to claim 1, further comprising the steps of: receiving an RRC configuration message for configuring the split bearer, The type of the split bearer is a data radio bearer (DRB) type, and the primary path is determined as the second radio path based on the RRC configuration message.

9. The method according to claim 1, further comprising the steps of: receiving an RRC configuration message for configuring the split bearer, The RRC configuration message is received via the second radio path. 10 . A computer-readable medium storing instructions, which, when executed by a processor, cause the processor to execute the method according to claim 1 .

11. 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: configuring a split bearer, the split bearer comprising a first radio path directly connected to a network and a second radio path indirectly connected to the network through a relay UE; and Sending a radio resource control (RRC) message to the network through the primary path of the split bearer, When configuring the split bearer, based on the fact that the type of the split bearer is a specific type of a signaling radio bearer SRB that carries the RRC message, the primary path of the split bearer is determined to be the first radio path.

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

13. The device according to claim 11, wherein: The apparatus is a user equipment UE operating in a wireless communication system based on the 3rd Generation Partnership Project 3GPP.

14. A method for receiving a signal by a network in a wireless communication system, the method comprising the steps of: sending a radio resource control (RRC) configuration message, the RRC configuration message configuring a split bearer for a first radio path directly connected to a remote UE and a second radio path indirectly connected to the remote UE through a relay UE; as well as receiving a radio resource control (RRC) message from the remote UE via the primary path of the split bearer, Wherein, based on the type of the split bearer being a specific type of a signaling radio bearer SRB carrying the RRC message, the RRC message is received through the first radio path determined as the primary path.

15. A network for wireless communication, the network comprising: Transceiver; as well as a processor configured to control the transceiver, The processor is configured to send a radio resource control RRC configuration message, the RRC configuration message configuring a split bearer for a first radio path directly connected to a remote UE and a second radio path indirectly connected to the remote UE through a relay UE; and receive a radio resource control RRC message from the remote UE through a primary path of the split bearer, Wherein, based on the type of the split bearer being a specific type of a signaling radio bearer SRB carrying the RRC message, the RRC message is received through the first radio path determined as the primary path.

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