Connection control method for multi-hop sidelink relay operation and apparatus therefor

Abstract

The present disclosure relates to an operation technique for sidelink relay connection, and provides a connection control method of an intermediate relay terminal providing a multi-hop relay operation in a sidelink network, the method comprising the steps of: receiving system information for a multi-hop sidelink relay operation; and transmitting a discovery message, wherein the discovery message comprises at least one of information about whether the RRC is connected or not and hop count information of connection with the base station.

Description

Technical Field

[0001] This disclosure relates to an operational technique for sidelink relay connections. Background Technology

[0002] NR sidelink trunking operation allows for support of sidelink trunking in V2X, public safety, commercial application services, etc.

[0003] However, side-link relay operations only support single-hop side-link relay operations. In this type of single-hop side-link relay operation, there is only one relay terminal between the base station and the terminal. Considering the characteristics of relay operations, its applicability in applications is limited.

[0004] In situations where relay operations are required outside the base station's coverage area, multi-hop relay support is necessary. Specifically, it is required to define connection operations that utilize sidelink communication to support multi-hop relay operations. Summary of the Invention

[0005] The problem that the invention aims to solve

[0006] This disclosure provides a connection processing method and apparatus for performing multi-hop-based sidelink relay technology.

[0007] Solution for solving the problem

[0008] In one aspect, this embodiment can provide a connection control method for an intermediate relay terminal that provides multi-hop relay operation in a sidelink network. The method includes: receiving system information for multi-hop sidelink relay operation; and transmitting a discovery message, wherein the discovery message includes at least one of RRC connection information and hop count information connected to a base station.

[0009] In another aspect, this embodiment can provide a connection control method for a last relay terminal providing multi-hop relay operation in a sidelink network. The method includes: receiving system information for multi-hop sidelink relay operation from a base station; receiving a discovery request (solicitation) message from a sub-relay terminal; determining whether to transmit a discovery response message based on the discovery request message and the system information; and transmitting the discovery response message to the sub-relay terminal.

[0010] On the other hand, this embodiment can provide an intermediate relay terminal that performs connection control for multi-hop relay operation in a sidelink network. The intermediate relay terminal device includes: a receiving unit that receives system information for multi-hop sidelink relay operation; and a transmitting unit that transmits a discovery message, the discovery message including at least one of RRC connection information and hop count information connected to a base station.

[0011] On the other hand, this embodiment can provide a last relay terminal that performs connection control operations for multi-hop relay operations in a sidelink network. The last relay terminal device includes: a receiving unit that receives system information for multi-hop sidelink relay operations from a base station and receives a discovery request (solicitation) message from a sub-relay terminal; a control unit that determines whether to transmit a discovery response message based on the discovery request message and the system information; and a sending unit that transmits the discovery response message to the sub-relay terminal.

[0012] Invention Effects

[0013] According to this disclosure, a connection processing method and apparatus for performing multi-hop-based side link relay technology can be provided. Attached Figure Description

[0014] Figure 1 This is a diagram that simply illustrates the structure of an NR wireless communication system applicable to this embodiment.

[0015] Figure 2 This is a diagram used to illustrate the frame structure in an NR system to which this embodiment is applicable.

[0016] Figure 3 This is a diagram illustrating the resource grid that supports the wireless access technologies applicable to this embodiment.

[0017] Figure 4 This is a diagram illustrating the bandwidth portion that supports the wireless access technologies applicable to this embodiment.

[0018] Figure 5 This is an exemplary diagram illustrating a synchronization signal block in a wireless access technology to which this embodiment is applicable.

[0019] Figure 6 This is a diagram illustrating the random access process in the wireless access technology to which this embodiment is applicable.

[0020] Figure 7 This is a diagram used to illustrate CORESET.

[0021] Figure 8 This is a diagram illustrating a multi-hop relay structure of one embodiment.

[0022] Figure 9 This is a diagram illustrating the operation of an intermediate relay terminal in one embodiment.

[0023] Figure 10 This is a diagram illustrating the operation of the last relay terminal in one embodiment.

[0024] Figure 11 This is a diagram illustrating the structure of an intermediate relay terminal according to an embodiment.

[0025] Figure 12 This is a diagram illustrating the structure of the last relay terminal in one embodiment. Detailed Implementation

[0026] Hereinafter, some embodiments of the present disclosure will be described in detail with reference to the exemplary accompanying drawings. When assigning reference numerals to components in each drawing, the same components may be assigned the same symbols as much as possible, even if they are shown in different drawings. Furthermore, in describing these embodiments, detailed descriptions of related well-known structures or functions may be omitted if it is believed that such detailed descriptions would obscure the main idea of ​​the present invention. In this specification, the terms "comprising," "having," and "forming" indicate that other parts may be added, unless "only" is used. When a component is represented as a singular, it may include a plural case unless specifically and explicitly stated otherwise.

[0027] Furthermore, in describing the components of this disclosure, terms such as first, second, A, B, (a), and (b) may be used. These terms are only for distinguishing the component from other components, and the nature, order, sequence, or number of the components are not limited by these terms.

[0028] In the description of component positional relationships, if two or more components are described as "connected," "combined," or "accessed," then the two or more components can be directly "connected," "combined," or "accessed." However, it should be understood that other components can also "intervene" into two or more components, thereby "connecting," "combining," or "accessing." Furthermore, these other components can be included within one or more of the two or more components that are mutually "connected," "combined," or "accessed."

[0029] In descriptions of time-series relationships related to components, operating methods, or production methods, when using terms such as "after," "following," "next," or "before" to indicate the sequence of time or processes, discontinuous situations may be included unless "immediately" or "directly" is used.

[0030] On the other hand, when referring to the numerical values ​​of components or their corresponding information (e.g., grades), even if not explicitly stated separately, the numerical values ​​or their corresponding information should be interpreted as including the range of errors that may arise due to various factors (e.g., process factors, internal or external shocks, noise, etc.).

[0031] The wireless communication system in this specification refers to a system that utilizes wireless resources to provide various communication services such as voice and data packets. This system may include terminals, base stations, or core networks.

[0032] The embodiments disclosed below are applicable to wireless communication systems using various wireless access technologies. For example, these embodiments are applicable to various wireless access technologies, such as CDMA (code division multiple access), FDMA (frequency division multiple access), TDMA (time division multiple access), OFDMA (orthogonal frequency division multiple access), SC-FDMA (single carrier frequency division multiple access), or NOMA (non-orthogonal multiple access). Furthermore, wireless access technology not only refers to a specific access technology but can also refer to various generations of communication technologies specified by different communication protocol organizations, such as 3GPP, 3GPP2, WiFi, Bluetooth, IEEE, ITU, etc. For example, CDMA can be implemented through wireless technologies such as UTRA (universal terrestrial radio access) or CDMA2000. TDMA can be implemented using wireless technologies such as GSM (Global System for Mobile Communications), GPRS (General Packet Radio Service), and EDGE (Enhanced Data Rates for GSM Evolution). OFDMA can be implemented using wireless technologies such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, and E-UTRA (evolved UTRA). IEEE 802.16m, as an evolution of IEEE 802.16e, provides backward compatibility with IEEE 802.16e-based systems. UTRA is part of UMTS (Universal Mobile Telecommunications System).3GPP (3rd Generation Partnership Project) LTE (Long Term Evolution) is part of E-UMTS (evolved UMTS), which uses E-UTRA (evolved-UMTS terrestrial radio access). It employs OFDMA in the downlink and SC-FDMA in the uplink. As described above, this embodiment can be applied to currently available or commercially available radio access technologies, as well as those currently under development or in the future.

[0033] On the other hand, the term "terminal" in this specification is a general concept, referring to a device that includes a wireless communication module communicating with a base station in a wireless communication system. It should be interpreted as including not only UEs (User Equipment) in WCDMA (Wideband Code Division Multiple Access), LTE, NR (New Radio), HSPA (High-Speed ​​Packet Access), and IMT-2020 (5G or New Radio), but also MS (Mobile Station), UT (User Terminal), SS (Subscriber Station), and wireless devices in GSM. Furthermore, depending on its usage, a terminal can be a user-portable device such as a smartphone. In V2X (vehicle to everything) communication systems, it can also mean a vehicle, including devices containing in-vehicle wireless communication modules. Additionally, in machine-type communication systems, it can also mean an MTC terminal, an M2M (Machine to machine) terminal, and a URLLC (Ultra-Reliable Low-Latency Communications) terminal equipped with a communication module to perform machine-type communication.

[0034] In this specification, "base station" or "cell" refers to a terminal that communicates with the terminal in terms of the network. This encompasses various coverage areas, such as: Node-B, eNB (evolved Node-B), gNB (gNode-B), LPN (Low Power Node), sector, site, various types of antennas, BTS (Base Transceiver System), access point, point (e.g., transmission point, reception point, transmit / receive point), relay node, extra-large cell, macro cell, micro cell, pico cell, femtocell, RRH (Remote Radio Head), RU (Radio Unit), small cell, etc. Furthermore, a cell can also refer to the BWP (Bandwidth Part) in the frequency domain. For example, a serving cell can refer to the terminal's activation BWP.

[0035] Since the various types of cells listed above have base stations controlling more than one cell, a base station can be interpreted in two ways. It can indicate: (1) the device itself that provides a large-scale cell, macro cell, micro cell, pico cell, femtocell, or small cell associated with the wireless area; and (2) the wireless area itself. In case (1), all devices that interact to enable the provision of a specified wireless area to be controlled by the same object or that configure the wireless area through cooperation are indicated as base stations. Depending on the configuration of the wireless area, one embodiment of a base station is: a point, a transmitting / receiving point, a transmission point, a receiving point, etc. In case (2), the wireless area that receives or transmits signals can also be indicated as a base station from the perspective of the user terminal or from the perspective of an adjacent base station.

[0036] In this specification, a cell can refer to the coverage area of ​​signals transmitted from a transmission / reception point, or the coverage area of ​​signals transmitted from a transmission / reception point, a component carrier, or the transmission / reception point itself.

[0037] Uplink (UL, or uplink) refers to the way data is sent / received from a terminal to a base station, while downlink (DL, or downlink) refers to the way data is sent / received from a base station to a terminal. Downlink can refer to a communication or communication path from multiple sender / receiver points to the terminal, and uplink can refer to a communication or communication path from the terminal to multiple sender / receiver points. In downlink, the transmitter can be part of multiple sender / receiver points, and the receiver can be part of the terminal. Similarly, in uplink, the transmitter can be part of the terminal, and the receiver can be part of multiple sender / receiver points.

[0038] Uplink and downlink transmit / receive control information through control channels such as PDCCH (Physical Downlink Control Channel) and PUCCH (Physical Uplink Control Channel); and transmit / receive data through data channels such as PDSCH (Physical Downlink Shared Channel) and PUSCH (Physical Uplink Shared Channel). Hereinafter, the transmission / reception of signals through channels such as PUCCH, PUSCH, PDCCH, and PDSCH will be labeled as "transmitting / receiving PUCCH, PUSCH, PDCCH, and PDSCH".

[0039] To illustrate this more clearly, the following description focuses on the 3GPP LTE / LTE-A / NR (New RAT) communication system, but the technical features are not limited to this communication system.

[0040] Within 3GPP, after studying 4G (4th-Generation) communication technology, the focus shifted to developing 5G (5th-Generation) communication technology that complies with the requirements of ITU-R's next-generation radio access technology. Specifically, 3GPP is developing new NR communication technology through 5G, which differs from LTE-A pro and 4G communication technologies, which are improvements to LTE-Advanced technology in accordance with ITU-R requirements. While both LTE-A pro and NR represent 5G communication technology, the following explanation of 5G communication technology will focus on NR unless otherwise specified.

[0041] The operational scenarios in NR, in addition to the existing 4G LTE scenarios, incorporate considerations such as satellite, automotive, and new vertical technologies, and define a variety of operational scenarios. In terms of service, it supports eMBB (Enhanced Mobile Broadband) scenarios; mMTC (Massive Machine Communication) scenarios, which have high terminal density and are deployed over a wide area, requiring low data rates and asynchronous access; and URLLC (Ultra Reliability and Low Latency) scenarios, which require high responsiveness and reliability, and can support high-speed mobility.

[0042] To meet these needs, NR discloses a wireless communication system that incorporates new waveform and frame structure technologies, low latency technologies, mmWave support technologies, and forward-compatible technologies. In particular, the NR system introduces several technical variations to provide flexibility and forward compatibility. The main technical features of NR will be described below with reference to the accompanying drawings.

[0043] <Typical NR System>

[0044] Figure 1 This is a diagram that simply illustrates the structure of an NR system applicable to this embodiment.

[0045] Reference Figure 1, the NR system is divided into 5GC (5G Core Network) and NR-RAN (New Radio Radio Access Network) parts. NG-RAN (Next Generation Radio Access Network) consists of gNB and ng-eNB that provide the user plane (SDAP (Service Data Adaptation Protocol) / PDCP (Packet Data Convergence Protocol) / RLC (Radio Link Control) / MAC (Medium Access Control) / PHY (Physical Layer)) and the control plane (RRC) protocol termination for the UE (User Equipment). gNBs are interconnected with each other or with ng-eNBs via the Xn interface. gNB and ng-eNB are connected to 5GC via the NG interface respectively. 5GC may include: AMF (Access and Mobility Management Function), which is responsible for the control plane such as terminal access and mobility control functions; and UPF (User Plane Function), which is responsible for user data control functions. NR supports both frequency bands below 6 GHz (FR1, Frequency Range 1) and above 6 GHz (FR2, Frequency Range 2).

[0046] gNB means a base station that provides the NR user plane and control plane protocol termination to the terminal, and ng-eNB means a base station that provides the E-UTRA user plane and control plane protocol termination to the terminal. The base stations described in this specification should be understood to cover the meanings of gNB and ng-eNB, and can also be used according to the meaning of differentiating gNB or ng-eNB as needed.

[0047] <Waveforms, Parameter Sets, and Frame Structures in NR>

[0048] In NR, for downlink transmission, the CP-OFDM (Cyclic prefix Orthogonal Frequency Division Multiplexing) waveform with Cyclic prefix is used, and for uplink transmission, CP-OFDM or DFT-s-OFDM (Discrete Fourier Transform Spread Orthogonal Frequency Division Multiplexing) is used. The OFDM technology is easy to combine with MIMO (Multiple Input Multiple Output), and its advantages are high frequency efficiency and the ability to use a receiver with low complexity.

[0049] On the other hand, in NR, since the requirements for data speed, latency, coverage, etc., differ for the three scenarios mentioned above, it is necessary to effectively meet the requirements of each scenario by using the frequency bands that make up any NR system. To this end, a technique for effectively multiplexing radio resources based on different multiple parameter sets (numerology) is proposed.

[0050] Specifically, the NR transmission parameter set is determined based on the sub-carrier spacing and CP (Cyclic prefix), as shown in Table 1 below. With 15kHz as the reference, the μ value is used as an exponent of 2 and varies exponentially.

[0051] Table 1

[0052]

[0053] As shown in Table 1 above, the parameter set of NR can be divided into five types according to the subcarrier spacing. This differs from LTE, one of the 4G communication technologies, where the subcarrier spacing is fixed at 15kHz. Specifically, the subcarrier spacing used for data transmission in NR is 15kHz, 30kHz, 60kHz, and 120kHz, while the subcarrier spacing used for synchronization signal transmission is 15kHz, 30kHz, 120kHz, and 240kHz. Furthermore, Extended CP is only applicable to a 60kHz subcarrier spacing. On the other hand, the frame structure in NR defines a frame with a length of 10ms, which consists of 10 subframes of the same length (1ms). A frame can be divided into 5ms half-frames, each half-frame comprising 5 subframes. In the case of a 15kHz subcarrier spacing, a subframe consists of one slot, and each slot consists of 14 OFDM symbols.

[0054] Figure 2 This is a diagram used to illustrate the frame structure in an NR system to which this embodiment is applicable.

[0055] Reference Figure 2 In normal CP (Concurrent Frame) configurations, a time slot consists of a fixed 14 OFDM symbols. However, the time slot length can vary depending on the subcarrier spacing. For example, with a parameter set having a 15kHz subcarrier spacing, the time slot length is 1ms, the same as the subframe length. Conversely, with a parameter set having a 30kHz subcarrier spacing, although the time slot consists of 14 OFDM symbols, its length is 0.5ms, allowing two time slots to be contained within a single subframe. That is, subframes and frames are defined by a fixed time length, while time slots are defined by the number of symbols, and their time length can vary depending on the subcarrier spacing.

[0056] In addition, the basic unit of scheduling in NR is defined as a time slot. To reduce the transmission delay in the radio interval, mini-slots (or sub-slots or non-slot based schedule) are also introduced. If a wide subcarrier spacing is used, the length of a time slot will become shorter inversely, so the transmission delay in the radio interval can be reduced. Mini-slots (or sub-slots) are used to effectively support the URLLC scenario and can be scheduled in units of 2, 4, or 7 symbols.

[0057] In addition, different from LTE, NR defines the uplink and downlink resource allocation as the symbol level within a time slot. To reduce the HARQ (Hybrid Automatic Repeat Request) delay, a time slot structure that can directly send HARQ ACK / NACK (Hybrid Automatic Repeat Request - Acknowledgment / Negation) within the transmission time slot is defined, and this time slot structure is named a self-contained structure for explanation.

[0058] In NR, it is designed to support a total of 256 time slot formats, of which 62 time slot formats are used for 3GPP Rel-15. In addition, through various combinations of time slots, it supports the common frame structure that composes the FDD or TDD frame. For example, it supports the time slot structure where all symbols of the time slot are set as downlink, the time slot structure where all symbols are set as uplink, and the time slot structure where downlink symbols and uplink symbols are combined. In addition, NR supports scheduling data transmission scattered in more than one time slot. Therefore, the base station can use the Slot Format Indicator (SFI) to notify the terminal whether the time slot is a downlink time slot, an uplink time slot, or a flexible time slot. The base station can use the SFI indication to form a table index through UE-specific RRC signaling to indicate the time slot format, or can perform dynamic indication through DCI (Downlink Control Information) or static or quasi-static indication through RRC.

[0059] <Physical Resources in NR>

[0060] Regarding the physical resources in NR, antenna ports, resource grids, resource elements, resource blocks, bandwidth parts, etc. can be considered.

[0061] An antenna port is defined as a channel carrying symbols on an antenna port that can be inferred from channels carrying other symbols on the same antenna port. If the large-scale property of a channel carrying symbols on one antenna port can be inferred from a channel carrying symbols on another antenna port, then the two antenna ports can be considered to have a QC / QCL (quasico-located or quasico-location) relationship. The large-scale property includes one or more of the following: delay spread, Doppler spread, frequency shift, average received power, and received timing.

[0062] Figure 3 This is a diagram illustrating the resource grid that supports the wireless access technologies applicable to this embodiment.

[0063] Reference Figure 3 For the resource grid, since NR supports multiple parameter sets within the same carrier, the resource grid can exist for each parameter set. Furthermore, the resource grid can exist based on antenna ports, subcarrier spacing, and transmission direction.

[0064] A resource block consists of 12 subcarriers and is defined only in the frequency domain. Furthermore, a resource element consists of one OFDM symbol and one subcarrier. Therefore, as... Figure 3 As shown, the size of a resource block can vary depending on the subcarrier spacing. Furthermore, NR defines "Point A," which serves as a common reference point for the resource block grid, as well as common resource blocks, virtual resource blocks, etc.

[0065] Figure 4 This is a diagram illustrating the bandwidth portion that supports the wireless access technologies applicable to this embodiment.

[0066] In NR, unlike LTE where the carrier bandwidth is fixed at 20MHz, the maximum carrier bandwidth for each subcarrier interval is set to 50MHz to 400MHz. Therefore, it is not assumed that all terminals use these carrier bandwidths. Thus, in NR, as... Figure 4As shown, a bandwidth part (BWP) can be specified within the carrier bandwidth for use by a terminal. In addition, the bandwidth part is associated with a parameter set, consists of a subset of contiguous common resource blocks, and can be dynamically activated over time. The terminal is configured to have up to 4 bandwidth parts for the uplink and downlink respectively, and transmits / receives data using the activated bandwidth part within a specified time.

[0067] In the case of a paired spectrum, the uplink and downlink bandwidth parts are set independently. In the case of an unpaired spectrum, to prevent unnecessary frequency re-tuning between downlink and uplink operations, the downlink and uplink bandwidth parts are paired to share the center frequency.

[0068] <Initial Access in NR>

[0069] In NR, for a terminal to access a base station for communication, it performs a cell search and a random access procedure.

[0070] Cell search is a procedure that uses the synchronization signal block (SSB, Synchronization Signal Block) transmitted by a base station to synchronize the terminal with the cell of the above base station, obtain the physical layer cell ID, and obtain system information.

[0071] Figure 5 It is a diagram exemplarily showing the synchronization signal block in the radio access technology applicable to this embodiment.

[0072] Refer to Figure 5 , the SSB consists of a PSS (primary synchronization signal), which occupies 1 symbol and 127 subcarriers, an SSS (secondary synchronization signal), which also occupies 1 symbol and 127 subcarriers, and a PBCH that spans 3 OFDM symbols and 240 subcarriers.

[0073] The terminal receives the SSB by monitoring the SSB in the time and frequency domains.

[0074] A maximum of 64 SSBs can be transmitted within 5ms. Most SSBs are transmitted using different beams within this 5ms period. If the terminal uses a specific beam for transmission as a reference, it is assumed that an SSB is transmitted once every 20ms, and detection is performed. The number of beams available for SSB transmission within 5ms increases with frequency band. For example, a maximum of 4 SSB beams can be transmitted below 3GHz, a maximum of 8 can be used in the 3GHz–6GHz band, and a maximum of 64 different beams can be used to transmit SSBs above 6GHz.

[0075] The SSB comprises two in a time slot, and the starting symbol and repetition number within the time slot are determined according to the subcarrier spacing as described below.

[0076] On the other hand, unlike existing LTE SS (Signal Stream), SSB (Signal Stream Bus) is not transmitted at the center frequency of the carrier bandwidth. That is, SSBs can be transmitted outside the system band center, and multiple SSBs can be transmitted in the frequency domain when broadband operation is supported. Therefore, the terminal uses a synchronization raster, which serves as a candidate frequency location for monitoring SSBs, to monitor them. In NR, the carrier raster and synchronization raster are redefined as the center frequency locations of the channels used for initial access, and the synchronization raster has a wider frequency spacing compared to the carrier raster, thus supporting faster SSB search by the terminal.

[0077] The terminal can obtain the MIB (Master Information Block) through the PBCH of the SSB. The MIB includes the minimum information used by the terminal to receive the Remaining Minimum System Information (RMSI) broadcast by the network. In addition, the PBCH may include: location information for the first DM-RS symbol in the time domain; information used by the terminal to monitor SIB1 (e.g., SIB1 parameter set information, information related to the SIB1 CORESET, search space information, and PDCCH-related parameter information); offset information between the common resource block and the SSB (the absolute position of the SSB in the carrier is transmitted via SIB1); and so on. The SIB1 parameter set information is also applicable to some messages used in the random access procedure for accessing the base station after the terminal completes the cell search procedure. For example, the SIB1 parameter set information may be applicable to at least one of messages 1 to 4 used in the random access procedure.

[0078] The aforementioned RMSI can refer to SIB1 (System Information Block 1), which is broadcast periodically (e.g., every 160ms) within the cell. SIB1 includes information required for the terminal to perform the initial random access procedure and is periodically transmitted via the PDSCH. To receive SIB1, the terminal needs to receive parameter set information for SIB1 transmission and CORESET (Control Resource Set) information for SIB1 scheduling via the PBCH. Within the CORESET, the terminal uses SI-RNTI to confirm the scheduling information for SIB1 and retrieves SIB1 from the PDSCH based on the scheduling information. Other SIBs besides SIB1 can be transmitted periodically or upon request from the terminal.

[0079] Figure 6 This is a diagram illustrating the random access process in the wireless access technology to which this embodiment is applicable.

[0080] Reference Figure 6 Upon completion of cell search, the terminal transmits a random access preamble to the base station for random access. The random access preamble is transmitted via PRACH. Specifically, the random access preamble is transmitted to the base station via PRACH consisting of consecutive radio resources in a periodically repeated specific time slot. Typically, when the terminal initially accesses a cell, a contention-based random access procedure is executed, and when random access is performed for Beam Failure Recovery (BFR), a non-contention-based random access procedure is executed.

[0081] The terminal receives a random access response to the transmitted random access preamble. The random access response may include: a random access preamble identifier (ID), a UL Grant (UL authorization) (uplink radio resources), a temporary C-RNTI (Temporary Cell-Radio Network Temporary Identifier), and a TAC (Time Alignment Command). Since a random access response may include random access response information for more than one terminal, a random access preamble identifier may be included to notify which terminal the included UL Grant, temporary C-RNTI, and TAC are valid for. The random access preamble identifier may be an identifier for the random access preamble received by the base station. The TAC may be included as information for the terminal to adjust uplink synchronization. The random access response may be indicated by a random access identifier on the PDCCH, i.e., RA-RNTI (Random Access-Radio Network Temporary Identifier).

[0082] The terminal that receives a valid random access response processes the information contained in the random access response and performs a transmission scheduled to the base station. For example, the terminal applies the TAC and stores the temporary C-RNTI. Additionally, the data stored in the terminal buffer or newly generated data is transmitted to the base station using the UL Grant. In this case, information capable of identifying the terminal should be included.

[0083] Finally, the terminal receives a downlink message for contention resolution.

[0084] <CORESET in NR>

[0085] The downlink control channel in NR is transmitted by a CORESET (Control Resource Set) with a length of 1 to 3 symbols, and transmits uplink / downlink scheduling information, SFI (Slot format Index), TPC (Transmit Power Control) information, etc.

[0086] As mentioned above, NR introduces the concept of CORESET to ensure system flexibility. CORESET (Control Resource Set) refers to the time-frequency resources (i.e., real-frequency resources) used for downlink control signals. Terminals can use more than one search space within the CORESET time-frequency resources to decode control channel candidates. A QCL (Quasi CoLocation) hypothesis is set for each CORESET, the purpose of which is to inform, in addition to the characteristics based on the existing QCL hypothesis—delay spread, Doppler spread, Doppler shift, and average delay—the characteristics for the analog beam direction as well.

[0087] Figure 7 This is a diagram used to illustrate CORESET.

[0088] Reference Figure 7 A CORESET can exist in various forms within a carrier bandwidth of a single time slot. In the time domain, a CORESET can consist of up to three OFDM symbols. Furthermore, in the frequency domain, a CORESET is defined as a multiple of six resource blocks, up to the carrier bandwidth.

[0089] The first CORESET, as part of the initial bandwidth component, is indicated via MIB to receive additional configuration and system information from the network. After establishing a connection with the base station, the terminal can receive and configure more than one CORESET via RRC signaling.

[0090] In this specification, frequencies, frames, subframes, resources, resource blocks, regions, frequency bands, subbands, control channels, data channels, synchronization signals, various reference signals, various signals, or various messages related to NR (New Radio) may be interpreted in the sense of their past or present use or in the sense of their future use.

[0091] This disclosure relates to a relay terminal connection control method and apparatus for supporting multi-hop sideline relay.

[0092] In 3GPP, Rel-17 and Rel-18 standardized NR sidelink (SL) relay projects, specifying NR sidelink-based relay functionality. This enables sidelink relay in V2X, public safety, and commercial application services. However, existing NR sidelink relay is limited to single-hop relay, thus restricting its application adaptability. To address this issue, multi-hop relay functionality is needed, but no specific technology is provided for this. In particular, existing mobile communication technologies do not offer connection support methods for multi-hop sidelink relay.

[0093] This embodiment, created to address this problem, proposes a relay terminal connection control method and apparatus for transmitting data to or receiving data from a base station via a multi-hop relay terminal based on an NR-side crosslink. The method includes a relay selection method.

[0094] The following describes a data processing method based on 5GS / NR technology. However, this is only for illustrative purposes, and the present invention is equally applicable to any system / wireless access technology (e.g., LTE, 6G). The embodiments described in this invention include information elements and operational content specified in NR / 5GS specifications (e.g., MAC specification: TS 38.321, NR RRC specification: TS 38.331, system architecture specification: TS23.501, etc.). Even if terminal operational content related to the definitions of the above information elements is not included in this specification, the relevant content specified in the standard specifications is included in this invention.

[0095] Any of the functions described below are defined as individual terminal capabilities (UE radio capabilities or UE core network capabilities) and can be transmitted by the terminal / device to the base station / core network object (e.g., AMF / SMF) via the aforementioned signaling. Alternatively, any functions can be combined / integrated and defined as the aforementioned terminal capabilities, and can be transmitted by the terminal to the base station / core network object via the aforementioned signaling.

[0096] For any function or combination of functions described below, the base station may transmit / indicate to the terminal, via any downlink message (e.g., RRC message, MAC control element, MAC PDU, system information), information indicating the permission / support / configuration of the aforementioned function / function combination. For example, this information may be indicated to the terminal before or during the configuration / application of the aforementioned function / function combination. The aforementioned message may be broadcast within the aforementioned area. The aforementioned message may be transmitted to a single terminal within the aforementioned area (unicast). The aforementioned message may be transmitted to a group of UEs within the aforementioned area (multicast).

[0097] The base station can transmit / indicate information for restricting / controlling any of the functions described below to the terminal via any downlink message (e.g., RRC message, MAC control element, MAC PDU). For example, a prohibit timer for the aforementioned function can be indicated. The prohibit timer can be started / restarted before or during the activation of the aforementioned function. During the operation of the aforementioned timer, the terminal can restrict / control the function in a manner that prevents it from being activated / executed. For example, the aforementioned function / function combination can be indicated to the terminal before or during the configuration / application of the aforementioned function / function combination. The aforementioned message can be broadcast within the aforementioned area. The aforementioned message can be transmitted to a single terminal within the aforementioned area (unicast). The aforementioned message can be transmitted to a group of UEs within the aforementioned area (multicast).

[0098] The embodiments and functions described below can be performed additionally or independently. The embodiments and related operations described below can be combined / integrated with any embodiments and related operations, and it is obvious that this is also included within the scope of this invention. The related operations of any embodiment can be implemented in different orders.

[0099] Any information described below can be traffic characteristics information obtained / calculated / induced statistically / empirically in the terminal / network (e.g., expected value / average, deviation, standard deviation, minimum, maximum, etc., any statistical / statistical quantity). Therefore, any information contained in this specification can represent one or more of the average (expected value), minimum, maximum, or standard deviation values. For ease of explanation, all information in this specification can be used as statistical information. Any information described below can be information pre-configured in the terminal / network or pre-configured via OAM / application server / application function / UDM.

[0100] Definition of relay terminal functions for multi-hop sidelink relay support

[0101] In NR technology, to support single-hop side-link relay, two terminals are defined: a remote terminal and a relay terminal. The remote terminal (UE-to-Network, U2N) is a UE that communicates with the network via a U2N Relay UE. The U2N Relay terminal provides functionality to support connectivity to the network for U2NRemote UE(s). To indicate the UE capabilities of these two terminals, relay terminal operation capability (relayUE-Operation-L2-r17) and remote terminal operation capability (remoteUE-Operation-L2-r17) are defined.

[0102] Sidelink relay supports relaying via sidelink relay terminals consisting of single hops. Therefore, a terminal operating as a sidelink remote terminal cannot provide sidelink relay terminal functionality simultaneously. Sidelink relay terminals provide U2N relay discovery services that allow discovery by remote terminals, access to 5G systems as a terminal, and unicast traffic relay functionality between remote terminals and base stations. Single-hop sidelink relay is provided between remote terminals and base stations via a sidelink relay (e.g., a U2N relay terminal). For ease of illustration, in the following text, L2 / L3 U2N remote terminals (or End terminals) that are to access networks based on more than one sidelink relay are labeled as remote terminals.

[0103] Multi-hop sidelink relay requires relaying between remote terminals and base stations via relay terminals based on multiple sidelinks. Therefore, it is difficult to provide multi-hop operation using only existing sidelink relay terminals (or the aforementioned functions). To support multi-hop sidelink relay, it is necessary to define the sidelink-based relay terminals (or the aforementioned functions or functional entities) separately.

[0104] Figure 8 This is a diagram illustrating a multi-hop relay structure of one embodiment.

[0105] Reference Figure 8 Multi-hop relay refers to a network in which two or more relay terminals 801, 802, and 803 transmit data over a communication line between base station 800 and remote terminal 810.

[0106] In cases involving two or more relay terminals, the relay terminal 801 connected to the base station via the Uu interface may be described as the last relay terminal. For example, the sidelink relay terminal connected to the base station 800 via the Uu interface and connected to other sidelink relay terminals via the PC5 interface may be described as the last relay terminal 801.

[0107] One or more side-link relay terminals 802 and 803 located between the last relay terminal 801 and the remote terminal 810 will be described as intermediate relay terminals. Furthermore, among the side-link relay terminals, the first relay terminal connected to the remote terminal 810 will be described as the first relay terminal 803.

[0108] That is, the last relay terminal 801 refers to the relay terminal connected to the base station. The intermediate relay terminal refers to the relay terminal configured between the last relay terminal 801 and the remote terminal 810. Among the intermediate relay terminals, the first terminal connected to the remote terminal 810 can be further specified as the first relay terminal and recorded.

[0109] For example, a sidelink relay terminal can be distinguished into two relay terminals / functions. For instance, it can be defined as: a sidelink relay terminal that connects to the base station via the Uu interface and to other sidelink relays via the PC5 interface (labeled as the last relay terminal for ease of explanation; this can be replaced by any other name (e.g., PC5-Uu relay terminal, L2 PC5-Uu U2N relay terminal, end relay, top-level relay, parent relay, etc.)) and one or more sidelink relay terminals located between the last relay terminal and the remote terminal (labeled as intermediate relay terminals (type 1) for ease of explanation; this can be replaced by any other name).

[0110] As another example, the functions of relay terminals can be distinguished into three categories. For instance, the sidelink relay terminals can be defined as follows: the sidelink relay terminal connected to the base station via the Uu interface and connected to other sidelink relays via the PC5 interface (the last relay terminal); the sidelink relay terminal directly connected to the remote terminal via the PC5 interface (labeled as the first relay terminal for ease of explanation; this can be replaced by any name such as access relay, relay, underlying relay, sub-relay, etc.); and one or more sidelink relay terminals located between the last relay terminal and the first relay terminal (labeled as intermediate relay terminals (type 2) for ease of explanation; this can be replaced by any other name).

[0111] The last relay terminal can connect to the base station via the Uu interface and to other sidelink relay terminals via the PC5 interface. The last relay terminal can provide connectivity to the network (e.g., the base station) to remote terminals directly or indirectly connected to it. A direct connection between the last relay terminal and a remote terminal means that the remote terminal is directly connected to the aforementioned relay terminal via the PC5 interface.

[0112] For example, it indicates a connection from a remote terminal to the last relay terminal. An indirect connection between the last relay terminal and the remote terminal indicates that the remote terminal is connected to the aforementioned relay terminal through more than one sidelink relay terminal. For example, it indicates a connection from a remote terminal to an intermediate relay terminal to the last relay terminal, or a connection from a remote terminal to the first relay terminal to an intermediate relay terminal to the last relay terminal, etc. In order to provide connectivity to the base station for remote terminals directly / indirectly connected to the last relay terminal, the above-mentioned (multiple) operations can be initiated / triggered / executed when the last relay terminal is within the coverage area of ​​the base station. For example, in cases where the last relay terminal is out of coverage, or Uu RLF, RRC connection fails, etc., the last relay can indicate the above information to the directly / indirectly connected remote terminal and / or intermediate relay terminal and / or first relay terminal.

[0113] The difference between intermediate relay terminals (Type 1) and intermediate relay terminals (Type 2) lies only in whether the sidelink relay terminals are divided into two or three types. They can be directly / indirectly connected to the last relay terminal to provide connectivity to the network (e.g., a base station) to remote terminals directly / indirectly connected to the aforementioned intermediate relay terminals (via the last relay). Hereinafter, for ease of explanation, intermediate relay terminals (Type 1) or intermediate relay terminals (Type 2) will be labeled as intermediate relay terminals. Intermediate relay terminals can operate by consisting of intermediate relay terminals (Type 1). For example, the first relay terminal can also be an intermediate relay terminal. The same values ​​can be set for the corresponding terminal type information.

[0114] Intermediate relay terminals can be operated by consisting of intermediate relay terminals (Type 2). For example, an intermediate relay terminal can be a relay terminal distinct from the first relay terminal. A distinguishing value can be set for the corresponding terminal type information.

[0115] The first relay terminal connects directly to the remote terminal via a PC5 interface to connect to one of the intermediate relay terminals, the last relay terminal, or the base station. For example, the relay terminal or the cell can be selected for connection based on SL-RSRP / SD-RSRP measurements of the aforementioned relay terminal and RSRP measurements of the aforementioned base station cell. When the first relay terminal is directly connected to the base station, it can provide the functionality of the last relay terminal.

[0116] The last relay terminal can connect to (multiple) remote terminals located within the coverage area of ​​the aforementioned terminal's sidelink. For example, it can be connected as remote terminal - last relay terminal - base station. In this case, the last relay terminal can operate in the same manner as existing single-hop relay terminals. Intermediate relay terminals can connect to (multiple) remote terminals located within the coverage area of ​​the aforementioned terminal's sidelink. For example, it can be connected as remote terminal - intermediate relay terminal - last relay terminal - base station. Thus, it can be assumed that all types of sidelink relay terminals are directly connected to remote terminals, allowing the last relay terminal and intermediate relay terminals to provide the first remote terminal function. In this case, the sidelink relay terminal can be processed as two relay terminals / functions (last relay terminal and intermediate relay terminal).

[0117] This configuration allows a sidelink relay terminal to support only one of the following terminal functions at a time: intermediate relay terminal function or last relay terminal function. It also prevents a sidelink relay terminal from simultaneously providing both intermediate and last relay terminal functions. For example, if an intermediate relay terminal detects a PC5-RLF on its PC5 interface with the previous or last relay terminal, the intermediate relay terminal can reconnect to the base station by (disconnecting from the previous or last relay terminal's PC5 connection) and reselecting a cell. In this case, the intermediate relay terminal can operate as the last relay terminal. The base station can instruct the above configuration to allow the intermediate relay terminal to operate as the last relay terminal.

[0118] Furthermore, based on multi-hop sidelink support, a sidelink relay terminal function can be provided simultaneously / at the same time for a terminal operating as a remote terminal. For example, if the aforementioned remote terminal is a terminal capable of implementing intermediate relay terminal function (e.g., an Intermediated relay capable UE), then the aforementioned remote terminal can perform (any of the operations described in this invention) intermediate relay terminal operation. For example, data / traffic of the aforementioned remote terminal can be transmitted to the base station through more than one sidelink relay terminal. When the aforementioned remote terminal operates as a sidelink relay terminal, data / traffic of remote terminals connected to the aforementioned terminal can be transmitted to the base station through more than one sidelink relay terminal.

[0119] For ease of explanation, the following description is based on a 3-hop relay connection of "remote terminal - first relay terminal - intermediate relay terminal - last relay terminal - base station". As mentioned above, the first relay terminal can be an intermediate relay terminal. In this case, the 3-hop relay connection can be established through two different "remote terminal - first intermediate relay terminal - second intermediate relay terminal - last relay terminal - base station" connections. For ease of explanation, the description is based on "remote terminal - first relay terminal - intermediate relay terminal - last relay terminal - base station", but this is only for ease of explanation. Obviously, processing divided into two relay terminals / functions (last relay terminal and intermediate relay terminal) (remote terminal - first intermediate relay terminal - second intermediate relay terminal - last relay terminal - base station) is also included within the scope of this invention.

[0120] For ease of explanation, for two sidelink relay nodes connected via the PC5 interface, the relay node closer to the remote terminal is designated as the lower-level relay terminal, and the relay node closer to the base station is designated as the upper-level relay terminal. This is also for ease of explanation; the term "lower-level relay terminal" can be replaced with any other name such as "downlink relay terminal" or "sub-relay terminal." Similarly, "upper-level relay terminal" can be replaced with any other name such as "uplink relay terminal" or "parent relay terminal."

[0121] For example, among two relay terminals connected via a PC5 interface, the relay terminal with fewer hops connected to the base station (or the relay terminal with more hops connected to the remote terminal) becomes the superior relay terminal. Conversely, among two relay terminals connected via a PC5 interface, the relay terminal with more hops connected to the base station (or the relay terminal with fewer hops connected to the remote terminal) becomes the subordinate relay terminal.

[0122] Figure 9 This is a diagram illustrating the operation of an intermediate relay terminal in one embodiment.

[0123] Reference Figure 9 The connection control method for an intermediate relay terminal providing multi-hop relay operation in a side-link network may include the following steps (S900): receiving system information for multi-hop side-link relay operation.

[0124] For example, an intermediate relay terminal can be configured to perform both relay terminal operations and remote terminal operations simultaneously. The intermediate relay terminal may include relay terminal functionality for relaying data between a remote terminal and a parent terminal. Furthermore, the intermediate relay terminal may include remote terminal functionality for operating as a remote terminal.

[0125] Intermediate relay terminals can operate in the same way as remote terminals to transmit or receive data from higher-level relay terminals. Furthermore, intermediate relay terminals can operate in the same way as relay terminals to transmit or receive data from lower-level relay terminals or remote terminals.

[0126] Intermediate relay terminals can receive sidelink RRC messages from their parent relay terminals. The parent relay terminal is the relay terminal above the intermediate relay terminal, which can be another intermediate relay terminal or the last relay terminal.

[0127] Intermediate relay terminals can receive system information transmitted by the base station. Intermediate relay terminals can receive system information directly from the base station. Alternatively, they can receive system information from the last relay terminal or its parent relay terminal.

[0128] For example, the system information may include at least one of indication information and discovery threshold information indicating whether multi-hop side-link relay operation is supported. The indication information indicating whether multi-hop side-link relay operation is supported indicates whether the base station is capable of supporting the multi-hop side-link relay operation of this disclosure. For example, the indication information may indicate whether the base station has side-link multi-hop relay support functionality. Therefore, the indication information may consist of 1 bit.

[0129] Furthermore, the discovery threshold information may include thresholds for multi-hop side traverse trunk connections. For example, the threshold may represent the RSRP value. The discovery threshold information may represent the SD-RSRP threshold used by the intermediate trunk terminal to evaluate the AS layer conditions for the discovery operation. When performing multi-hop side traverse trunk discovery, the intermediate trunk terminal can evaluate the AS layer conditions by applying the discovery threshold in order to determine whether to pass a discovery request message.

[0130] Additionally, the system information is SIB12, which may contain configuration information for the operational side leglink trunk.

[0131] Intermediate relay terminals can store information contained in the system information. Furthermore, intermediate relay terminals can utilize the configuration information in the system information to configure entities used for relay operations within the terminal.

[0132] The connection control method for intermediate relay terminals may include the following steps (S910): transmitting a discovery message, wherein the discovery message contains at least one of information on whether an RRC connection is established and hop count information on connection to a base station.

[0133] For example, a discovery message can be any of a discovery announcement message, a discovery request (solicitation) message, or a discovery response message. Intermediate relay terminals can use the aforementioned system information to execute the discovery process. The discovery process may include various operations.

[0134] For example, an intermediate relay terminal can transmit a discovery announcement message to indicate whether it supports lateral link relay operations. As another example, an intermediate relay terminal can transmit a discovery request message to perform a connection operation with a parent or child relay terminal to establish a lateral link relay connection. Yet another example, an intermediate relay terminal can transmit a discovery response message to perform a connection operation with the parent or child relay terminal that transmitted the discovery request message.

[0135] The discovery message may include at least one of the following: information regarding whether an RRC connection exists, as described above, and information regarding the number of hops connected to the base station. For example, the RRC connection information may indicate whether the intermediate relay terminal is in an RRC connection state. Alternatively, the RRC connection information may include information indicating whether the intermediate relay terminal is capable of entering an RRC connection state. The connection hop count information may include a count value representing the number of hops the intermediate relay terminal has connected to the base station. Furthermore, the discovery message may also include a maximum hop limit (Hop limit) that the intermediate relay terminal can connect to the base station.

[0136] In addition, it can be determined whether to transmit a discovery message based on the signal strength information of the discovery request message received from the child relay node and the discovery threshold information contained in the system information.

[0137] For example, an intermediate relay terminal can receive a discovery request message from a sub-relay terminal. The intermediate relay terminal can determine whether to transmit the discovery message based on a comparison between the signal strength information of the received discovery request message and the discovery threshold information. For example, if the received signal strength of the discovery request message exceeds the discovery threshold (or is above the discovery threshold), it can be determined that the discovery message should be transmitted.

[0138] The discovery message can be a discovery request message or a discovery response message.

[0139] For example, if an intermediate relay terminal receives a discovery request message from a child relay terminal with a signal strength exceeding the discovery threshold, the intermediate relay terminal can forward the discovery request message to the parent relay terminal. This discovery request message may include indications of whether an RRC connection is established, hop count information, hop count limit information, etc., as described above.

[0140] In another example, if an intermediate relay terminal already has a parent relay terminal (e.g., the last relay terminal) and a link based on the PC5 interface, and the signal strength of the discovery request message exceeds the discovery threshold, a discovery response message can be transmitted to the child relay terminal.

[0141] Thus, the remote terminal can connect sequentially to the sub-relay terminal (the first relay terminal), the intermediate relay terminal, and the last relay terminal to establish a multi-hop side-link relay connection.

[0142] Figure 10 This is a diagram illustrating the operation of the last relay terminal in one embodiment.

[0143] Reference Figure 10 The connection control method for the last relay terminal providing multi-hop relay operation in a sidelink network may include the following steps (S1000): receiving system information for multi-hop sidelink relay operation from the base station.

[0144] The final relay terminal can receive system information transmitted by the base station. System information can be received via SIB12.

[0145] For example, the system information may include at least one of indication information and discovery threshold information indicating whether multi-hop side-link relay operation is supported. The indication information indicating whether multi-hop side-link relay operation is supported indicates whether the base station is capable of supporting the multi-hop side-link relay operation of this disclosure. For example, the indication information may indicate whether the base station has side-link multi-hop relay support functionality. Therefore, the indication information may consist of 1 bit.

[0146] Furthermore, the discovery threshold information may include thresholds for multi-hop side traverse trunk connections. For example, the threshold may represent the RSRP value. The discovery threshold information may represent the SD-RSRP threshold used by an intermediate trunk terminal, the last trunk terminal, or the first trunk terminal to evaluate the AS layer conditions for the discovery operation. When performing multi-hop side traverse trunk discovery, the last trunk terminal may evaluate the AS layer conditions by applying the discovery threshold in order to determine whether to transmit a response message regarding the discovery request message.

[0147] The last relay terminal can store information contained in the system information. Furthermore, the last relay terminal can utilize the configuration information in the system information to configure entities used for relay operations within the terminal.

[0148] Finally, the connection control method of the relay terminal may also include the following step (S1010): receiving a discovery request (solicitation) message from the sub-relay terminal.

[0149] For example, the last relay terminal can receive discovery request messages transmitted by lower-level sub-relay terminals. Here, a sub-relay terminal can refer to an intermediate relay terminal whose PC5 interface link is not connected to the last relay terminal.

[0150] The connection control method for the last relay terminal may include the following steps (S1020): determining whether to transmit a discovery response message based on the discovery request message and system information.

[0151] For example, the last relay terminal can initiate a connection operation with a sub-relay terminal by transmitting a discovery response message, whereby the sub-relay terminal transmits a discovery request message. To this end, the last relay terminal can determine whether to transmit a discovery response message in response to the discovery request message.

[0152] For example, the decision to transmit a discovery response message can be made based on the signal strength information of the discovery request message and the discovery threshold information included in the system information. For instance, if the signal strength exceeds the discovery threshold, the last relay terminal can determine to transmit a discovery response message to the sub-relay terminal. That is, if the received discovery request message shows a reception strength above the discovery threshold, it can be determined to transmit a discovery response message. Here, the reception strength can be the RSRP value.

[0153] The discovery request message or discovery response message may contain at least one of the following: information on whether an RRC connection exists and hop count information for connection to the base station. For example, the RRC connection information may indicate whether the last relay terminal or intermediate relay terminal is in an RRC connection state. Alternatively, the RRC connection information may include information indicating whether the intermediate relay terminal or last relay terminal is capable of entering an RRC connection state. The hop count information for connection to the base station may include a count value representing the number of hops the intermediate relay terminal or last relay terminal has connected to the base station. Furthermore, the discovery request message or discovery response message may also include a maximum hop limit (Hop limit) that the intermediate relay terminal or last relay terminal can connect to the base station.

[0154] Finally, the connection control method of the relay terminal may also include the following step (S1030): transmitting a discovery response message to the sub-relay terminal.

[0155] Finally, the relay terminal can transmit a discovery response message to the sub-relay terminal based on the aforementioned determination result of whether to transmit a discovery response message.

[0156] Thus, the remote terminal can connect sequentially to the sub-relay terminal (the first relay terminal), the intermediate relay terminal, and the last relay terminal to establish a multi-hop side-link relay connection.

[0157] The operations described above primarily focus on the discovery process. However, as shown below, the aforementioned operations and information elements apply not only to the discovery process but also to the selection / reselection of cells (relays).

[0158] The following describes further embodiments of the sidelink relay connection operation that can be performed through the aforementioned terminal.

[0159] Select / Reselect the discovery and relay terminal among sidelink relay terminals.

[0160] To support multi-hop sidelink relay, similar to existing sidelink relay terminals, the last relay terminal, intermediate relays, and the first relay terminal can all serve as a single terminal to support core network (e.g., 5G system) access. However, existing sidelink relay terminals only support discovery by remote terminals. Therefore, to support multi-hop sidelink relay, a scheme for providing discovery services between relay terminals is needed.

[0161] For example, a sidelink relay terminal provides discovery parameters for the aforementioned relay terminal via a Relay Service Code (RSC), or via indication information associated with the Relay Service Code, or via any parameters included in the discovery message (e.g., Type of Discovery Message, Discoverer Info, RSC, indication information connected to the RSC, Source Layer-2 ID, Destination Layer-2 ID, hop count, cell ID, any newly defined parameters, etc.). These parameters indicate whether the aforementioned sidelink relay provides the last relay terminal function / service and / or whether it provides the intermediate relay terminal function / service (or, information indicating whether the last relay terminal function / service, and / or whether it provides the intermediate relay terminal function / service, and / or whether it provides the first relay terminal function / service).

[0162] For example, a relay service code can be used to indicate the functionality / service support of the last relay terminal for a normal service. A relay service code can be used to indicate the functionality / service support of an intermediate relay terminal for a normal service. A relay service code can be used to indicate the functionality / service support of the first relay terminal for a normal service. A relay service code can be used to indicate the functionality / service support of a multi-hop side link relay terminal for a normal service. A relay service code can be used to indicate the connectivity functionality / service support of an intermediate relay terminal for a normal service.

[0163] As another example, a trunk service code can be used to indicate support for the last trunk terminal's functionality / service for emergency (or emergency and normal service). A trunk service code can be used to indicate support for the functionality / service of an intermediate trunk terminal for emergency (or emergency and normal service). A trunk service code can be used to indicate support for the functionality / service of the first trunk terminal for emergency (or emergency and normal service). A trunk service code can be used to indicate support for the functionality / service of a multi-hop side walkway trunk terminal for emergency (or emergency and normal service). A trunk service code can be used to support connectivity functionality / service for intermediate trunk terminals for emergency (or emergency and normal service).

[0164] For another example, for each (arbitrary) RSC, information indicating whether the aforementioned sideline trunk provides the last trunk terminal function / service and / or whether it provides intermediate trunk terminal function / service can be provided as the discovery parameters for the aforementioned trunk terminal. For each (arbitrary) RSC, information indicating whether the aforementioned sideline trunk provides the last trunk terminal function / service and / or whether it provides intermediate trunk terminal function / service and / or information indicating whether it provides the first trunk terminal function / service can be provided as the discovery parameters for the aforementioned trunk terminal. For each (arbitrary) RSC, information indicating that the aforementioned sideline trunk supports multi-hop sideline trunk terminal function / service can be provided as the discovery parameters for the aforementioned trunk terminal. For each (arbitrary) RSC, information supporting connectivity functions / services for intermediate trunk terminals can be provided as the discovery parameters for the aforementioned trunk terminal.

[0165] As another example, the discovery parameters for the aforementioned relay terminal can be provided by any field included in the discovery message (e.g., User InfoID or a new field), (in the manner associated with the aforementioned RSC, or independently of the RSC, for the overall RSC), which indicates whether the aforementioned side link relay provides the last relay terminal function / service, and / or whether it provides the intermediate relay terminal function / service.

[0166] Discovery parameters for the aforementioned relay terminal may be provided through any field included in the discovery message (e.g., User Info ID or a new field), (in association with the aforementioned RSC, or independently of the RSC for the overall RSC), containing information indicating whether the aforementioned sideline relay provides the last relay terminal function / service and / or whether it provides intermediate relay terminal function / service, and / or information indicating whether it provides the first relay terminal function / service. Discovery parameters for the aforementioned relay terminal may also be provided through any field included in the discovery message (e.g., User Info ID or a new field), (in association with the aforementioned RSC, or independently of the RSC for the overall RSC), containing information indicating that the aforementioned sideline relay supports multi-hop sideline relay terminal function / service. The discovery parameters for the aforementioned relay terminal may be provided by any field included in the discovery message (e.g., User Info ID or a new field), (in the manner associated with the aforementioned RSC, or independently of the RSC, for the overall RSC), which indicates that the aforementioned side link relay supports connectivity functions / services for the intermediate relay terminal.

[0167] As another example, the last relay terminal should be able to establish a wireless connection with the base station within its coverage area. Otherwise, it will be difficult for other sidelink relay terminals to provide connectivity to the base station. The last relay terminal will only determine whether it can transmit any discovery message, or send / receive discovery messages, if the aforementioned terminal is within the base station's coverage area.

[0168] The base station can indicate to the aforementioned terminals, either through system information broadcasts or through dedicated RRC messages, the thresholds used to confirm whether the last relay terminal can transmit arbitrary discovery messages (e.g., maximum Uu RSRP threshold, minimum Uu RSRP threshold). The last relay terminal can determine whether it can transmit arbitrary discovery messages and send / receive discovery messages based on whether the aforementioned terminals meet the threshold conditions in the cell (or PCell) they are camped in (e.g., the maximum Uu RSRP threshold is not configured; or in the cell (or PCell) they are camped in, the RSRP measurement value is lower than the maximum Uu RSRP threshold by a specific compensation value (hystMaxRelay); and, the minimum Uu RSRP threshold is not configured; or in the cell (or PCell) they are camped in, the RSRP measurement value is higher than the minimum Uu RSRP threshold by a specific compensation value (hystMinRelay)).

[0169] The aforementioned threshold parameters / information elements can reuse parameters / information elements provided for U2N relay terminals in existing technologies. However, to distinguish whether a relay terminal provides functions different from those of existing U2N relay terminals, the base station can include any new parameter / information elements in the terminal configuration information. These parameter / information elements can be explicit indication information indicating the type of the last relay terminal. They can also be explicit indication information indicating connectivity support to any side link relay terminal. To indicate connectivity support to any side link relay terminal, it can be implicitly indicated through the required information. Alternatively, the threshold parameters / information elements can be defined as new parameter / information elements different from those provided for U2N relay terminals in existing technologies. Thus, the last relay terminal can determine to transmit discovery messages to other side link relay terminals.

[0170] As another example, in the prior art, if the maximum Uu RSRP threshold and the minimum Uu RSRP threshold are not configured, the U2N relay terminal, considering that the threshold conditions are met, determines to transmit an arbitrary discovery message to perform discovery. To support multi-hop side-link relay, the ability to connect to a base station becomes an important consideration when selecting a relay. Therefore, the thresholds (e.g., the maximum Uu RSRP threshold and the minimum Uu RSRP threshold) used to determine whether the last relay terminal can transmit an arbitrary discovery message can be pre-configured in the terminal. For example, if the base station serving the cell (or PCell) where the terminal is camped does not broadcast the aforementioned information via system information or indicate the aforementioned information to the terminal via a dedicated RRC message, the terminal can also determine to transmit a discovery message by using the aforementioned thresholds.

[0171] As another example, the last relay terminal may include the information required for the intermediate relay terminal (and / or the first relay terminal and / or the remote terminal) to select / reselect the last relay terminal in a discovery message (e.g., one or more messages such as an announcement message, a solicitation message, or a response message to a solicitation message) for sending / receiving.

[0172] The last relay terminal may send / receive information within the base station's coverage area that indicates the aforementioned sidelink relay is in a state capable of providing the last relay terminal's functions / services, contained in discovery messages (e.g., one or more messages such as announcement messages, solicitation messages, or response messages to solicitation messages).

[0173] The last relay terminal may provide the information indicating that the aforementioned sidelink relay is within the coverage area of ​​the base station as the discovery parameters of the relay terminal through the Relay Service Code (RSC), or through indication information associated with the Relay Service Code, or through any parameters included in the discovery message.

[0174] The last relay terminal can provide information as the discovery parameters of the relay terminal, which indicates whether the aforementioned sidelink relay is within the coverage area of ​​the base station and is providing the last relay terminal function / service, through the Relay Service Code (RSC), or through indication information associated with the Relay Service Code, or through any parameters included in the discovery message.

[0175] The last relay terminal can provide discovery parameters for the relay terminal by means of the Relay Service Code (RSC), or by indication information associated with the Relay Service Code, or by any parameters included in the discovery message, which indicate that the aforementioned sidelink relay is in a state of connection with the base station via the Uu interface (e.g., RRC connection) or is in a connectable state. For example, the above information can be included and transmitted within the RRC container included in the discovery announcement message.

[0176] The last relay terminal can set the hop count information for the connection between the aforementioned sidelink relay and the base station to 0 (or a specific value: 1 as the hop count for the connection with the base station) via the Relay Service Code (RSC), or by indication information associated with the Relay Service Code, or by any parameter included in the discovery message. The last relay terminal can use this to indicate that it is in a state where it can connect to the base station.

[0177] The last relay terminal can provide the cell identification information (one of any cell identification information such as NR CGI, PCI, etc.) of the sidelink relay (hosted / connected / connectable / located within the coverage area) as the discovery parameters of the relay terminal via the Relay Service Code (RSC), or by indication information associated with the Relay Service Code, or by any parameters included in the discovery message. This implicitly indicates that the sidelink relay is within the coverage area. Alternatively, relay terminals located in the same cell can be preferentially selected / reselected based on the cell identification information. For example, other relay terminals (or remote terminals) can preferentially select / reselect the last relay terminal located in the same cell as the aforementioned relay terminal based on the cell identification information.

[0178] The last relay terminal can provide the Uu RSRP measurement value of the aforementioned sidelink relay connection / connectable / covered cell / base station as the discovery parameter of the aforementioned relay terminal via the Relay Service Code (RSC), or via indication information associated with the Relay Service Code, or via any parameters included in the discovery message. This information can represent the measurement value itself, or it can represent information encoding the measurement value as an nth order (n is a natural number greater than 1) (e.g., good / average / poor). This information can be used by intermediate relay terminals or remote terminals to select the aforementioned relay terminal.

[0179] An intermediate relay terminal (e.g., a UE capable of intermediate relay UE) can select / reselect the last relay terminal or another intermediate relay terminal under the following conditions.

[0180] For example, when the intermediate relay terminal does not have a serving cell; or

[0181] In the cell (or PCell) where the terminal is camped, when the RSRP measurement is lower than a specific Uu RSRP threshold (e.g., maximum / high Uu RSRP threshold, thrsh_Max / High) pre-configured / indicated in the intermediate relay terminal (or when it is lower than a specific compensation value (hystMax / High) compared to the specific Uu RSRP threshold):

[0182] If the intermediate relay terminal does not have the last selected relay terminal or other intermediate relay terminals; or

[0183] If the intermediate relay terminal has the last selected relay terminal or other intermediate relay terminals, but the SL-RSRP / SD-RSRP of the currently selected relay terminal is less than the above threshold (e.g., sl-RSRP-Thresh / sd-RSRP-Thresh); or

[0184] If an intermediate relay terminal has the last selected relay terminal or other intermediate relay terminals, but the upper layer indicates that the currently selected relay terminal should not be used; or

[0185] If the intermediate relay terminal has the last selected relay terminal or other intermediate relay terminals, but the upper layer requests to terminate the aforementioned PC5-RRC connection; or

[0186] If the intermediate relay terminal has the last selected relay terminal or other intermediate relay terminals, but a sidelink radio link failure is detected on the aforementioned PC5-RRC connection; or

[0187] Intermediate relay terminals can perform a sidelink discovery procedure to retrieve candidate last relay terminals or other intermediate relay terminals. Intermediate relay terminals may consider sidelink relay terminals whose SD-RSRP exceeds a specific threshold (e.g., sl-RSRP-Thresh / sd-RSRP-Thresh) (or exceeds a specific compensation value (sl-HystMin) compared to the specific threshold) as candidate last relay terminals (or candidate intermediate relay terminals). If an intermediate relay terminal detects any suitable last relay terminal (or intermediate relay terminal), it can select one of the available suitable last relay terminals (or intermediate relay terminals). To select a suitable last relay terminal (or intermediate relay terminal), the intermediate relay terminal may verify, during the discovery procedure, that the PLMN has been authorized to connect to the aforementioned last relay terminal (or intermediate relay terminal) from the information obtained from the last relay terminal (or intermediate relay terminal).

[0188] As another example, when connecting a remote terminal to a base station via a multi-hop sidelink relay, if the sidelink relay terminal included in the path between the remote terminal and the base station is within the base station's coverage area, it is preferable for the sidelink relay terminal to connect via a relay terminal located within the same cell's coverage area. Otherwise, inconsistencies in parameters may occur during any sidelink relay operation, including resource allocation. To avoid the above problems, the operation can be performed as follows.

[0189] When a remote terminal is within the coverage area of ​​a base station (e.g., when the RSRP measurement value is greater than a specific Uu RSRP threshold pre-configured / specified / indicated in the remote terminal), it can select / reselect the last relay terminal camped in the same cell as the aforementioned camped cell (or use the same cell as the PCell to implement the RRC connection). The remote terminal may prioritize the aforementioned cell (or the frequency of the aforementioned cell) when selecting / reselecting a relay terminal. If the remote terminal is outside the coverage area of ​​the base station, the remote terminal may disregard cell information and (according to existing methods) select / reselect a relay terminal.

[0190] When an intermediate relay terminal is within the coverage area of ​​a base station (e.g., when the RSRP measurement value is greater than a specific Uu RSRP threshold pre-configured / specified / indicated in the remote terminal), it can select / reselect the last relay terminal camped in the same cell as the aforementioned camped cell (or use the same cell as the PCell to implement the RRC connection). The remote terminal can prioritize the aforementioned cell (or the frequency of the aforementioned cell) when selecting / reselecting a relay terminal. If the intermediate relay terminal is outside the coverage area of ​​the base station, the remote terminal can disregard cell information and (according to existing methods) select / reselect a relay terminal.

[0191] As another example, even if an intermediate relay terminal is outside the coverage area of ​​the base station, a wireless connection with the base station should still be established through the last relay terminal or another intermediate relay terminal. For example, as described in the foregoing embodiments, when an intermediate relay terminal does not have a serving cell, the last relay terminal or another intermediate relay terminal can be selected / reselected according to the aforementioned procedure.

[0192] As another example, when an intermediate relay terminal is within the coverage area of ​​a base station, a wireless connection with the base station should also be established through the last relay terminal. For instance, as described in the foregoing embodiments, in the cell (or PCell) where the terminal is camped, when the RSRP measurement value is lower than a specific Uu RSRP threshold (e.g., maximum / high Uu RSRP threshold, thrsh_Max / High) pre-configured / configured / indicated in the intermediate relay terminal (or when it is lower than a specific compensation value (hystMax / High) compared to the specific Uu RSRP threshold), the last relay terminal or another intermediate relay terminal can be selected / reselected according to the aforementioned procedure.

[0193] The base station can indicate to the aforementioned terminals via system information broadcasts or dedicated RRC messages the threshold used to confirm whether an intermediate relay terminal can transmit an arbitrary discovery message, and / or the threshold used to select / reselect an intermediate relay terminal. These parameters can be any information included in the foregoing embodiments. For example, they can include one or more of the SD-RSRP threshold and compensation values ​​(hystMax / hystMin). Whether to transmit an arbitrary discovery message can be determined using these parameters. When an intermediate relay terminal receives a discovery request (solicitation) message from a first relay terminal, if the SD-RSRP is higher than the compensation value compared to the threshold, the intermediate relay terminal can determine to transmit a discovery response message to the first relay terminal. Alternatively, when an intermediate relay terminal receives a discovery request (solicitation) message from a first relay terminal, if the SD-RSRP is higher than the compensation value compared to the threshold, the intermediate relay terminal can determine to transmit a discovery request (solicitation) message to the last relay terminal or other intermediate relay terminals. The aforementioned threshold parameters / information elements can be indicated as parameters that differ from those provided by existing technologies for selecting / reselecting U2N relays.

[0194] As another example, the base station can instruct the aforementioned terminal, via system information broadcast or dedicated RRC messages, on the information required for selecting / reselecting the last relay terminal or other intermediate relay terminals. This information may include one or more of the following: the maximum allowed hop count for the intermediate relay terminal; information indicating a preference for selecting / reselecting a cell identical to the cell where the last relay terminal is camped / connected; information indicating a preference for selecting / reselecting hop counts (up to the base station); and information indicating a preference for selecting / reselecting lateral link determinations (e.g., SL-RSRP / SD-RSRP determinations) for the aforementioned relay terminal. For example, if the maximum allowed hop count for the intermediate relay terminal is indicated, through relay terminal discovery, even if the intermediate relay terminal (meeting a specific threshold) is a lateral link relay terminal, if the connection hop count between the aforementioned relay terminal and the base station exceeds the maximum hop count configured / indicated in the intermediate relay terminal, the aforementioned lateral link relay terminal may not be considered a suitable relay terminal (it can be excluded). Alternatively, the aforementioned lateral link relay terminal may not be considered a candidate relay terminal (it can be excluded). As another example, if the intermediate relay terminal is configured / indicated to use the information it prioritizes when selecting a relay (e.g., cell, hop count, side link measurement), the intermediate relay terminal can prioritize the above information to select / reselect the last relay terminal or another relay terminal.

[0195] For intermediate relay terminals or remote terminals, relay selection that takes hop count into account is supported.

[0196] Intermediate relay terminals may include the information required for other intermediate relay terminals (and / or the first relay terminal, and / or the remote terminal) to select / reselect intermediate relay terminals in discovery messages (e.g., announcement messages or solicitation messages, or one or more messages in response to solicitation messages) for sending / receiving.

[0197] Intermediate relay terminals can provide information indicating that the aforementioned sidelink relay is within the coverage area of ​​the base station as discovery parameters for the relay terminal, either through the Relay Service Code (RSC), or through indication information associated with the Relay Service Code, or through any parameters included in the discovery message.

[0198] Intermediate relay terminals can provide information as discovery parameters for the aforementioned relay terminals, which indicates whether the aforementioned side link relay is directly / indirectly connected to the last relay and is in a state capable of providing intermediate relay terminal functions / services, through the Relay Service Code (RSC), or through indication information associated with the Relay Service Code, or through any parameters included in the discovery message.

[0199] Intermediate relay terminals can provide information as discovery parameters to indicate that the aforementioned side link relay is in an RRC connected state or a connectable state due to a direct / indirect connection with the last relay, through the Relay Service Code (RSC), or through indication information associated with the Relay Service Code, or through any parameters included in the discovery message. For example, the aforementioned information can be included and transmitted within the RRC container contained in the discovery announcement message.

[0200] Intermediate relay terminals may provide the hop count information of the aforementioned sidelink relay connection to the base station (or the hop count information of the last relay connection, or a value minus 1 from the hop count information of the connection to the base station) as the discovery parameters of the aforementioned relay terminal through the Relay Service Code (RSC), or through indication information associated with the Relay Service Code, or through any parameter included in the discovery message.

[0201] Intermediate relay terminals can provide the identification information (one of any cell identification information such as NR CGI, PCI, etc.) of the cells where the aforementioned sidelink relay is camped / connected / connectable / located within the coverage area, or any cell identification information (e.g., NR CGI, PCI) that meets a specific threshold, as discovery parameters for the aforementioned relay terminal, through the Relay Service Code (RSC), or through indication information associated with the Relay Service Code, or through any parameters included in the discovery message. For example, other intermediate relay terminals (or remote terminals) can preferentially select / reselect intermediate relay terminals located in the same cell as the aforementioned relay terminal based on the aforementioned cell identification information.

[0202] Intermediate relay terminals can include the PC5 RSRP measurement value of the relay terminal connected to / connectable to the aforementioned side link relay via the Relay Service Code (RSC), or via indication information associated with the Relay Service Code, or via any parameters included in the discovery message. This information can represent the measurement value itself, or it can represent information encoding the measurement value as an nth order (n is a natural number greater than 1) (e.g., good / average / poor). This information can be used by the intermediate relay terminal or the remote terminal to select the aforementioned relay terminal.

[0203] Intermediate relay terminals can provide path information for the connection between the aforementioned sidelink relay and the base station as discovery parameters via a Relay Service Code (RSC), indication information associated with the RSC, or any parameters included in the discovery message. This information can represent a set of sidelink relay terminals providing the connection / connectivity between the intermediate relay terminal and the base station. For example, if the intermediate relay terminal is connected to the last relay terminal, the last relay terminal information may be included. If the intermediate relay terminal is connected to the last relay terminal through another intermediate relay terminal, information about other intermediate relay terminals and the last relay terminal may be included. The relay terminal information can use one or more of the relay terminal's identification information (e.g., LocalUE ID, L2 target ID, L2 source ID). This information can be used to enable intermediate relay terminals or remote terminals to select / reselect the aforementioned relay terminal.

[0204] RRC Connection Management and Control Methods

[0205] Before transmitting user plane data, the L2 remote terminal should establish a PDU session and DRB. In existing single-hop-based sidelink relay technology, the process for establishing a remote terminal connection first involves a discovery process between the remote terminal and the relay terminal, and then a PC5 connection (or PC5-RRC connection) establishment using the NR sidelink PC5 unicast link establishment process. Afterward, the remote terminal performs the RRC establishment process with the base station through the relay terminal.

[0206] To support multi-hop-based sidelink relay, simply performing the discovery process between the remote terminal and the relay terminal and establishing a PC5 connection may not be sufficient to establish a base station connection. Further steps are required to support this.

[0207] For example, the discovery process between the remote terminal and the first relay terminal, the discovery between the first relay terminal and the intermediate relay terminals, and the discovery between the intermediate relay terminals and the last relay terminal are performed sequentially. The remote terminal can also perform the RRC establishment process with the base station through multiple relay terminals.

[0208] A remote terminal can establish a PC5 connection by discovering any relay terminal. For example, the remote terminal can perform a discovery procedure. The remote terminal can select the first relay terminal. The remote terminal and the first relay terminal can establish a PC5-RRC connection using the NR-side crosslink PC5 unicast link establishment procedure.

[0209] If the first relay terminal cannot provide connectivity to the base station via the Uu interface (e.g., if Uu-RSRP is less than a certain threshold), the first relay terminal may perform a discovery procedure to retrieve another relay terminal. For example, the first relay terminal may perform a discovery procedure. The first relay terminal may select an intermediate relay terminal. The first relay terminal and the intermediate relay terminal establish a PC5-RRC connection using the NR-side crosslink PC5 unicast link establishment procedure.

[0210] If the aforementioned intermediate relay terminal cannot provide connectivity to the base station via the Uu interface (e.g., if Uu-RSRP is less than a certain threshold), the first relay terminal may perform a discovery procedure to retrieve another relay terminal. For example, the intermediate relay terminal may perform a discovery procedure. The intermediate relay terminal may select the last relay terminal. The intermediate relay terminal and the last relay terminal establish a PC5-RRC connection using the NR-side crosslink PC5 unicast link establishment procedure.

[0211] If an intermediate relay terminal is connected to the last relay terminal (e.g., establishing a PC5-RRC connection), the intermediate relay terminal can direct it to the first relay terminal. The first relay terminal can then direct it to the remote terminal.

[0212] A remote terminal can establish an RRC connection with a base station by transmitting RRC setup / establishment request messages (e.g., RRCSetupRequest) through multiple sidelink relay terminals. These messages can be transmitted using PC5 relay RLC channel configurations specified between the remote terminal and the first relay terminal, between the first relay terminal and intermediate relay terminals, and between intermediate relay terminals and the last relay terminal.

[0213] When the first relay terminal receives a message on the specified PC5 relay RLC channel, if the first relay terminal is not in an RRC connection state, it can perform its own RRC connection setup / establishment process. The first relay terminal can establish an RRC connection with the base station by transmitting RRC setup / establishment request messages (e.g., RRCSetupRequest) through multiple sidelink relay terminals. These messages can be transmitted using the PC5 relay RLC channel configuration specified between the first relay terminal and intermediate relay terminals, or between intermediate relay terminals and the last relay terminal. The base station can transmit RRC establishment messages (e.g., RRCSetup) to the first relay terminal. These messages can also be transmitted using the PC5 relay RLC channel configuration specified between the first relay terminal and intermediate relay terminals, or between intermediate relay terminals and the last relay terminal. The first relay terminal can request support for the dedicated configurations required by the remote terminal through sidelink terminal information messages.

[0214] When an intermediate relay terminal receives a message on the specified PC5 relay RLC channel, if the intermediate relay terminal is not in an RRC connection state, it can perform its own RRC connection setup / establishment process. The intermediate relay terminal can transmit an RRC setup / establishment request message (e.g., RRCSetupRequest) through a sidelink relay terminal to establish an RRC connection with the base station. This message can be transmitted using the PC5 relay RLC channel configuration specified between the intermediate relay terminal and the last relay terminal. The base station can transmit an RRC establishment message (e.g., RRCSetup) to the intermediate relay terminal. This message can also be transmitted using the PC5 relay RLC channel configuration specified between the intermediate relay terminal and the last relay terminal. The intermediate relay terminal can request support for the special configuration required by the remote terminal through a sidelink terminal information message.

[0215] When the last relay terminal receives a message on the designated PC5 relay RLC channel, if the last relay terminal is not in an RRC connection state, it can perform its own Uu RRC connection setup / establishment process. The last relay terminal can request support for the special configurations required by the remote terminal through the sidelink terminal information message.

[0216] After the RRC connection establishment process and transmission of the crosslink terminal information message at the last relay terminal, the base station can configure an SRB0 for relaying the Uu relay RLC channel to the last relay terminal. The base station can respond to the remote terminal with an RRC establishment message (e.g., RRCSetup). The aforementioned RRC message can be transmitted from the base station to the last relay terminal using an SRB0 for relaying the Uu relay RLC channel. The aforementioned RRC message can be transmitted from the last relay terminal to an intermediate relay terminal using a designated PC5 relay RLC channel. The aforementioned RRC message can be transmitted from an intermediate relay terminal to the first relay terminal using a designated PC5 relay RLC channel. The aforementioned RRC message can be transmitted from the first relay terminal to the remote terminal using a designated PC5 relay RLC channel.

[0217] The base station can establish a relay channel with the last relay terminal via Uu. The base station can transmit an RRC reconstruction message to the last relay terminal. The base station can transmit an RRC reconstruction message to intermediate relay terminals. The base station can transmit an RRC reconstruction message to the first relay terminal. The base station can transmit an RRC reconstruction message to a remote terminal. Depending on the base station configuration, the last relay terminal and intermediate relay terminals can establish a PC5 RLC channel for SRB1 relay.

[0218] In another example, the discovery process between the last relay terminal and the intermediate relay terminal, the discovery between the intermediate relay terminal and the first relay terminal, and the discovery between the first relay terminal and the remote terminal are performed sequentially. The remote terminal can perform the RRC establishment process with the base station through multiple relay terminals.

[0219] For example, the last relay terminal and intermediate relay terminals can perform the discovery process. For instance, if the last relay terminal receives a paging message for a remote terminal through a base station, then the last relay terminal can perform the discovery process. The last relay terminal can select an intermediate relay terminal. Alternatively, the last relay terminal can select an intermediate relay terminal.

[0220] The last relay terminal and intermediate relay terminals can establish a PC5-RRC connection using the NR sidelink PC5 unicast link establishment procedure. (Optionally) The intermediate relay terminal can perform the RRC establishment procedure with the base station through the last relay terminal. The intermediate relay terminal can transmit an RRC setup / establishment request message (e.g., RRCSetupRequest) through the sidelink relay terminal to establish an RRC connection with the base station. This message can be transmitted using the PC5 relay RLC channel configuration specified between the intermediate and last relay terminals. The base station can transmit an RRC establishment message (e.g., RRCSetup) to the intermediate relay terminal. This message can be transmitted using the PC5 relay RLC channel configuration specified between the last and intermediate relay terminals. The last relay terminal (or intermediate relay terminal) can request support for the special configuration required by the aforementioned remote terminal through a sidelink terminal information message. The last relay terminal can transmit the paging message received from the base station to the intermediate relay terminal through a sidelink RRC message. Alternatively, the base station can retransmit / transmit the paging message to the intermediate relay terminal through the last relay terminal. As another method, the intermediate relay terminal performs the steps of the RRC establishment process with the base station through the last relay terminal, which can be performed after the first relay terminal discovers the remote terminal to establish a PC5 connection.

[0221] The intermediate relay terminal and the first relay terminal can perform the discovery process. The intermediate relay terminal can select the first relay terminal. Alternatively, the first relay terminal can select the intermediate relay terminal.

[0222] Intermediate relay terminals and the first relay terminal can establish a PC5-RRC connection using the NR sidelink PC5 unicast link establishment procedure. (Optionally) the first relay terminal can perform the RRC establishment procedure with the base station through the intermediate relay terminal (or multiple multi-hop sidelink relays including the intermediate relay terminal). The first relay terminal can establish an RRC connection with the base station by transmitting an RRC setup / establishment request message (e.g., RRCSetupRequest) through the sidelink relay terminal.

[0223] The above messages can be transmitted using the PC5 Relay RLC channel configuration specified between the first relay terminal and the intermediate relay terminal, and the PC5 Relay RLC channel configuration specified between the intermediate relay terminal and the last relay terminal. The base station can transmit an RRC establishment message (e.g., RRCSetup) to the intermediate relay terminal. The above messages can also be transmitted using the PC5 Relay RLC channel configuration specified between the last relay terminal and the intermediate relay terminal, and the PC5 Relay RLC channel configuration specified between the intermediate relay terminal and the first relay terminal. The intermediate relay terminal can request support for the dedicated configuration required by the aforementioned remote terminal via a sidelink terminal information message. The intermediate relay terminal can transmit the paging message received from the base station (or from the last relay terminal) to the first relay terminal via a sidelink RRC message. Alternatively, the base station can retransmit / transmit the paging message to the first relay terminal via both the last relay terminal and the intermediate relay terminals.

[0224] As another method, the first relay terminal performs the steps of the RRC establishment process with the base station through the intermediate relay terminal, which can be performed after the first relay terminal discovers the remote terminal to establish a PC5 connection.

[0225] The first relay terminal and the remote terminal can perform the discovery process. The first relay terminal can select the remote terminal. Alternatively, the remote terminal can select the first relay terminal.

[0226] The first relay terminal and the remote terminal can establish a PC5-RRC connection using the NR-side crosslink PC5 unicast link establishment procedure. The remote relay terminal can perform the RRC establishment procedure with the base station through the first relay terminal (or multiple multi-hop crosslink relays including the first relay terminal).

[0227] A remote terminal can establish an RRC connection with the base station by transmitting an RRC setup / establishment request message (e.g., RRCSetupRequest) through a sidelink relay terminal. This message can be transmitted using a PC5 relay RLC channel configuration specified between the remote terminal and the first relay terminal, between the first relay terminal and intermediate relay terminals, or between an intermediate relay terminal and the last relay terminal. The base station can transmit an RRC establishment message (e.g., RRCSetup) to the first relay terminal.

[0228] The aforementioned messages can be transmitted via the PC5 relay RLC channel configuration specified between the last relay terminal and intermediate relay terminals, the PC5 relay RLC channel configuration specified between the intermediate relay terminal and the first relay terminal, and the PC5 relay RLC channel configuration specified between the first relay terminal and the remote terminal. The first relay terminal can request support for the specific configuration required by the remote terminal via a sidelink terminal information message. The first relay terminal can transmit the paging message received from the base station (or from the intermediate relay terminal) to the remote terminal via a sidelink RRC message. Alternatively, the base station can retransmit / transmit the paging message to the remote terminal via the last relay terminal, intermediate relay terminals, and the first relay terminal. As another method, the paging message can be executed before the remote terminal performs RRC connection setup / establishment with the base station via the sidelink relay terminal.

[0229] As another method, the first relay terminal performs the steps of the RRC establishment process with the base station through an intermediate relay terminal, which can be performed after the first relay terminal discovers the remote terminal to establish a PC5 connection. For example, it can be performed when the remote terminal transmits an RRC setup / establishment request message (e.g., RRCSetupRequest) to the first relay terminal.

[0230] In another example, for a remote terminal to support connectivity to a base station via a multi-hop sidelink relay terminal, it needs to first confirm whether connectivity with the base station is possible. Therefore, a multi-hop sidelink relay connection can only be established if the discovery of sidelink relay terminals within the base station's coverage area and / or the establishment of a PC5 connection are possible.

[0231] An intermediate relay terminal will only select / reselect the last relay (and / or other intermediate relay terminal) during the discovery process, if, for example, it is among the candidate relay terminals that meet the above relay selection criteria / conditions and / or suitable relay terminals (from the perspective of radio link quality and / or the perspective of the upper layer), the last relay (and / or other intermediate relay terminal) is included. The intermediate relay terminal can then establish a PC5 connection with the last relay terminal.

[0232] The first relay terminal will only select / reselect the aforementioned intermediate relay if, during the discovery process, it searches for intermediate relay terminals that can connect to the base station. For example, if there are candidate relay terminals that meet the aforementioned relay selection criteria / conditions, and / or suitable relay terminals (from the perspective of radio link quality and / or the perspective of the upper layer), and / or a relay terminal among the aforementioned relay terminals that is in a state of being able to connect to the base station (e.g., the aforementioned relay terminal is connected to the last relay terminal connected to the base station), the first relay terminal can establish a PC5 connection with the aforementioned last relay terminal.

[0233] The remote terminal will only select / reselect the first relay during the discovery process if, for example, there are candidate relay terminals that meet the above-mentioned relay selection criteria / conditions, and / or (from the perspective of radio link quality and / or the perspective of the upper layer) suitable relay terminals, and / or among the above relay terminals, a relay terminal in a state of being able to connect to a base station (e.g., the above relay terminal is connected to an intermediate relay terminal, and the intermediate relay terminal is connected to the base station). The remote terminal can establish a PC5 connection with the above-mentioned first relay terminal.

[0234] Subsequently, the remote terminal can perform the RRC establishment process with the base station through multiple relay terminals.

[0235] As another example, when discovery and / or PC5 connection establishment are achieved between the remote terminal and / or the sidelink relay terminal in any order, the remote terminal can perform the RRC establishment process with the base station through multiple sidelink relay terminals.

[0236] For example, the discovery process between the remote terminal and the first relay terminal, between the first relay terminal and intermediate relay terminals, and between intermediate relay terminals and the last relay terminal can be performed (defined as the same steps or different steps). Afterwards, the remote terminal can perform the RRC establishment process with the base station through multiple relay terminals.

[0237] In another example, the discovery process between the remote terminal and the first relay terminal, between the first relay terminal and intermediate relay terminals, and between the intermediate relay terminal and the last relay terminal can be performed (defined as the same or different steps). Afterwards, the PC5 connection establishment process between the remote terminal and the first relay terminal, between the first relay terminal and intermediate relay terminals, and between the intermediate relay terminal and the last relay terminal can be performed (defined as the same or different steps). Subsequently, the remote terminal can perform the RRC establishment process with the base station through multiple relay terminals.

[0238] As described above, this embodiment can effectively control the connection of multi-hop side link relay terminals.

[0239] The structure of the final relay terminal and intermediate relay terminals performing the aforementioned operations is briefly described again below. Remote terminals and base stations can also be configured for the aforementioned multi-hop relay operations.

[0240] Figure 11 This is a diagram illustrating the structure of an intermediate relay terminal according to an embodiment.

[0241] Reference Figure 11The intermediate relay terminal 1100 that performs connection control for multi-hop relay operation in the sidelink network may include: a receiving unit 1130 that receives system information for multi-hop sidelink relay operation; and a transmitting unit 1120 that transmits a discovery message, the discovery message including at least one of RRC connection information and hop count information connected to the base station.

[0242] For example, the intermediate relay terminal 1100 can be configured to simultaneously perform relay terminal operations and remote terminal operations. The intermediate relay terminal 1100 may include relay terminal functionality for relaying data between a remote terminal and a parent terminal. Furthermore, the intermediate relay terminal 1100 may include remote terminal functionality for operating as a remote terminal.

[0243] The intermediate relay terminal 1100 can operate in the same manner as a remote terminal to transmit data to or receive data from a higher-level relay terminal. Furthermore, the intermediate relay terminal 1100 can operate in the same manner as a relay terminal to transmit data to or receive data from a lower-level relay terminal or a remote terminal.

[0244] The receiving unit 1130 can receive side-link RRC messages from the parent relay terminal. The parent relay terminal is the relay terminal above the intermediate relay terminal, which can be another intermediate relay terminal or the last relay terminal.

[0245] The receiving unit 1130 can receive system information transmitted by the base station. It can also receive system information directly from the base station. Alternatively, it can receive system information from the last relay terminal or the parent relay terminal.

[0246] For example, the system information may include at least one of indication information and discovery threshold information indicating whether multi-hop side-link relay operation is supported. The indication information indicating whether multi-hop side-link relay operation is supported indicates whether the base station is capable of supporting the multi-hop side-link relay operation of this disclosure. For example, the indication information may indicate whether the base station has side-link multi-hop relay support functionality. Therefore, the indication information may consist of 1 bit.

[0247] Furthermore, the discovery threshold information may include thresholds for multi-hop side traverse trunk connections. For example, the threshold may represent the RSRP value. The discovery threshold information may represent the SD-RSRP threshold used by the intermediate trunk terminal 1100 to evaluate the AS layer conditions for the discovery operation. When performing multi-hop side traverse trunk discovery, the intermediate trunk terminal may evaluate the AS layer conditions by applying the discovery threshold in order to determine whether to transmit a discovery request message.

[0248] Additionally, the system information is SIB12, which may contain configuration information for the operational side leglink trunk.

[0249] The control unit 1110 can store the information contained in the system information in the intermediate relay terminal. In addition, the control unit 1110 can also use the configuration information in the system information to configure entities such as those used for relay operations in the terminal.

[0250] For example, the discovery message can be one of a discovery announcement message, a discovery request (solicitation) message, or a discovery response message. The control unit 1110 can use the aforementioned system information to execute the discovery process. The discovery process may include various operations.

[0251] For example, the transmitting unit 1120 can transmit information about whether sidelink trunking operation is supported by transmitting a discovery announcement message. As another example, the transmitting unit 1120 can perform a connection operation with a parent or child trunking terminal to establish a sidelink trunking connection by transmitting a discovery request message. As yet another example, the transmitting unit 1120 can perform a connection operation with the parent or child trunking terminal that transmitted the discovery request message by transmitting a discovery response message.

[0252] The discovery message may include at least one of the following: information on whether an RRC connection exists, as described above, and information on the number of hops connected to the base station. For example, the information on whether an RRC connection exists may indicate whether the intermediate relay terminal 1100 is in an RRC connection state. Alternatively, the information on whether an RRC connection exists may include information indicating whether the intermediate relay terminal 1100 is capable of entering an RRC connection state. The information on the number of hops connected to the base station may include a count value that counts the number of hops between the intermediate relay terminal 1100 and the base station. In addition, the discovery message may also include a maximum hop limit (Hoplimit) that the intermediate relay terminal 1100 can connect to the base station.

[0253] In addition, it can be determined whether to transmit a discovery message based on the signal strength information of the discovery request message received from the child relay node and the discovery threshold information contained in the system information.

[0254] For example, the receiving unit 1130 may receive a discovery request message from a sub-relay terminal. The control unit 1110 may determine whether to transmit the discovery message based on a comparison between the signal strength information of the received discovery request message and the discovery threshold information. For example, if the received signal strength of the discovery request message exceeds the discovery threshold (or is above the discovery threshold), the control unit 1110 may determine to transmit the discovery message.

[0255] The discovery message can be a discovery request message or a discovery response message.

[0256] For example, if the control unit 1110 receives a discovery request message from a child relay terminal with a signal strength exceeding the discovery threshold, the control unit can perform control by transmitting the discovery request message to the parent relay terminal. The discovery request message may include indication information such as whether an RRC connection is established, hop count information, and hop count limit information, as described above.

[0257] In another example, if the control unit 1110 already has a parent relay terminal (e.g., the last relay terminal) and a link according to the PC5 interface, if the signal strength of the discovery request message exceeds the discovery threshold, control can be performed by transmitting a discovery response message to the child relay terminal.

[0258] Furthermore, the control unit 1110 controls the overall operation of the intermediate relay terminal 1100 according to the connection control operation, which is performed based on the multi-hop relay operation of the side link required for the execution of this disclosure.

[0259] The transmitting unit 1120 and the receiving unit 1130 are used to transmit signals or messages or data required for executing the aforementioned embodiment to relay terminals, remote terminals, etc., or to receive signals or messages or data required for executing the aforementioned embodiment from relay terminals, remote terminals, etc.

[0260] Figure 12 This is a diagram illustrating the structure of the last relay terminal in one embodiment.

[0261] Reference Figure 12 The last relay terminal 1200 that performs connection control operations for multi-hop relay operations in the sidelink network may include: a receiving unit 1230 that receives system information for multi-hop sidelink relay operations from a base station and receives a discovery request (solicitation) message from a sub-relay terminal; a control unit 1210 that determines whether to transmit a discovery response message based on the discovery request message and the system information; and a sending unit 1220 that transmits the discovery response message to the aforementioned sub-relay terminal.

[0262] The receiving unit 1230 can receive system information transmitted by the base station. System information can be received via SIB12.

[0263] For example, the system information may include at least one of indication information and discovery threshold information indicating whether multi-hop side-link relay operation is supported. The indication information indicating whether multi-hop side-link relay operation is supported indicates whether the base station is capable of supporting the multi-hop side-link relay operation of this disclosure. For example, the indication information may indicate whether the base station has side-link multi-hop relay support functionality. Therefore, the indication information may consist of 1 bit.

[0264] Furthermore, the discovery threshold information may include thresholds for multi-hop side traverse trunk connections. For example, the threshold may represent the RSRP value. The discovery threshold information may represent the SD-RSRP threshold used by the intermediate trunk terminal, the last trunk terminal, or the first trunk terminal to evaluate the AS layer conditions for the discovery operation. When performing multi-hop side traverse trunk discovery, in order to determine whether to transmit a response message regarding the discovery request message, the control unit 1210 may evaluate the AS layer conditions by applying the discovery threshold.

[0265] The control unit 1210 can store the information contained in the system information in the last relay terminal. In addition, the control unit 1210 can also use the configuration information in the system information to configure entities such as those used for relay operations in the terminal.

[0266] Additionally, the receiving unit 1230 can receive discovery request messages transmitted by lower-level sub-relay terminals. A sub-relay terminal can refer to an intermediate relay terminal whose PC5 interface link with the last relay terminal is not connected.

[0267] The control unit 1210 can perform a connection operation with a sub-relay terminal by transmitting a discovery response message, wherein the sub-relay terminal transmits a discovery request message. Therefore, the control unit 1210 can determine whether to transmit a discovery response message in response to the discovery request message.

[0268] For example, the control unit 1210 can determine whether to transmit a discovery response message based on the signal strength information of the discovery request message and the discovery threshold information included in the system information. For instance, if the signal strength information exceeds the discovery threshold information, the control unit 1210 can determine to transmit a discovery response message to the sub-relay terminal. That is, if the received discovery request message shows a reception strength above the discovery threshold, the control unit 1210 can determine to transmit a discovery response message. Here, the reception strength can be the RSRP value.

[0269] The discovery request message or discovery response message may contain at least one of the following: information on whether an RRC connection exists and hop count information for connection to the base station. For example, the RRC connection information may indicate whether the last relay terminal or intermediate relay terminal is in an RRC connection state. Alternatively, the RRC connection information may include information indicating whether the intermediate relay terminal or last relay terminal is capable of entering an RRC connection state. The hop count information for connection to the base station may include a count value representing the number of hops the intermediate relay terminal or last relay terminal has connected to the base station. Furthermore, the discovery request message or discovery response message may also include a maximum hop limit (Hop limit) that the intermediate relay terminal or last relay terminal can connect to the base station.

[0270] The transmitting unit 1220 may transmit a discovery response message to the sub-relay terminal based on the aforementioned determination result of whether to transmit the discovery response message.

[0271] Furthermore, the control unit 1210 controls the overall operation of the last relay terminal 1200 according to the connection control operation, which is performed based on the multi-hop relay operation of the side link required for the execution of this disclosure.

[0272] The transmitting unit 1220 and the receiving unit 1230 are used to transmit signals or messages or data required for executing the aforementioned disclosure to relay terminals, base stations, and remote terminals, or to receive signals or messages or data required for executing the aforementioned disclosure from relay terminals, base stations, and remote terminals.

[0273] Thus, the remote terminal can connect sequentially to the sub-relay terminal (the first relay terminal), the intermediate relay terminal, and the last relay terminal to establish a multi-hop side-link relay connection.

[0274] In addition, the base station can be configured to include a control unit, a transmitting unit, and a receiving unit.

[0275] The control unit controls the overall operation of the base station, which is used to support the transmission or reception of data by performing the side-link multi-hop relay operation required in this embodiment.

[0276] The transmitting unit and the receiving unit are used to transmit signals or messages or data required for executing the present disclosure to relay terminals, remote terminals, etc., or to receive signals or messages or data required for executing the present disclosure from relay terminals, remote terminals, etc.

[0277] In addition, the remote terminal can also be configured to include a receiving unit, a control unit, and a transmitting unit.

[0278] The receiving unit receives downlink control information, data, and messages from the relay terminal or base station through the aforementioned channel.

[0279] In addition, the control unit controls the operation of the overall remote terminal based on the connection control operation via the side link multi-hop relay operation.

[0280] The transmitting unit transmits uplink control information, data, and messages to relay terminals, base stations, etc., through the aforementioned channels.

[0281] The above embodiments can be supported by standard documents disclosed in at least one of IEEE 802, 3GPP, and 3GPP2, which are wireless access systems. That is, steps, components, and parts not described in this embodiment for the purpose of clearly revealing the technical concept can be supported by the aforementioned standard documents. Furthermore, all terms disclosed in this specification can be interpreted using the aforementioned published standard documents.

[0282] The above embodiment can be implemented by various means. For example, this embodiment can be implemented by hardware, firmware, software, or a combination thereof.

[0283] When implemented in hardware, the method according to this embodiment can be implemented by one or more ASICs (Application Specific Integrated Circuits), DSPs (Digital Signal Processors), DSPDs (Digital Signal Processing Devices), PLDs (Programmable Logic Devices), FPGAs (Field Programmable Gate Arrays), processors, controllers, microcontrollers, or microprocessors.

[0284] When implemented via firmware or software, the method according to this embodiment can be implemented in the form of an apparatus, process, or function that performs the functions or operations described above. The software code can be stored in a storage unit and driven by a processor. The storage unit is located inside or outside the processor and can exchange data with the processor through various known devices.

[0285] Furthermore, the terms "system," "processor," "controller," "component," "module," "interface," "model," or "unit" mentioned above can generally refer to computer-related physical hardware, combinations of hardware and software, software, or running software. For example, the aforementioned components can be processes driven by a processor, processors, controllers, control processors, entities, execution threads, programs, and / or computers, but are not limited to these. For example, an application running in a controller or processor, and the controller or processor itself, can both be components. More than one component can reside within a process and / or execution thread, and components can reside in a single device (e.g., a system, a computing device, etc.) or be distributed across two or more devices.

[0286] The above description is merely an exemplary illustration of the technical concept of this disclosure. Those skilled in the art can make various modifications and changes without departing from the essential characteristics of this application. Furthermore, these embodiments are intended to illustrate the technical concept of this disclosure and not to limit it; therefore, the scope of this technical concept is not limited by these embodiments. The scope of protection of this disclosure should be interpreted in accordance with the following claims, and all technical concepts within the same scope should be interpreted as being included within the scope of the rights of this disclosure.

Claims

1. A connection control method for an intermediate relay terminal providing multi-hop relay operation in a sidelink network, comprising: Steps for receiving system information for multi-hop side link relay operations; as well as The step of transmitting a discovery message, wherein the discovery message contains at least one of information on whether an RRC connection is established and hop count information on connection to a base station.

2. The method according to claim 1, wherein, The system information includes at least one of indication information and discovery threshold information for indicating whether multi-hop side-link relay operation is supported.

3. The method according to claim 1, wherein, The discovery message can be any one of a discovery announcement message, a discovery request message, or a discovery response message.

4. The method according to claim 1, wherein, Based on the signal strength information of the discovery request message received from the sub-relay terminal and the discovery threshold information included in the system information, it is determined whether to transmit the discovery message.

5. The method according to claim 4, wherein, In the step of transmitting the discovery message, If the signal strength information exceeds the detection threshold, the detection message is transmitted to the sub-relay terminal. The discovery message is a discovery response message.

6. A connection control method for the last relay terminal providing multi-hop relay operation in a sidelink network, comprising: Steps for receiving system information from a base station for multi-hop side crosslink relay operations: The steps for receiving a discovery request message from a sub-relay terminal; The step of determining whether to transmit a discovery response message based on the discovery request message and the system information; as well as The step of transmitting the discovery response message to the sub-relay terminal.

7. The method according to claim 6, wherein, The system information includes at least one of indication information and discovery threshold information for indicating whether multi-hop side-link relay operation is supported.

8. The method according to claim 6, wherein, The sub-relay terminal is an intermediate relay terminal that is not connected to the last relay terminal and the PC5 interface link.

9. The method according to claim 6, wherein, Based on the signal strength information of the discovery request message and the discovery threshold information included in the system information, determine whether to transmit the discovery response message.

10. The method according to claim 9, wherein, In the step of determining whether to transmit the discovery message, the determination is made in the following manner: If the signal strength information exceeds the detection threshold information, the detection response message is transmitted to the sub-relay terminal.

11. The method according to claim 6, wherein, The discovery request message or the discovery response message contains at least one of the following: information on whether an RRC connection is established and hop count information on the connection to the base station.

12. An intermediate relay terminal performing connection control for multi-hop relay operation in a sidelink network, comprising: The receiving unit receives system information for multi-hop side link relay operations; as well as The transmitting unit transmits a discovery message, which includes at least one of information on whether an RRC connection is established and hop count information on the connection to the base station.

13. The intermediate relay terminal according to claim 12, wherein, The system information includes at least one of indication information and discovery threshold information for indicating whether multi-hop side-link relay operation is supported.

14. The intermediate relay terminal according to claim 12, wherein, The discovery message can be any one of a discovery announcement message, a discovery request message, or a discovery response message.

15. The intermediate relay terminal according to claim 12, wherein, Based on the signal strength information of the discovery request message received from the sub-relay terminal and the discovery threshold information included in the system information, it is determined whether to transmit the discovery message.

16. The intermediate relay terminal according to claim 15, wherein, If the signal strength information exceeds the detection threshold information, the transmitting unit transmits the detection message to the sub-relay terminal. The discovery message is a discovery response message.

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