Method and apparatus for supporting plurality of bearers for low-latency service of QOS flow in wireless communication system

Abstract

The present disclosure is to support a higher data transmission rate by: transmitting a UE capability information message to a base station; when the UE capability information message indicates that a multi-DRB function is supported, in which a plurality of DRBs are available for a single QoS flow, receiving configuration information for each of the plurality of DRBs from the base station via RRC signaling; when the plurality of DRBs are configured to be used for the single QoS flow via RRC signaling, using the plurality of DRBs for the single QoS flow; and when one primary DRB among the plurality of DRBs is configured to be used for the single QoS flow via RRC signaling, using a first DRB among the plurality of DRBs for the single QoS flow.

Description

Method and device for supporting multiple bearers for low-latency service of QOS FLOW in a wireless communication system

[0001] The present disclosure relates to a technology that supports multiple bearers in a wireless communication system.

[0002] 5G mobile communication technology defines a wide frequency band to enable fast transmission speeds and new services, and can be implemented not only in frequency bands below 6 GHz ('Sub 6 GHz'), such as 3.5 gigahertz (3.5 GHz), but also in ultra-high frequency bands called millimeter waves (mmWave), such as 28 GHz and 39 GHz ('Above 6 GHz'). In addition, for 6G mobile communication technology, which is referred to as a system beyond 5G, implementation in the terahertz (THX) band (e.g., the 3 terahertz band at 95 GHz) is being considered to achieve transmission speeds 50 times faster and ultra-low latency reduced to one-tenth compared to 5G mobile communication technology.

[0003] In the early stages of 5G mobile communication technology, aiming to satisfy service support and performance requirements for enhanced Mobile BroadBand (eMBB), Ultra-Reliable Low-Latency Communications (URLLC), and Massive Machine-Type Communications (mMTC), technologies included beamforming and Massive MIMO to mitigate path loss and increase transmission distance in ultra-high frequency bands; support for various numerologies (such as operating multiple subcarrier spacings) and dynamic operation of slot formats for the efficient utilization of ultra-high frequency resources; initial access techniques to support multi-beam transmission and broadband; the definition and operation of Band-Width Parts (BWP); Low Density Parity Check (LDPC) codes for high-volume data transmission; new channel coding methods such as Polar Codes for the reliable transmission of control information; and L2 pre-processing (L2 Standardization has been carried out for pre-processing, network slicing which provides a dedicated network specialized for specific services, and other methods.

[0004] Currently, discussions are underway to improve and enhance the performance of the initial 5G mobile communication technology, taking into account the services that the 5G mobile communication technology was intended to support. Additionally, standardization of the physical layer is in progress for technologies such as V2X (Vehicle-to-Everything), which helps autonomous vehicles make driving decisions and enhance user convenience based on their own location and status information transmitted by the vehicle; NR-U (New Radio Unlicensed), which aims for system operation in unlicensed bands to comply with various regulatory requirements; NR terminal low power consumption technology (UE Power Saving); Non-Terrestrial Network (NTN), which is direct terminal-satellite communication for securing coverage in areas where communication with the terrestrial network is impossible; and positioning.

[0005] In addition, standardization is underway in the field of wireless interface architecture / protocols for technologies such as the Industrial Internet of Things (IIoT) for supporting new services through linkage and convergence with other industries, Integrated Access and Backhaul (IAB) which provides nodes for expanding network service areas by integrating wireless backhaul links and access links, Mobility Enhancement including Conditional Handover and Dual Active Protocol Stack (DAPS) Handover, and 2-step Random Access (2-step RACH for NR) which simplifies random access procedures. Standardization is also underway in the field of system architecture / services for 5G baseline architectures (e.g., Service based Architecture, Service based Interface) for incorporating Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and Mobile Edge Computing (MEC), which provides services based on the location of the terminal.

[0006] When such 5G mobile communication systems are commercialized, connected devices, which are increasing explosively, will be connected to communication networks. Accordingly, it is expected that there will be a need to enhance the functionality and performance of 5G mobile communication systems and to integrate the operation of connected devices. To this end, new research is planned to be conducted on 5G performance improvement and complexity reduction, support for AI services, support for metaverse services, and drone communication using eXtended Reality (XR), Artificial Intelligence (AI), and Machine Learning (ML) to efficiently support Augmented Reality (AR), Virtual Reality (VR), and Mixed Reality (MR).

[0007] Furthermore, the advancement of these 5G mobile communication systems encompasses multi-antenna transmission technologies such as new waveforms to guarantee coverage in the terahertz band of 6G mobile communication technology, Full Dimensional MIMO (FD-MIMO), array antennas, and large-scale antennas; metamaterial-based lenses and antennas to improve terahertz band signal coverage; high-dimensional spatial multiplexing technology using OAM (Orbital Angular Momentum); and Reconfigurable Intelligent Surface (RIS) technology; as well as Full Duplex technology for enhancing frequency efficiency and system networks in 6G mobile communication technology; AI-based communication technologies that realize system optimization by utilizing satellites and AI from the design stage and internalizing end-to-end AI support functions; and the realization of services of complexity exceeding the limits of terminal computing capabilities by utilizing ultra-high-performance communication and computing resources. It could serve as a foundation for the development of next-generation distributed computing technologies.

[0008] As a result of the aforementioned developments and advancements in mobile communication systems, it has become possible to provide a variety of services, and thus measures to effectively provide these services are required.

[0009] Based on the discussion above, the present disclosure aims to provide a method and apparatus for supporting a plurality of bearers for low-latency service of QoS Flow in a wireless communication system.

[0010] The present invention, for solving the above-mentioned problems, may include a method for processing a control signal in a wireless communication system, comprising: receiving a first control signal transmitted from a base station; processing the received first control signal; and transmitting a second control signal generated based on the processing to the base station.

[0011] According to one embodiment of the present disclosure, a multi-DRB mode in which a plurality of bearers are mapped to a QoS flow and a single-DRB mode in which a single bearer is mapped to a QoS flow may be supported.

[0012] According to one embodiment of the present disclosure, mode switching to a multi-DRB mode or a single-DRB mode is possible, so that an optimal service mode can be determined according to the traffic of the QoS flow.

[0013] The effects obtainable in the present disclosure are not limited to those mentioned in the various embodiments, and other unmentioned effects will be clearly understood by those skilled in the art to which the present disclosure pertains from the description below.

[0014] FIG. 1 is a drawing illustrating the structure of an NR system according to one embodiment of the present disclosure.

[0015] FIG. 2 is a diagram showing a wireless protocol structure in an NR system according to one embodiment of the present disclosure.

[0016] FIG. 3 is a diagram illustrating a procedure for a terminal to establish a connection with a network according to one embodiment of the present disclosure.

[0017] FIG. 4 is a diagram illustrating the mapping relationship between QoS Flow and DRB according to one embodiment of the present disclosure.

[0018] FIG. 5 is a diagram illustrating a Multi-DRB mode activation operation according to one embodiment of the present disclosure.

[0019] FIG. 6 is a diagram illustrating an in-order delivery operation for a QoS Flow operating in Multi-DRB mode according to one embodiment of the present disclosure.

[0020] FIG. 7 illustrates the structure of a terminal according to one embodiment of the present disclosure.

[0021] FIG. 8 illustrates the structure of a base station according to one embodiment of the present disclosure.

[0022] The operating principles of the present disclosure will be described in detail below with reference to the attached drawings. In describing the present disclosure below, specific descriptions of related known functions or configurations will be omitted if it is determined that such detailed descriptions would unnecessarily obscure the essence of the present disclosure. Furthermore, the terms described below are defined in consideration of their functions in the present disclosure, and these may vary depending on the intentions or practices of the user or operator. Therefore, their definitions should be based on the content throughout this specification.

[0023] In describing the embodiments of this disclosure, technical details that are well known in the technical field to which this disclosure belongs and are not directly related to this disclosure are omitted. This is intended to convey the essence of this disclosure more clearly without obscuring it by omitting unnecessary explanations.

[0024] For the same reason, some components in the attached drawings have been exaggerated, omitted, or schematically depicted. Additionally, the size of each component does not entirely reflect its actual dimensions. Identical or corresponding components in each drawing have been assigned the same reference numbers.

[0025] The advantages and features of the present disclosure and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below but may be implemented in various different forms. The embodiments provided are merely to make the present disclosure complete and to fully inform those skilled in the art of the scope of the disclosure, and the present disclosure is defined only by the scope of the claims. Throughout the specification, the same reference numerals refer to the same components.

[0026] At this time, it will be understood that each block of the process flow diagrams and combinations of the flow diagrams can be executed by computer program instructions. Since these computer program instructions can be loaded into the processor of a general-purpose computer, a special-purpose computer, or other programmable data processing equipment, the instructions executed through the processor of the computer or other programmable data processing equipment create means to perform the functions described in the flow diagram block(s). Since these computer program instructions can also be stored in computer-available or computer-readable memory that can be directed toward the computer or other programmable data processing equipment to implement the function in a specific way, the instructions stored in computer-available or computer-readable memory can also produce a manufactured item containing instruction means to perform the function described in the flow diagram block(s). Since computer program instructions can be loaded onto a computer or other programmable data processing equipment, instructions that perform a series of operation steps on the computer or other programmable data processing equipment to create a process executed by the computer can also provide steps for executing the functions described in the flowchart block(s).

[0027] Additionally, each block may represent a module, segment, or part of code containing one or more executable instructions for executing a specified logical function(s). It should also be noted that in some alternative execution examples, the functions mentioned in the blocks may occur out of order. For instance, two blocks described in succession may actually be executed substantially simultaneously, or the blocks may be executed in reverse order according to their corresponding functions.

[0028] In this embodiment, the term "part" refers to a software or hardware component such as an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit), and the "part" performs certain roles. However, the meaning of "part" is not limited to software or hardware. The "part" may be configured to reside in an addressable storage medium or may be configured to run one or more processors. Accordingly, as an example, the "part" includes components such as software components, object-oriented software components, class components, and task components, as well as processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functions provided within the components and "parts" may be combined into a smaller number of components and "parts" or further separated into additional components and "parts." In addition, the components and '~parts' may be implemented to play one or more CPUs within the device or secure multimedia card.

[0029] Hereinafter, a base station is an entity that performs resource allocation for terminals and may be at least one of a Node B, BS (Base Station), eNB (eNode B), gNB (gNode B), a radio access unit, a base station controller, or a node on a network. A terminal may include a UE (User Equipment), MS (Mobile Station), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing communication functions. Furthermore, embodiments of the present disclosure may be applied to other communication systems having a technical background or channel type similar to the embodiments of the present disclosure described below. Additionally, embodiments of the present disclosure may be applied to other communication systems with some modifications made at the discretion of a person with skilled technical knowledge, provided that they do not deviate significantly from the scope of the present disclosure. For example, 5th generation mobile communication technology (5G, new radio, NR) developed after LTE-A may be included therein, and the 5G below may be a concept that includes existing LTE, LTE-A, and other similar services. In addition, the present disclosure may be applied to other communication systems with some modifications made at the discretion of a person with skilled technical knowledge, without significantly departing from the scope of the present disclosure.

[0030] Terms used in the following description to identify connection nodes, terms referring to network entities or network functions (NFs), terms referring to messages, terms referring to interfaces between network entities, terms referring to various identification information, etc., are examples provided for the convenience of explanation. Accordingly, the present disclosure is not limited to the terms described below, and other terms referring to objects having equivalent technical meanings may be used.

[0031] For convenience of explanation below, some terms and names defined in the 3GPP (3rd generation partnership project) LTE (long term evolution) standards and / or 3GPP NR (new radio) standards may be used. However, the present disclosure is not limited by these terms and names and may be equally applied to systems conforming to other standards.

[0032] FIG. 1 is a drawing illustrating the structure of an NR system according to one embodiment of the present disclosure.

[0033] Referring to FIG. 1, a wireless communication system according to one example of the present disclosure may be composed of several base stations (e.g., gNB (100), ng-eNB (110), ng-eNB (120), gNB (130)), an Access and Mobility Management Function (AMF) (140), and a User Plane Function (UPF) (150). Of course, the wireless communication system is not limited to the configuration shown in FIG. 1 and may include more or fewer components.

[0034] According to one embodiment of the present disclosure, a user terminal (User Equipment, hereinafter UE or terminal) (160) can connect to an external network through base stations (100, 110, 120, 130) and a UPF (150).

[0035] In FIG. 1, base stations (100, 110, 120, 130) can provide wireless access to terminals connected to the network as access nodes of a cellular network. For example, base stations (100, 110, 120, 130) can support the connection between terminals and a core network (CN; in particular, the CN of NR (new radio) is referred to as 5GC) by collecting state information such as the buffer state, available transmission power state, and channel state of terminals to service the traffic of users and scheduling.

[0036] In FIG. 1, gNB (100, 130) can control multiple cells, and an Adaptive Modulation & Coding (hereinafter AMC) method can be applied to determine a modulation scheme and a channel coding rate according to the channel state of the terminal (160).

[0037] The core network is a device responsible for various control functions as well as mobility management functions for terminals, and can be connected to multiple base stations. In addition, 5GC can be interoperable with existing LTE systems.

[0038] Meanwhile, in a wireless communication system, a User Plane (UP) related to the transmission of actual user data and a Control Plane (CP) related to connection management can be configured separately. The gNB (100) and gNB (130) of FIG. 1 can use UP and CP technologies defined in NR technology, and the ng-eNB (110) and ng-eNB (120) are connected to 5GC but can use UP and CP technologies defined in LTE (Long Term Evolution) technology.

[0039] The AMF (140) is a device responsible for various control functions as well as mobility management functions for the terminal, and can be connected to multiple base stations.

[0040] UPF (150) may refer to a type of gateway device that provides data transmission. Although not shown in FIG. 1, the NR wireless communication system may include a Session Management Function (SMF). The SMF can manage packet data network connections, such as protocol data unit (PDU) sessions provided to terminals.

[0041] FIG. 2 is a diagram showing a wireless protocol structure in an NR system according to one embodiment of the present disclosure.

[0042] Referring to FIG. 2, the wireless protocol of the NR system can be composed of SDAP (Service Data Adaptation Protocol) (200)(290), PDCP (Packet Data Convergence Protocol) (210)(280), RLC (Radio Link Control) (220)(270), MAC (Medium Access Control) (230)(260), and PHY (Physical) (240)(250) at the terminal and base station, respectively.

[0043] SDAP (Service Data Adaptation Protocol) (200) (290) can transmit user data and perform operations to map QoS (quality of service) flows for uplink and downlink to specific DRBs (data radio bearers), to mark QoS flow IDs (identities) for uplink and downlink, and to map reflective QoS flows for uplink SDAP PDUs to data bearers. SDAP configurations corresponding to each DRB may be provided by the upper RRC (radio resource control) layer. Of course, this is not limited to the example.

[0044] The PDCP (Packet Data Convergence Protocol) (210) (280) can perform operations such as compressing and decompressing IP (internet protocol) headers. Additionally, the PDCP (210) (280) can provide sequential and non-sequential delivery functions, reorder the data, detect duplicates, retransmit data, and provide encryption and decryption functions. Of course, it is not limited to these examples.

[0045] Radio Link Control (220)(270) can reconfigure the PDCP Protocol Data Unit (PDU) to an appropriate size. Additionally, RLC (220)(270) provides sequential and non-sequential delivery functions and can provide ARQ functions, splicing, splitting, reassembling, resegmentation, reordering, duplicate detection, and error detection functions. Of course, it is not limited to these examples.

[0046] The MAC (230)(260) is connected to multiple RLC layer devices configured in a terminal and can perform operations to multiplex RLC PDUs into MAC PDUs and demultiplex RLC PDUs from MAC PDUs. Additionally, the MAC (230)(260) can provide mapping functions, scheduling information reporting functions, HARQ (hybrid automatic repeat request) functions, priority control functions between logical channels, priority control functions between terminals, MBMS (multimedia broadcast multicast service) service verification functions, transmission format selection functions, and padding functions. Of course, it is not limited to these examples.

[0047] The physical (PHY) layer (240)(250) performs the operation of channel coding and modulating upper layer data, converting it into OFDM (orthogonal frequency division multiplexing) symbols and transmitting them over a wireless channel, or demodulating OFDM symbols received through the wireless channel and channel decoding them to transmit them to the upper layer. In addition, the physical layer also uses HARQ (Hybrid ARQ) for additional error correction, and the receiving end transmits a 1-bit information indicating whether the packet transmitted by the transmitting end has been received. This 1-bit information is called HARQ ACK / NACK information.

[0048] In the case of LTE, downlink HARQ ACK / NACK information regarding uplink data transmission can be transmitted via the PHICH (Physical Hybrid-ARQ Indicator Channel) physical channel. In the case of NR, it is possible to determine whether retransmission is necessary or if a new transmission can be performed through the terminal's scheduling information on the PDCCH (Physical Dedicated Control Channel), which is the channel where downlink / uplink resource allocation is transmitted. This is because asynchronous HARQ is applied in NR. Uplink HARQ ACK / NACK information regarding downlink data transmission can be transmitted via the PUCCH (Physical Uplink Control Channel) or PUSCH (Physical Uplink Shared Channel) physical channels. Although PUCCH is generally transmitted on the uplink of the PCell (Primary Cell), if supported by the terminal, the base station may additionally transmit PUCCH to the SCell (Secondary Cell) to the terminal, which is referred to as PUCCH SCell.

[0049] Although not shown in Fig. 2, there is a Radio Resource Control (RRC) layer above the PDCP layer of the terminal and the base station, respectively, and the RRC layer can transmit and receive connection and measurement-related setting control messages for wireless resource control.

[0050] Meanwhile, the physical layer can consist of one or more frequencies / carriers, and the technology of setting and using multiple frequencies simultaneously is called carrier aggregation (hereinafter referred to as CA). Unlike existing technology that used only one carrier for communication between a terminal (or User Equipment, UE) and a base station (eNB or gNB), CA technology uses one or more secondary carriers in addition to the main carrier, thereby significantly increasing the transmission capacity by the number of secondary carriers. Meanwhile, in LTE / NR, a cell within a base station that uses the main carrier is called a primary cell or PCell (Primary Cell), and a cell within a base station that uses a secondary carrier is called a secondary cell or SCell (Secondary Cell).

[0051] FIG. 3 is a diagram illustrating a procedure for a terminal to establish a connection with a network according to one embodiment of the present disclosure.

[0052] FIG. 3 illustrates the procedure in which a terminal in the present disclosure switches from RRC idle mode (RRC_IDLE) to RRC connected mode (RRC_CONNECTED) to establish a connection with a network. In FIG. 3, the terminal establishes uplink / downlink transmission synchronization with the base station through a random access process and transmits an RRCSetupRequest message to the base station (300). The RRCSetupRequest message may contain the terminal's identifier and the reason for establishing the connection (EstablishmentCause), etc. The base station transmits an RRCSetup message to the terminal to establish an RRC connection (305).

[0053] Referring to FIG. 3, the terminal that has established the RRC connection enters RRC_CONNECTED mode and sends an RRCSetupComplete message to the base station (310). If the base station does not know the terminal capability of the terminal currently establishing the connection, or wants to determine the terminal capability, the base station may send a message asking about the terminal's capability (e.g., UECapabilityEnquiry) to the terminal (315). Then, the terminal may send a message reporting the terminal's capability (e.g., UECapabilityInformation) to the base station (320).

[0054] The base station sends a SecurityModeCommand message (325) to the terminal to establish security with the terminal, and the terminal sends a SecurityModeComplete message (330) to the base station.

[0055] Once the security settings are complete, the base station sends an RRCReconfiguration message to the terminal (335). The RRCReconfiguration message may include information elements for radio bearer settings. The terminal may send an RRCReconfigurationComplete message to the base station (340).

[0056] The terminal can apply the new settings received via the RRCReconfiguration message, and the base station can also apply the new settings for the terminal. Data bearers can be configured or modified according to the new settings, and data transmission between the base station and the terminal can be started or resumed. (345).

[0057] As such, the general connection setup process consists of three stages: RRC connection setup, security setup, and DRB setup. Additionally, the base station may send an RRCReconfiguration message to the terminal to provide, add, or change the settings for a specific reason (350).

[0058] In one embodiment, a base station may include additional configuration information (e.g., RadioBearerConfig, drb-ToAddModList, DRB-ToAddMod) or release configuration information (e.g., RadioBearerConfig, drb-ToReleaseList) for one or more Data Radio Bearers (DRBs) in a predetermined RRC message (e.g., RRCSetup / RRCReconfiguration). drb-ToAddModList and DRB-ToAddMod are information elements included in the RadioBearerConfig portion of the RRCReconfiguration message and may contain information for adding or modifying DRBs. While DRB-ToAddMod contains information for a single DRB, drb-ToAddModList may be a set of multiple DRB-ToAddMod structures. A terminal may configure a new DRB based on the DRB additional configuration information or change the configuration of an existing DRB. A terminal may release an existing DRB through the DRB release configuration information. For example, the base station may include at least one of the following settings in the additional DRB setting information.

[0059] - cnAssociation: If the bearer is connected to EPC, it can specify the eps-bearerIdentity associated with that bearer. If the bearer is connected to 5GC, it can specify SDAP configuration information (e.g., sdap-Config). For example, if NR or E-UTRA is connected to 5GC, the SDAP configuration information can establish a mapping relationship between QoS flow and DRB.

[0060] - drb-Identity: Can indicate the DRB ID.

[0061] - pdcp-Config: May contain configuration information for the PDCP layer device of the DRB.

[0062] In one embodiment of the present disclosure, in a DRB configuration, SDAP configuration information (e.g., sdap-Config) can set SDAP parameters that are configurable for the DRB. For example, the SDAP configuration information may include at least one of the following information.

[0063] - pdu-Session: Can indicate the ID of the PDU Session to which the QoS Flow mapped to the DRB belongs.

[0064] - defaultDRB: A BOOLEAN type field that indicates whether the DRB is the default DRB of the PDU Session. For example, since a specific PDU Session can have at most one (or one or zero) default DRBs, among DRBs with the same pdu-Session ID and SDAP settings, only the SDAP setting information of at most one DRB can set the defaultDRB field to TRUE.

[0065] - mappedQoS-FlowsToAdd (e.g., a list type consisting of one or more QFIs (QoS Flow IDs): Can indicate a list containing the QFIs (QoS Flow IDs) of UL QoS Flows mapped to DRB among the PDU Sessions to which the QoS Flow mapped to DRB belongs.

[0066] According to the mapping relationship between the QoS Flow and the DRB in one embodiment, one QoS Flow (420) can be mapped to one DRB (450), and multiple QoS Flows (420, ..., 430) can be mapped to one DRB (450). In this case, depending on the traffic characteristics of the QoS Flow, rapid traffic processing by the DRB may not be possible. For example, if an upper layer / application layer generates a burst of traffic and the traffic must be transmitted within a short period of time, if the service is provided by mapping the QoS Flow to a single DRB, it may be impossible to rapidly process the traffic of the DRB (e.g., PDCP / RLC / MAC layer processing) due to the limitations of the computing power allocated to the DRB internally within the device.

[0067] Accordingly, in the present disclosure, considering traffic characteristics, the QoS Flow is simultaneously mapped to multiple DRBs, thereby enabling rapid processing by utilizing multiple DRB resources simultaneously.

[0068] FIG. 4 is a diagram illustrating the mapping relationship between QoS Flow and DRB according to one embodiment of the present disclosure.

[0069] Referring to FIG. 4, in one embodiment of the present disclosure, a base station may transmit configuration information to a terminal via an RRC message to map a specific QoS Flow (400) to a plurality of DRBs (460, 470). For example, the configuration information may be transmitted via a plurality of additional DRB configuration information (e.g., RadioBearerConfig, drb-ToAddModList, DRB-ToAddMod) included in a predetermined RRC message (e.g., RRCReconfiguration) transmitted by the base station to the terminal. For example, the QoS Flow (400) may be configured to map to a plurality of DRBs (460, 470) by including the QFI of the QoS Flow (400) in the configuration information (e.g., sdap-config, mappedQoS-FlowsToAdd) (440, 450) of the plurality of DRBs (460, 470), respectively.

[0070] In one embodiment of the present disclosure, when a base station configures multiple DRBs to be mapped to a specific QoS Flow via an RRC message, one of the multiple DRBs may be configured as a representative DRB (e.g., Primary DRB). For example, the Primary DRB may be indicated by setting a Primary DRB indicator per DRB / QoS Flow. For example, the Primary DRB indicator may be an indicator indicating the ID of the DRB. For example, the Primary DRB indicator may be a BOOLEAN or 1-bit indicator, configured such that it is indicated as the Primary DRB when the value of the corresponding field is TRUE or 1. Among the multiple DRBs, any DRB other than the Primary DRB may be considered as Secondary DRBs. For example, the base station may configure, via an RRC message, that a specific DRB is the Secondary DRB of a specific QoS Flow through a Secondary DRB indicator. For example, the Secondary DRB indicator may be configured per DRB / QoS Flow. For example, a Secondary DRB indicator may indicate a DRB ID. For example, DRB configuration information (e.g., RadioBearerConfig, drb-ToAddModList, DRB-ToAddMod) may each include a list containing the QoS Flow IDs of QoS Flows where the corresponding DRB is the Primary DRB, and a list containing the QoS Flow IDs of QoS Flows where the corresponding DRB is the Secondary DRB. For example, if multiple DRBs are mapped to a specific QoS Flow, the DRB with the largest or smallest DRB ID among the multiple DRBs may be considered the Primary DRB, and the other DRBs may be considered Secondary DRBs.

[0071] In the present disclosure, a hierarchical entity responsible for the mapping relationship between QoS Flow and DRB may be referred to as an SDAP hierarchical entity. However, the hierarchical entity is not limited to SDAP and may include a new hierarchical entity responsible for the mapping function between QoS Flow and DRB. For example, in the present disclosure, SDAP SDU / PDU may refer to an SDU / PDU of a new hierarchy responsible for the mapping function between QoS Flow and DRB.

[0072] In one embodiment of the present disclosure, an operation of servicing a QoS Flow by simultaneously using multiple DRBs may be referred to as the Multi-DRB mode of the QoS Flow.

[0073] In one embodiment of the present disclosure, an operation of servicing one QoS Flow using one DRB may be referred to as the Single-DRB mode of the QoS Flow.

[0074] In one embodiment of the present disclosure, with respect to the Multi-DRB mode, the terminal may operate as follows.

[0075] An SDAP transmitting device that receives an SDAP SDU of QoS Flow from an upper layer can operate as follows.

[0076] - If a DRB mapping rule is stored for a QoS Flow and there are two or more DRBs mapped to the QoS Flow:

[0077] For example, an SDAP SDU can be mapped to all corresponding DRBs according to the above-mentioned stored mapping rule. For example, an SDAP SDU can be mapped to one of all corresponding DRBs according to the stored mapping rule. For example, which DRB it is mapped to can be determined by the terminal implementation.

[0078] - If there are multiple mapped DRBs as described above, for each DRB:

[0079] --- If the DRB is configured by RRC to have an SDAP header:

[0080] ---- A UL SDAP Data PDU can be generated by the UL SDAP Data PDU format, which has an SDAP header.

[0081] --- If not:

[0082] ---- A UL SDAP Data PDU can be generated by the SDAP Data PDU format, which does not have an SDAP header.

[0083] The generated UL SDAP Data PDU can be delivered to a lower layer (e.g., the corresponding DRB / PDCP layer device).

[0084] - If there is only one mapped DRB above:

[0085] --- If the DRB is configured by RRC to have an SDAP header:

[0086] ---- A UL SDAP Data PDU can be generated by the UL SDAP Data PDU format, which has an SDAP header.

[0087] --- If not:

[0088] ---- A UL SDAP Data PDU can be generated by the SDAP Data PDU format, which does not have an SDAP header.

[0089] The generated UL SDAP Data PDU can be passed to the lower layer.

[0090] In one embodiment of the present disclosure, an SDAP transmitting device that receives an SDAP SDU of QoS Flow from an upper layer may operate as follows.

[0091] - If a DRB mapping rule is stored for a QoS Flow and there are two or more DRBs mapped to the QoS Flow:

[0092] -- If Multi-DRB mode is enabled for QoS Flow:

[0093] For example, SDAP SDUs can be mapped to all corresponding DRBs according to stored mapping rules. For example, SDAP SDUs can be mapped to one of all corresponding DRBs according to stored mapping rules. For example, which DRB to be mapped to can be determined by the terminal implementation.

[0094] -- Otherwise (in Single-DRB mode):

[0095] Based on the stored mapping rules, SDAP SDUs can be mapped to the corresponding Primary DRB / DRB.

[0096] - If there are multiple mapped DRBs above, for each DRB:

[0097] --- If the DRB is configured by RRC to have an SDAP header:

[0098] ---- A UL SDAP Data PDU can be generated by the UL SDAP Data PDU format, which has an SDAP header.

[0099] --- If not:

[0100] ---- A UL SDAP Data PDU can be generated by the SDAP Data PDU format, which does not have an SDAP header.

[0101] The generated UL SDAP Data PDU can be passed to the lower layer.

[0102] - If there is only one mapped DRB above:

[0103] --- If the DRB is configured by RRC to have an SDAP header:

[0104] ---- A UL SDAP Data PDU can be generated by the UL SDAP Data PDU format, which has an SDAP header.

[0105] --- If not:

[0106] ---- A UL SDAP Data PDU can be generated by the SDAP Data PDU format, which does not have an SDAP header.

[0107] The generated UL SDAP Data PDU can be passed to the lower layer.

[0108] FIG. 5 is a diagram illustrating a Multi-DRB mode activation operation according to one embodiment of the present disclosure.

[0109] Referring to FIG. 5, in one embodiment of the present disclosure, a terminal may activate a Multi-DRB mode (520) when condition 1 (510) is satisfied for a specific QoS Flow. For example, condition 1 (510) may include at least one of the following conditions.

[0110] - When multiple DRBs are mapped to a QoS Flow due to the mapping relationship established between the QoS Flow and the DRB included in the RRC message transmitted by the base station (e.g., RRCReconfiguration 500)

[0111] - When an RRC message (e.g., RRCReconfiguration 500) transmitted by the base station contains / sets a Multi-DRB mode activation indicator for the QoS Flow. For example, the activation indicator may be set per QoS Flow / per DRB. For example, if the activation indicator is set per DRB, the DRB containing the activation indicator may be considered as a DRB available for Multi-DRB mode (520). For example, Multi-DRB mode (520) may be activated for the QoS Flow only when there are multiple DRBs with activation indicators set among multiple DRBs mapped to the QoS Flow.

[0112] - When the total buffer size or the data size belonging to the QoS Flow stored in the buffer corresponding to the Primary DRB of the QoS Flow (e.g., the corresponding PDCP buffer and / or RLC buffer) is greater than a specific threshold value set by the base station. For example, the base station may set the threshold value per DRB / per QoS Flow through a predetermined RRC message (e.g., RRCReconfiguration, 500).

[0113] Referring to FIG. 5, in one embodiment of the present disclosure, the terminal may operate in Single-DRB mode (540) when condition 2 (530) is satisfied for a specific QoS Flow. For example, condition 2 (530) may include at least one of the following conditions.

[0114] - When one DRB is mapped to a QoS Flow due to the establishment of a mapping relationship between the QoS Flow and the DRB included in a specific RRC message (e.g., RRCReconfiguration 500) transmitted by the base station

[0115] - When multiple DRBs are mapped to a QoS Flow by the mapping relationship between the QoS Flow and the DRB included in a predetermined RRC message (e.g., RRCReconfiguration 500) transmitted by the base station, but a Multi-DRB mode activation indicator for the QoS Flow is not included or set. For example, the activation indicator may be set per QoS Flow / per DRB. For example, if the activation indicator is set per DRB, the DRB containing the activation indicator may be considered as a DRB available for Multi-DRB mode. For example, if the number of DRBs with an activation indicator set among multiple DRBs mapped to a specific QoS Flow is one, Single-DRB mode (540) may be activated for the QoS Flow.

[0116] - When the total buffer size or the data size belonging to the QoS Flow stored in the buffer corresponding to the Primary DRB of the QoS Flow (e.g., PDCP buffer and / or RLC buffer) is smaller than or equal to a specific threshold value set by the base station. For example, the base station may set the threshold value per DRB / per QoS Flow through a predetermined RRC message (e.g., RRCReconfiguration, 500).

[0117] Referring to FIG. 5, in one embodiment of the present disclosure, a base station may send a Multi-DRB activation signal (550) to a terminal through a specific field of an RRC message / MAC CE / DCI. For example, the Multi-DRB activation signal (550) may include at least one of the following fields.

[0118] - It may include one or more QoS Flow IDs for which Multi-DRB mode is to be enabled. A terminal receiving this may enable Multi-DRB mode for the corresponding QoS Flow. For example, a QoS Flow that does not contain a QoS Flow ID may be instructed to disable Multi-DRB mode.

[0119] - A bit map may be included. For example, a specific bit of the bit map can be mapped to a specific QoS Flow. For example, by setting the bit corresponding to the QoS Flow to be activated to 1, the terminal receiving this can be configured to enable Multi-DRB mode for that QoS Flow. For example, for the QoS Flow corresponding to bit 0, it can be instructed to disable Multi-DRB mode.

[0120] - MAC CE may include an LCID (Logical Channel ID) / eLCID (extended LCID) that can indicate that MAC CE is a MAC CE for Multi-DRB enable signal.

[0121] Referring to FIG. 5, in one embodiment of the present disclosure, a base station may send a Multi-DRB disable signal (570) to a terminal through a specific field of an RRC message / MAC CE / DCI. For example, the Multi-DRB disable signal (570) may include at least one of the following fields.

[0122] - It may include one or more QoS Flow IDs for which Multi-DRB mode is to be disabled. A terminal receiving this may disable Multi-DRB mode for the corresponding QoS Flow. For example, a QoS Flow that does not contain a QoS Flow ID may be instructed to enable Multi-DRB mode.

[0123] - A bit map may be included. For example, a specific bit of the bit map can be mapped to a specific QoS Flow. For example, by setting the bit corresponding to the QoS Flow to be disabled to 1, the terminal receiving this can be configured to disable Multi-DRB mode for that QoS Flow. For example, for the QoS Flow corresponding to bit 0, it can be instructed to enable Multi-DRB mode.

[0124] - MAC CE may include an LCID (Logical Channel ID) / eLCID (extended LCID) that can indicate that MAC CE is a MAC CE for Multi-DRB disable signal.

[0125] In one embodiment of the present disclosure, a terminal that receives a Multi-DRB activation signal (550) can activate the Multi-DRB mode for a QoS Flow instructed to activate the Multi-DRB mode.

[0126] In one embodiment of the present disclosure, a terminal that receives a Multi-DRB disable signal (570) may disable the Multi-DRB mode for a QoS Flow instructed to disable the Multi-DRB mode.

[0127] In one embodiment of the present disclosure, the terminal may transmit data (e.g., SDAP SDU / PDU) of a QoS Flow in which Multi-DRB mode is disabled only to the Primary DRB.

[0128] In one embodiment of the present disclosure, a terminal can transmit data (e.g., SDAP SDU / PDU) of a QoS Flow in which Multi-DRB mode is enabled to all mapped multiple DRBs.

[0129] In one embodiment of the present disclosure, a terminal may transmit data (e.g., SDAP SDU / PDU) of a QoS Flow with Multi-DRB mode enabled to one of a plurality of mapped DRBs. For example, the terminal implementation may determine which of the plurality of DRBs to transmit to.

[0130] In one embodiment of the present disclosure, as described above in step 315 of FIG. 3, a base station may transmit a terminal capability request (UECapabilityEnquiry) message to a terminal in an RRC connection state, requesting a capability report. At this time, the base station may include a terminal capability request by RAT type in the UECapabilityEnquiry message. For example, when the base station requests the terminal to generate a UECapabilityInformation message through the capability request message, it may include filtering information that can indicate conditions and limitations. For example, the filtering information may include frequency band list information requesting a capability report by RAT type. For example, the filtering information may indicate whether the terminal by RAT type needs to report whether it supports a specific function. For example, the filtering information may indicate whether the terminal needs to report whether it supports the Multi-DRB function proposed in the present disclosure, for each specific RAT type (e.g., NR). In response to the base station's UECapabilityEnquiry message, the terminal can compose a UECapabilityInformation message and report it to the base station.

[0131] A terminal according to one example of the present disclosure may include a field in the UECapabilityInformation message indicating whether the terminal supports the Multi-DRB function proposed in the present disclosure. For example, the field indicating whether the Multi-DRB function is supported may be represented by 1-bit information (e.g., 1: supported, 0: not supported). As another example, if the UECapabilityInformation message includes a field indicating whether the Multi-DRB function is supported, it may indicate that the Multi-DRB function is supported, and if the field indicating whether the Multi-DRB function is supported is not included, it may indicate that the Multi-DRB function is not supported.

[0132] A base station can determine whether the terminal supports the Multi-DRB function proposed in the present disclosure through a UECapabilityInformation message transmitted by the terminal. For example, if the base station determines that the terminal supports the Multi-DRB function proposed in the present disclosure, it can transmit Multi-DRB related configuration information to the terminal through an RRCReconfiguration message such as step 335 of FIG. 3.

[0133] FIG. 6 is a diagram illustrating an in-order delivery operation for a QoS Flow operating in Multi-DRB mode according to one embodiment of the present disclosure.

[0134] Referring to FIG. 6, when data of a single QoS Flow is received through multiple DRB / PDCP layer devices, the receiving side can rearrange the order of the data of the corresponding QoS Flow at the SDAP layer (600) and transmit it to the upper layer (640).

[0135] In one embodiment of the present disclosure, when data (1, 2, 3) of a specific QoS Flow is received through three PDCP layer devices (610, 620, 630), the receiving SDAP layer device (600) responsible for the QoS Flow can rearrange the data of the QoS Flow and then transmit it to an upper layer. For example, to rearrange the QoS Flow, the transmitting SDAP layer device can set a QoS Flow / SDAP SN (Sequence Number) indicating which SDU a specific SDAP SDU is in the corresponding QoS Flow in the SDAP UL / DL Data PDU header containing the SDAP SDU.

[0136] In one embodiment of the present disclosure, an SDAP layer device (600) may start a specific Reordering Timer set per QoS flow in the SDAP layer device when an SDAP SDU of a specific QoS Flow is received that corresponds to a non-sequential SN based on the QoS Flow / SDAP SN. For example, a base station may set the size of the Reordering Time per QoS Flow / per SDAP layer device through a predetermined RRC message.

[0137] FIG. 7 is a block diagram illustrating the structure of a terminal according to one embodiment of the present disclosure.

[0138] Referring to FIG. 7, the terminal includes an RF (Radio Frequency) processing unit (710), a baseband processing unit (720), a storage unit (730), and a control unit (740).

[0139] The RF processing unit (710) performs functions for transmitting and receiving signals through a wireless channel, such as signal band conversion and amplification. The RF processing unit (710) up-converts the baseband signal provided by the baseband processing unit (720) into an RF band signal, transmits it through an antenna, and down-converts the RF band signal received through the antenna into a baseband signal. For example, the RF processing unit (710) may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC (digital to analog converter), an ADC (analog to digital converter), etc. Although only one antenna is shown in FIG. 7, the terminal is not limited thereto and may be equipped with multiple antennas. Additionally, the RF processing unit (710) may include multiple RF chains. Furthermore, the RF processing unit (710) may perform beamforming. For beamforming, the RF processing unit (710) can adjust the phase and magnitude of each of the signals transmitted and received through multiple antennas or antenna elements. Additionally, the RF processing unit can perform MIMO and can receive multiple layers when performing MIMO operation.

[0140] The baseband processing unit (720) performs a conversion function between a baseband signal and a bit sequence according to the physical layer specifications of the system. For example, when transmitting data, the baseband processing unit (720) generates complex symbols by encoding and modulating the transmitted bit sequence. Additionally, when receiving data, the baseband processing unit (720) restores the received bit sequence by demodulating and decoding the baseband signal provided by the RF processing unit (710). For example, in the case of an orthogonal frequency division multiplexing (OFDM) method, when transmitting data, the baseband processing unit (720) generates complex symbols by encoding and modulating the transmitted bit sequence, maps the complex symbols to subcarriers, and then constructs the OFDM symbols through inverse fast Fourier transform (IFFT) operations and cyclic prefix (CP) insertion. Additionally, upon receiving data, the baseband processing unit (720) divides the baseband signal provided by the RF processing unit (710) into OFDM symbol units, restores the signals mapped to subcarriers through a fast Fourier transform (FFT), and then restores the received bit sequence through demodulation and decoding.

[0141] The baseband processing unit (720) and the RF processing unit (710) transmit and receive signals as described above. Accordingly, the baseband processing unit (720) and the RF processing unit (710) may be referred to as a transmitting unit, a receiving unit, a transmitting and receiving unit, or a communication unit. Furthermore, at least one of the baseband processing unit (720) and the RF processing unit (710) may include a plurality of communication modules to support a plurality of different wireless access technologies. Additionally, at least one of the baseband processing unit (720) and the RF processing unit (710) may include different communication modules to process signals of different frequency bands. For example, different wireless access technologies may include wireless LAN (e.g., IEEE 802.11), cellular network (e.g., LTE), etc. In addition, different frequency bands may include super high frequency (SHF) bands (e.g., 2 NRHz, NRHz) and millimeter wave (e.g., 60 GHz) bands.

[0142] The storage unit (730) stores data such as basic programs, application programs, and configuration information for the operation of the terminal. In particular, the storage unit (730) can store information related to a second connection node that performs wireless communication using the second wireless connection technology. Additionally, the storage unit (730) provides the stored data upon the request of the control unit (740).

[0143] The control unit (740) controls the overall operations of the terminal. For example, the control unit (740) transmits and receives signals through the baseband processing unit (720) and the RF processing unit (710). Additionally, the control unit (740) writes and reads data to and from the storage unit (740). To this end, the control unit (740) may include at least one processor. For example, the control unit (740) may include a communication processor (CP) that performs control for communication and an application processor (AP) that controls upper layers such as applications. According to various embodiments, the control unit (740) may be configured to perform various operations described below.

[0144] FIG. 8 is a block diagram illustrating the structure of a base station according to one embodiment of the present disclosure.

[0145] As illustrated in the drawing, the base station is configured to include an RF processing unit (810), a baseband processing unit (820), a backhaul communication unit (830), a storage unit (840), and a control unit (850).

[0146] The RF processing unit (810) performs functions for transmitting and receiving signals through a wireless channel, such as signal band conversion and amplification. The RF processing unit (810) upconverts the baseband signal provided by the baseband processing unit (820) into an RF band signal, transmits it through an antenna, and downconverts the RF band signal received through the antenna into a baseband signal. For example, the RF processing unit (810) may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, etc. Although the first connection node in FIG. 8 is depicted as including only one antenna, the first connection node may be equipped with multiple antennas. Additionally, the RF processing unit (810) may include multiple RF chains. Furthermore, the RF processing unit (810) may perform beamforming. For beamforming, the RF processing unit (810) may adjust the phase and magnitude of each of the signals transmitted and received through multiple antennas or antenna elements. The RF processing unit can perform down-to-down MIMO operation by transmitting one or more layers.

[0147] The baseband processing unit (820) performs a conversion function between a baseband signal and a bit sequence according to the physical layer specifications of the first wireless access technology. For example, when transmitting data, the baseband processing unit (820) generates complex symbols by encoding and modulating the transmitted bit sequence. Also, when receiving data, the baseband processing unit (820) restores the received bit sequence by demodulating and decoding the baseband signal provided by the RF processing unit (810). For example, in the case of following the OFDM method, when transmitting data, the baseband processing unit (820) generates complex symbols by encoding and modulating the transmitted bit sequence, maps the complex symbols to subcarriers, and then constructs OFDM symbols through IFFT operation and CP insertion. Additionally, upon receiving data, the baseband processing unit (820) divides the baseband signal provided by the RF processing unit (810) into OFDM symbol units, restores the signals mapped to subcarriers through FFT operations, and then restores the received bit sequence through demodulation and decoding. The baseband processing unit (820) and the RF processing unit (810) transmit and receive signals as described above. Accordingly, the baseband processing unit (820) and the RF processing unit (810) may be referred to as a transmitting unit, a receiving unit, a transmitting and receiving unit, a communication unit, or a wireless communication unit.

[0148] The backhaul communication unit (830) provides an interface for communicating with other nodes within the network. The backhaul communication unit (830) converts a bit sequence transmitted from the main base station to other nodes, e.g., auxiliary base station, core network, etc., into a physical signal, and converts a physical signal received from other nodes into a bit sequence.

[0149] The storage unit (840) stores data such as basic programs, application programs, and configuration information for the operation of the main station. In particular, the storage unit (840) can store information regarding bearers assigned to connected terminals, measurement results reported from connected terminals, etc. Additionally, the storage unit (840) can store information that serves as a criterion for determining whether to provide multiple connections to the terminals or to disconnect them. Furthermore, the storage unit (840) provides the stored data upon the request of the control unit (850).

[0150] The control unit (850) controls the overall operations of the base station. For example, the control unit (850) transmits and receives signals through the baseband processing unit (820) and the RF processing unit (810) or through the backhaul communication unit (830). Additionally, the control unit (850) writes and reads data to and from the storage unit (840). To this end, the control unit (850) may include at least one processor (or controller). According to various embodiments, the control unit (850) may be configured to perform various operations described below.

[0151] Methods according to the embodiments described in the claims or specification of the present invention may be implemented in the form of hardware, software, or a combination of hardware and software.

[0152] When implemented in software, a computer-readable storage medium may be provided for storing one or more programs (software modules). One or more programs stored in the computer-readable storage medium are configured for execution by one or more processors within an electronic device. One or more programs include instructions that cause the electronic device to execute methods according to embodiments described in the claims or specification of the present invention.

[0153] Such programs (software modules, software) may be stored in random access memory, non-volatile memory including flash memory, ROM (Read Only Memory), Electrically Erasable Programmable Read Only Memory (EEPROM), magnetic disc storage devices, Compact Disc-ROM (CD-ROM), Digital Versatile Discs (DVDs), or other forms of optical storage devices, magnetic cassettes. Alternatively, they may be stored in memory composed of some or all of these. Additionally, each constituent memory may include multiple units.

[0154] In addition, the above program may be stored on an attachable storage device that can be accessed via a communication network such as the Internet, Intranet, Local Area Network (LAN), Wide LAN (WLAN), or Storage Area Network (SAN), or a combination thereof. Such a storage device may be connected to a device performing an embodiment of the present invention through an external port. Additionally, a separate storage device on a communication network may be connected to a device performing an embodiment of the present invention.

[0155] In the specific embodiments of the present invention described above, the components included in the invention are expressed in a singular or plural form according to the specific embodiments presented. However, the singular or plural expression is selected to suit the situation presented for convenience of explanation, and the present invention is not limited to singular or plural components; even if a component is expressed in the plural form, it may be composed in the singular form, or even if a component is expressed in the singular form, it may be composed in the plural form.

[0156] Meanwhile, although specific embodiments have been described in the detailed description of the present invention, it is understood that various modifications are possible within the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined by the claims set forth below as well as equivalents thereof.

Claims

1. A method performed by UE (user equipment) in a wireless communication system, A step of transmitting a terminal capability information message to a base station (320); Based on the terminal capability information message indicating that a Multi-DRB function is supported in which multiple DRBs are available for a single QoS (quality of service) flow, the step (325) of receiving configuration information for each of the multiple DRBs from the base station via RRC (radio resource control) signaling, wherein the configuration information for each of the multiple DRBs includes a QFI list including a QoS flow identifier (QoS flow identifier) ​​of at least one QoS flow in which each DRB can be used; When the plurality of DRBs are configured to be used for the single QoS flow through the above RRC signaling, the step of using the plurality of DRBs for the single QoS Flow; and A method comprising the step of using a first DRB among the plurality of DRBs for a single QoS flow when the primary DRB among the plurality of DRBs is configured to be used for a single QoS flow through the above RRC signaling.

2. In Claim 1, The above RRC setting includes a threshold value for the buffer related to the first DRB, and If the size of the data stored in the buffer or the size of the data related to the single QoS flow exceeds the threshold value, the step of using the plurality of DRBs for the single QoS Flow; and If the size of the data stored in the buffer or the size of the data related to the single QoS flow is smaller than or equal to the threshold value, the method includes the step of using the first DRB among the plurality of DRBs for the single QoS Flow. A method in which the buffer comprises a buffer of a first PDCP (packet data convergence protocol) entity (210)(280) or an RLC (radio link control) entity (220)(270) associated with the first DRB.

3. In Claim 1, When receiving information from the base station, via the RRC signaling, MAC CE (medium access control control element), or DCI (downlink control information), instructing to use the plurality of DRBs for the single QoS flow, the step of using the plurality of DRBs for the single QoS flow; and A method comprising the step of using the first DRB among the plurality of DRBs for the single QoS flow when receiving information from the base station, via the RRC signaling, the MAC CE, or the DCI, instructing to use the first DRB for the single QoS flow.

4. In Claim 1, A first packet of the single QoS flow is transmitted to the SDAP (service data adaptation protocol) entity (600) by the first PDCP entity (620) associated with the first DRB among the plurality of DRBs, and A second packet of the single QoS flow is transmitted to the SDAP entity (600) by the second PDCP entity (610 or 630) associated with the second DRB among the plurality of DRBs, and Among the data related to the single QoS flow, the order of the second packet precedes the order of the first packet, and A method in which the order of the first packet and the order of the second packet are determined based on a sequence number (SN) for reordering the single QoS flow.

5. In Claim 4, Based on the fact that the first packet is delivered before the second packet is delivered to the SDAP entity (600), a timer for reordering the first packet and the second packet of the single QoS flow is started, and The size of the above timer is set through the above RRC signaling method.

6. In a method performed by a base station in a wireless communication system, A step of receiving a terminal capability information message from a terminal (320); and Based on the terminal capability information message indicating that a Multi-DRB function is supported in which multiple DRBs are available for use for a single QoS (quality of service) flow, the method includes the step (325) of transmitting configuration information for each of the multiple DRBs to the terminal via RRC (radio resource control) signaling. The configuration information for each of the plurality of DRBs above includes a QFI list containing a QoS flow identifier (QFI) of at least one QoS flow that can be used for each DRB, and When the plurality of DRBs are configured to be used for the single QoS flow through the above RRC signaling, the plurality of DRBs are used for the single QoS Flow, and A method in which, when configured to use one primary DRB among the plurality of DRBs for a single QoS flow through the above RRC signaling, the first DRB among the plurality of DRBs is used for the single QoS flow.

7. In Claim 6, The above RRC setting includes a threshold value for the buffer related to the first DRB, and If the size of the data stored in the buffer or the size of the data related to the single QoS flow exceeds the threshold value, the plurality of DRBs are used for the single QoS Flow, and If the size of the data stored in the buffer or the size of the data related to the single QoS flow is smaller than or equal to the threshold value, the first DRB among the plurality of DRBs is used for the single QoS Flow, and A method in which the buffer comprises a buffer of a first PDCP (packet data convergence protocol) entity (210)(280) or an RLC (radio link control) entity (220)(270) associated with the first DRB.

8. In claim 6, the method comprises: The method further includes the step of transmitting information to the terminal instructing it to use the plurality of DRBs for the single QoS flow via the RRC signaling, MAC CE (medium access control control element), or DCI (downlink control information), and wherein the plurality of DRBs are used for the single QoS flow, or A method further comprising the step of transmitting information from the base station, via the RRC signaling, the MAC CE, or the DCI, instructing to use the first DRB for the single QoS flow, wherein the first DRB among the plurality of DRBs is used for the single QoS flow.

9. In Claim 6, A first packet of the single QoS flow is transmitted to the SDAP (service data adaptation protocol) entity (600) by the first PDCP entity (620) associated with the first DRB among the plurality of DRBs, and A second packet of the single QoS flow is transmitted to the SDAP entity (600) by the second PDCP entity (610 or 630) associated with the second DRB among the plurality of DRBs, and Among the data related to the single QoS flow, the order of the second packet precedes the order of the first packet, and A method in which the order of the first packet and the order of the second packet are determined based on a sequence number (SN) for reordering the single QoS flow.

10. In Claim 9, Based on the fact that the first packet is delivered before the second packet is delivered to the SDAP entity (600), a timer for reordering the first packet and the second packet of the single QoS flow is started, and The size of the above timer is set through the above RRC signaling method.

11. In a terminal (user equipment, UE), At least one transceiver; At least one processor communicatively coupled to the above at least one transceiver; and It includes at least one memory that is communicationally coupled to the above at least one processor and stores instructions, and The above instructions are executed individually or in any combination by the above at least one processor, so that the terminal: Transmit a terminal capability information message to the base station, and Based on the fact that the above terminal capability information message indicates that a Multi-DRB function is supported in which multiple DRBs (data radio bearers) are available for a single QoS (quality of service) flow, configuration information for each of the multiple DRBs is received from the base station via RRC (radio resource control) signaling, and the configuration information for each of the multiple DRBs includes a QFI list including a QoS flow identifier (QFI) of at least one QoS flow in which each DRB can be used. When the plurality of DRBs are configured to be used for the single QoS flow through the above RRC signaling, the plurality of DRBs are used for the single QoS Flow; and A terminal that enables the use of a first DRB among the plurality of DRBs for a single QoS flow when configured to use one primary DRB among the plurality of DRBs for a single QoS flow through the above RRC signaling.

12. In Claim 11, The above RRC setting includes a threshold value for the buffer related to the first DRB, and The above commands are the above terminal: If the size of the data stored in the buffer or the size of the data related to the single QoS flow exceeds the threshold value, the plurality of DRBs are used for the single QoS Flow, and If the size of the data stored in the buffer or the size of the data related to the single QoS flow is smaller than or equal to the threshold value, the first DRB among the plurality of DRBs is used for the single QoS Flow, and The above buffer is a terminal that includes a buffer of a first PDCP (packet data convergence protocol) entity (210)(280) or an RLC (radio link control) entity (220)(270) associated with the first DRB.

13. In Claim 11, The above commands are the above terminal: When receiving information from the base station instructing to use the plurality of DRBs for the single QoS flow via the RRC signaling, MAC CE (medium access control control element), or DCI (downlink control information), the plurality of DRBs are used for the single QoS flow, and A terminal that, upon receiving information from the base station, via the RRC signaling, the MAC CE, or the DCI, instructing to use the first DRB for the single QoS flow, uses the first DRB among the plurality of DRBs for the single QoS flow.

14. Regarding base stations, At least one transceiver; At least one processor communicatively coupled to the above at least one transceiver; and It includes at least one memory that is communicationally coupled to the above at least one processor and stores instructions, and The above instructions are executed individually or in any combination by the above at least one processor, so that the base station: Receive a terminal capability information message from the terminal, and Based on the fact that the above terminal capability information message indicates that a Multi-DRB function is supported, in which multiple DRBs (data radio bearers) are available for a single QoS (quality of service) flow, configuration information for each of the multiple DRBs is transmitted to the terminal via RRC (radio resource control) signaling. The configuration information for each of the plurality of DRBs above includes a QFI list containing a QoS flow identifier (QFI) of at least one QoS flow that can be used for each DRB, and When the plurality of DRBs are configured to be used for the single QoS flow through the above RRC signaling, the plurality of DRBs are used for the single QoS Flow, and A base station in which, when configured to use one primary DRB among the plurality of DRBs for a single QoS flow through the above RRC signaling, the first DRB among the plurality of DRBs is used for the single QoS Flow.

15. In Claim 14, The above RRC setting includes a threshold value for the buffer related to the first DRB, and If the size of the data stored in the buffer or the size of the data related to the single QoS flow exceeds the threshold value, the plurality of DRBs are used for the single QoS Flow, and If the size of the data stored in the buffer or the size of the data related to the single QoS flow is smaller than or equal to the threshold value, the first DRB among the plurality of DRBs is used for the single QoS Flow, and The above buffer is a base station that includes a buffer of a first PDCP (packet data convergence protocol) entity (210)(280) or an RLC (radio link control) entity (220)(270) associated with the first DRB.

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