Method and device for processing data in wireless communication system

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting higher data transmission rates. A method for processing control signals in a wireless communication system, of the present disclosure, may be characterized by comprising the steps of: receiving a first control signal transmitted from a base station; processing the received first control signal; and transmitting a second control signal generated on the basis of the processing to the base station.

Description

Method and device for processing data in a wireless communication system

[0001] The present disclosure relates to a wireless communication system or a mobile communication system. Specifically, it relates to a method and device for processing data of the PDCP layer 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 the sub-6GHz frequency band such as 3.5 gigahertz (3.5GHz), but also in the ultra-high frequency band called millimeter wave (mmWave) such as 28GHz and 39GHz ('Above 6GHz'). In addition, for 6G mobile communication technology, which is called the system after 5G communication (Beyond 5G), implementation in the terahertz (THz) band (for example, 3 THz band at 95GHz) is being considered to achieve a transmission speed that is 50 times faster than 5G mobile communication technology and an ultra-low latency time that is reduced to one-tenth.

[0003] In the early stages of 5G mobile communication technology, the goal is to support services and satisfy performance requirements for enhanced Mobile Broadband (eMBB), Ultra-Reliable Low-Latency Communications (URLLC), and massive Machine-Type Communications (mMTC). These include beamforming and massive MIMO to mitigate path loss of radio waves in ultra-high frequency bands and increase the transmission distance of radio waves, support for various numerologies (such as operation of multiple subcarrier intervals) and dynamic operation of slot formats for efficient use of ultra-high frequency resources, initial access technology to support multi-beam transmission and wideband, definition and operation of BWP (Bidth Part), new channel coding methods such as LDPC (Low Density Parity Check) codes for large-capacity data transmission and Polar Code for reliable transmission of control information, and L2 pre-processing (L2). Standardization has been made for network slicing, which provides dedicated networks specialized for specific services, and pre-processing.

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

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

[0006] Once these 5G mobile communication systems are commercialized, an explosive increase in connected devices will be connected to the communication network, necessitating enhanced functionality and performance of 5G mobile communication systems and integrated operation of these connected devices. To this end, new research will be conducted on improving 5G performance and reducing complexity, supporting AI services, supporting metaverse services, and drone communications by utilizing eXtended Reality (XR), Artificial Intelligence (AI), and Machine Learning (ML) to efficiently support Augmented Reality (AR), Virtual Reality (VR), and Mixed Reality (MR).

[0007] In addition, the development of these 5G mobile communication systems includes new waveforms to ensure coverage in the terahertz band of 6G mobile communication technology, multi-antenna transmission technologies such as Full Dimensional MIMO (FD-MIMO), Array Antenna, and Large Scale Antenna, metamaterial-based lenses and antennas to improve the coverage of terahertz band signals, high-dimensional spatial multiplexing technology using Orbital Angular Momentum (OAM), Reconfigurable Intelligent Surface (RIS) technology, as well as full duplex technology to improve the frequency efficiency and system network of 6G mobile communication technology, satellite, AI (Artificial Intelligence) from the design stage and AI-based communication technology that realizes system optimization by internalizing end-to-end AI support functions, and ultra-high-performance communication and computing resources to provide services with complexity that exceeds the limits of terminal computing capabilities. It can serve as a basis for the development of next-generation distributed computing technologies that can be realized by utilizing them.

[0008] The present disclosure provides a method and device for processing data in a wireless communication system or mobile communication system. The technical challenges addressed by the present disclosure are not limited to those mentioned above, and other technical challenges not mentioned will be readily apparent to those skilled in the art, based on the description below.

[0009] According to one embodiment of the present invention, a method for solving the above-described problem is characterized by comprising the steps of: receiving a first control signal transmitted from a base station; processing the received first control signal; generating a second signal based on the processing; and transmitting the generated second control signal to the base station.

[0010] According to embodiments proposed in the present disclosure, a terminal and a base station can process delay-critical data of a PDCP (packet data control protocol) layer and perform a task of calculating the size of delay-critical data of the PDCP layer.

[0011] The effects that can be obtained from the present disclosure are not limited to the effects mentioned above, and other effects that are not mentioned can be clearly understood by a person having ordinary skill in the art to which the present disclosure belongs from the description below.

[0012] FIG. 1 is a diagram illustrating the structure of an NR system according to one embodiment of the present disclosure.

[0013] FIG. 2 is a diagram illustrating a wireless protocol structure in an NR system according to an embodiment of the present disclosure.

[0014] FIG. 3 is a diagram illustrating a procedure in which a base station sets a PDCP duplicate transmission function and / or a Split Bearer function to a PDCP layer using an RRC (radio resource control) message when a terminal establishes a connection with a network according to an embodiment of the present disclosure.

[0015] FIG. 4 is a diagram illustrating an example in which a PDCP layer of a terminal transmits delay-critical data by applying a PDCP redundancy transmission technique according to an embodiment of the present disclosure.

[0016] FIG. 5 is a diagram illustrating an operation of transmitting delay-critical data to a lower layer (RLC (radio link control)) when a specific PDCP layer device of a terminal operates as a Split Bearer, according to an embodiment of the present disclosure.

[0017] FIG. 6 is a diagram illustrating an operation of a PDCP layer device operating as a DAPS Bearer of a terminal according to one embodiment of the present disclosure to process delay-critical data.

[0018] FIG. 7 illustrates the structure of a base station according to one embodiment of the present disclosure.

[0019] Figure 8 illustrates the structure of a terminal according to one embodiment of the present disclosure.

[0020] The operating principles of the present disclosure are described in detail below with reference to the attached drawings. In the following description of the present disclosure, detailed descriptions of related known functions or configurations will be omitted if they are deemed to unnecessarily obscure the gist of the present disclosure. Furthermore, the terms described below are defined based on the functions of the present disclosure and may vary depending on the intent or custom of the user or operator. Therefore, their definitions should be based on the overall content of this specification.

[0021] In describing the embodiments of this disclosure, descriptions of technical details that are well known in the technical field to which this disclosure pertains and are not directly related to this disclosure will be omitted. This is to more clearly convey the gist of this disclosure without obscuring it by omitting unnecessary explanations.

[0022] For the same reason, some components in the attached drawings are exaggerated, omitted, or schematically depicted. Furthermore, the dimensions of each component do not entirely reflect its actual size. Identical or corresponding components in each drawing are assigned the same reference numbers.

[0023] The advantages and features of the present disclosure, and methods for achieving them, will become clearer with reference to the embodiments described below in detail together with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below and may be implemented in various different forms. These embodiments are provided solely to ensure that the present disclosure is 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. Like reference numerals designate like elements throughout the specification.

[0024] At this time, it will be understood that each block of the processing flow diagrams and combinations of the flow diagrams can be performed by computer program instructions. These computer program instructions can be installed in a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing equipment, so that the instructions executed by the processor of the computer or other programmable data processing equipment create a means for performing the functions described in the flow diagram block(s). These computer program instructions can also be stored in a computer-available or computer-readable memory that can direct a computer or other programmable data processing equipment to implement the functions in a specific manner, so that the instructions stored in the computer-available or computer-readable memory can also produce a manufactured item that includes an instruction means for performing the functions described in the flow diagram block(s). Since the computer program instructions may be installed on a computer or other programmable data processing device, a series of operational steps may be performed on the computer or other programmable data processing device to create a computer-executable process, and the instructions that cause the computer or other programmable data processing device to perform the steps for performing the functions described in the flowchart block(s) may also provide steps for performing the functions described in the flowchart block(s).

[0025] Additionally, each block may represent a module, segment, or portion of code that contains one or more executable instructions for performing a specific logical function(s). It should also be noted that in some alternative implementation examples, the functions described in the blocks may occur out of order. For example, two blocks depicted in succession may actually be executed substantially concurrently, or the blocks may sometimes be executed in reverse order, depending on their respective functions.

[0026] Here, the term '~ part' used in the present embodiment means software or hardware components such as FPGA (Field Programmable Gate Array) or ASIC (Application Specific Integrated Circuit), and the '~ part' performs certain roles. However, the '~ part' is not limited to software or hardware. The '~ part' may be configured to be on an addressable storage medium and may be configured to play one or more processors. Therefore, as an example, the '~ part' includes components such as software components, object-oriented software components, class components, and task components, processes, functions, properties, 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'. Additionally, components and '~parts' may be implemented to regenerate one or more CPUs within a device or secure multimedia card.

[0027] Hereinafter, the base station is an entity that performs resource allocation of the terminal, and may be at least one of a Node B, a BS (Base Station), an eNB (eNode B), a gNB (gNode B), a wireless access unit, a base station controller, or a node on a network. The terminal may include a UE (User Equipment), an MS (Mobile Station), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing a communication function. In addition, the embodiments of the present disclosure may be applied to other communication systems having a similar technical background or channel type to the embodiments of the present disclosure described below. In addition, the embodiments of the present disclosure may be applied to other communication systems with some modifications without significantly departing from the scope of the present disclosure at the discretion of a person having skilled technical knowledge. For example, the 5th generation mobile communication technology (5G, new radio, NR) developed after LTE-A may be included here, and the 5G below may also 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 through some modifications within a scope that does not significantly deviate from the scope of the present disclosure, as judged by a person having skilled technical knowledge.

[0028] In the following description, terms used to identify connection nodes, terms referring to network entities or network functions (NFs), terms referring to messages, terms referring to interfaces between network objects, terms referring to various identification information, etc. are provided as examples for convenience of explanation. Therefore, the present disclosure is not limited to the terms described below, and other terms referring to objects having equivalent technical meanings may be used.

[0029] For convenience of explanation below, some terms and names defined in the 3rd generation partnership project (3GPP) LTE (long term evolution) standard and / or 3GPP NR (new radio) standard may be used. However, the present disclosure is not limited to the above terms and names, and can be equally applied to systems conforming to other standards.

[0030] FIG. 1 is a diagram illustrating the structure of an NR system according to one embodiment of the present disclosure.

[0031] Referring to FIG. 1, the wireless communication system may be composed of multiple 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 illustrated in FIG. 1, and may include more or fewer components.

[0032] According to one embodiment of the present disclosure, a user equipment (hereinafter referred to as UE or terminal) (160) can access an external network through base stations (100, 110, 120, 130) and UPF (150).

[0033] In Fig. 1, base stations (100, 110, 120, 130) can serve as access nodes of a cellular network and provide wireless access to terminals accessing the network. For example, base stations (100, 110, 120, 130) can collect status information such as buffer status, available transmission power status, and channel status of terminals to schedule the collected information and support connections between terminals and a core network (CN; in particular, the CN of NR is referred to as 5GC) in order to service user traffic.

[0034] In Fig. 1, gNB (100, 130) can control multiple cells, and an adaptive modulation and coding (AMC) method that determines a modulation scheme and a channel coding rate according to the channel status of the terminal can be applied.

[0035] The core network, which handles various control functions as well as mobility management for terminals, can be connected to multiple base stations. 5GC can also be integrated with existing LTE systems.

[0036] Meanwhile, in a wireless communication system, a user plane (UP) related to transmission of actual user data and a control plane (CP) such as connection management may be configured separately. The gNB (100) and gNB (130) of FIG. 1 may use the UP and CP technologies defined in NR technology, and the ng-eNB (110) and ng-eNB (120), although connected to 5GC, may use the UP and CP technologies defined in LTE (Long Term Evolution) technology.

[0037] AMF (140) is a device that is responsible for various control functions as well as mobility management functions for terminals and can be connected to multiple base stations.

[0038] UPF (150) may refer to a type of gateway device that provides data transmission. Although not illustrated in FIG. 1, the NR wireless communication system may also include a Session Management Function (SMF). The SMF can manage packet data network connections, such as PDU (protocol data unit) sessions provided to terminals.

[0039] FIG. 2 is a diagram illustrating a wireless protocol structure in an NR system according to one embodiment of the present disclosure.

[0040] Referring to FIG. 2, the wireless protocol of the NR system may be composed of an SDAP (Service Data Adaptation Protocol) layer (200)(290), a PDCP (Packet Data Convergence Protocol) layer (210)(280), an RLC (Radio Link Control) layer (220)(270), a MAC (Medium Access Control) layer (230)(260), and a PHY (Physical) layer (240)(250) in the terminal and the base station, respectively.

[0041] The SDAP (Service Data Adaptation Protocol) layer (200)(290) can transmit user data, perform operations for mapping QoS flows to specific DRBs for uplink and downlink, mark QoS flow IDs for uplink and downlink, and map reflective QoS flows to data bearers for uplink SDAP PDUs. SDAP settings corresponding to each DRB can be provided from a higher RRC layer. Of course, the present invention is not limited to the above examples.

[0042] The PDCP (Packet Data Convergence Protocol) layer (210)(280) can be responsible for operations such as IP header compression / decompression. Furthermore, the PDCP layer (210)(280) can provide sequential and out-of-order transmission functions, rearrange the order, duplicate detection, retransmission functions, and encryption and decryption functions. Of course, the present invention is not limited to the above examples.

[0043] The Radio Link Control (RLC) layer (220)(270) can reconfigure PDCP Protocol Data Units (PDUs) into appropriate sizes. Furthermore, the RLC layer (220)(270) can provide sequential and out-of-order transmission functions, and can provide ARQ functions, concatenation, segmentation, reassembly functions, re-segmentation functions, reordering functions, duplicate detection functions, and error detection functions. Of course, the present invention is not limited to the above examples.

[0044] The MAC layer (230)(260) is connected to multiple RLC layer devices configured in a terminal, and can perform operations of multiplexing RLC PDUs into MAC PDUs and demultiplexing RLC PDUs from MAC PDUs. In addition, the MAC layer (230)(260) can provide a mapping function, a scheduling information reporting function, an HARQ function, a priority control function between logical channels, a priority control function between terminals, an MBMS service confirmation function, a transmission format selection function, and a padding function. Of course, the present invention is not limited to the above examples.

[0045] The physical (PHY) layer (240)(250) channels and modulates upper layer data, converts it into OFDM symbols, and transmits it over a wireless channel, or demodulates and channel decodes OFDM symbols received over a wireless channel and transmits them to the upper layer. In addition, the physical layer uses HARQ (Hybrid ARQ) for additional error correction, and the receiver transmits 1 bit whether or not the packet transmitted by the transmitter has been received. This 1 bit information is called HARQ ACK / NACK information.

[0046] Downlink HARQ ACK / NACK information for uplink data transmission is transmitted through the PHICH (Physical Hybrid-ARQ Indicator Channel) physical channel in the case of LTE, and in the case of NR, whether retransmission is necessary or new transmission can be performed can be determined through the UE's scheduling information in the PDCCH (Physical Dedicated Control CHannel), which is a channel through which downlink / uplink resource allocation, etc. are transmitted. This is because NR applies asynchronous HARQ. Uplink HARQ ACK / NACK information for downlink data transmission can be transmitted through the PUCCH (Physical Uplink Control Channel) or PUSCH (Physical Uplink Shared Channel) physical channel. PUCCH is generally transmitted in the uplink of the PCell, which will be described later, but if the UE supports it, the base station may additionally transmit it to the SCell, which will be described later, to the UE, and this is called the PUCCH SCell.

[0047] Although not shown in Figure 2, an RRC (Radio Resource Control) layer exists above the PDCP layer of each terminal and base station, and the RRC layer can transmit and receive connection and measurement-related setting control messages for radio resource control.

[0048] Meanwhile, the physical layer can be composed of one or more frequencies / carriers, and the technology that sets and uses multiple frequencies simultaneously is called carrier aggregation (CA). CA technology can dramatically increase the transmission capacity by using the primary carrier and one or more secondary carriers in addition to a single carrier for communication between a terminal (or User Equipment, UE) and a base station (eNB or gNB). Meanwhile, in LTE / NR, a cell within a base station that uses a primary 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).

[0049] In this disclosure, a method for transmitting delay-critical packets using PDCP duplication or split bearer technology is proposed when multiple RLC layer devices are associated with a PDCP layer device, considering a terminal configured with CA or dual connectivity (DC) technology. The proposed method is specified in this disclosure using the following terminology.

[0050] - Pcell (Primary Cell): This refers to the serving cell used when the terminal first establishes a connection with the base station, and the connection is established by transmitting and receiving major RRC messages using the Pcell. In addition, the Pcell always has PUCCH transmission resources and can indicate HARQ ACK or NACK, and both uplink and downlink are always configured, and can be used as a reference cell for timing adjustment (Timing Advance, pTAG (Primary Timing Advance Group)). For example, if frequency aggregation technology is configured after the Pcell is configured and an Scell ​​is added, the Scell ​​can perform uplink data transmission by referring to the timing adjustment value of the Pcell. In addition, if dual access technology is configured, the Pcell refers to the PCell of the MCG (Master Cell Group).

[0051] - MCG (Master Cell Group): Refers to the serving cell where the terminal first establishes a connection with the base station or a group of cells supported by the base station. When dual access technology is set, major RRC messages are transmitted or received through the MCG.

[0052] - SCG (Secondary Cell Group): A terminal can establish a connection with a base station and add cells from other base stations in addition to the MCG. This refers to a group of cells supported by other base stations. When dual access technology is set, it can be added to increase additional data transmission rates or efficiently support terminal mobility.

[0053] - PScell ​​(Primary Secondary Cell): When a terminal establishes a connection with a base station and a group of cells from other base stations is added in addition to the MCG and dual access technology is set, the cell corresponding to the Pcell in the SCG is called a PScell.

[0054] - Scell ​​(Secondary Cell): The cells additionally set by the base station to set up carrier aggregation technology after the terminal establishes the initial connection with the base station are called Scells. The SCell may have PUCCH transmission resources depending on the base station settings, and uplink or downlink may be set depending on the base station settings. Also, it may be used as a reference cell for timing adjustment (Timing Advance, sTAG (Secondary Timing Advance Group)) depending on the base station settings. For example, if a Pcell is set and then frequency aggregation technology is set, Scells are added and an sTAG is set, other Scells of the sTAG can perform uplink data transmission by referencing the timing adjustment value of the designated Scell. In addition, if dual access technology is set for the terminal, the Scell ​​refers to Scells excluding the PCell of the MCG (Master Cell Group) or Scells excluding the PScell ​​of the SCG (Secondary Cell Group).

[0055] - Primary RLC layer device (Primary RLC entity): When the PDCP redundancy function is set, multiple RLC layer devices can be set up in one PDCP layer device, and one RLC layer device that is not deactivated and is always used among the multiple RLC layer devices can be called the Primary RLC layer device. In addition, the PDCP layer device can be characterized in that the PDCP Control PDU is not transmitted redundantly and is always transmitted to the Primary RLC layer device. When the PDCP measuring device is associated with two or more RLC measuring devices, the Primary RLC measuring device can be set up by the upper layer (RRC).

[0056] - Split Bearer: In a dual connection situation, this can refer to a bearer that can use the radio resources of both MCG / MgNB and SCG / SgNB.

[0057] - DAPS Bearer: During DAPS Handover, this can refer to a bearer that can use the radio resources of both the source base station and the target base station.

[0058] - Split Secondary RLC layer device (Split RLC entity): In a dual connectivity situation, this can refer to an RLC layer device other than the Primary RLC layer device associated with the Split Bearer. If the PDCP layer device is associated with two RLC layer devices, the Split Secondary RLC layer device can refer to one of the two associated RLC layer devices other than the Primary RLC layer device. If the PDCP layer device is associated with more than two RLC layer devices, the Split Secondary RLC layer device can be configured by a higher layer (RRC).

[0059] - Delay-critical PDCP SDU: If pdu-SetDiscard is not set, this may refer to a PDCP SDU whose remaining time before discardTimer expires is shorter than remainingTimeThreshold. If pdu-SetDiscard is set, this may refer to a PDCP SDU belonging to a PDU Set that includes at least one PDCP SDU whose remaining time before discardTimer expires is shorter than remainingTimeThreshold. The remainingTimeThreshold can be set by the base station for each Cell Group / MAC layer device and for each LCG (Logical Channel Group) of the Cell Group / MAC layer device through an RRC message (RRCSetup, RRCReconfiguration). Therefore, among the data in the PDCP layer device, a delay-critical PDCP SDU for a specific Cell Group / MAC layer device can be determined based on the remainingTimeThreshold of the corresponding LCG of the Cell Group / MAC layer device.

[0060] - PDU Set: It may consist of one or more PDUs corresponding to the payload of one unit of information generated by the application (see TS 23.501). One PDU belonging to the PDU Set can be regarded as one PDCP SDU.

[0061] - Delay-Critical PDCP Data Volume: For the Delay Status Report (DSR) reported in the MAC layer, the transmitting PDCP layer device of the terminal may include all or part of the following Delay-Critical Data-1 to Delay-Critical Data-5 when determining the Delay-Critical PDCP Data Volume.

[0062] ● Delay-critical Data-1: The delay-critical PDCP SDUs for which no PDCP Data PDUs have been constructed

[0063] ● Delay-critical Data-2: PDCP Data PDUs that contain the delay-critical PDCP SDUs and have not been submitted to lower layers (RLC)

[0064] ● Delay-critical data-3: PDCP Control PDUs

[0065] ● Delay Critical Data-4: For AM DRBs, the PDCP SDUs to be retransmitted according to clause 5.1.2 and clause 5.13 of TS 38.323

[0066] ● Delay Critical Data-5: For AM DRBs, the PDCP Data PDUs to be retransmitted according to clause 5.5 of TS 38.323

[0067] - DSR-supporting RLC layer device: This may refer to an RLC layer device associated with the RLC layer device and a MAC layer device supporting DSR. For example, the RLC layer device and the MAC layer device associated with the RLC layer device may be a NR RLC layer device and a NR MAC layer device, respectively, that support DSR.

[0068] According to one embodiment of the present disclosure, in a PDCP layer device of a terminal, if a specific PDCP SDU becomes a delay-critical PDCP SDU and a PDCP Data PDU including the PDCP SDU has already been delivered to a lower layer (e.g., RLC) of the terminal, a delay-critical indication for the PDCP Data PDU can be provided to a lower layer (e.g., RLC) of the terminal through internal signaling.

[0069] FIG. 3 is a diagram illustrating a procedure in which a base station sets a PDCP duplicate transmission function and / or a Split Bearer function in a PDCP layer using an RRC message when a terminal establishes a connection with a network according to an embodiment of the present disclosure.

[0070] Figure 3 illustrates a procedure in which a terminal establishes a connection with a network by switching from RRC idle mode (RRC_IDLE) to RRC connected mode (RRC_CONNECTED) in the present disclosure. In Figure 3, the terminal establishes uplink / downlink transmission synchronization with a base station through a random access process and transmits an RRCSetupRequest message to the base station (300). The RRCSetupRequest message may include an identifier of the terminal and a reason for establishing a connection (EstablishmentCause). The base station may transmit an RRCSetup message to the terminal to establish an RRC connection (305).

[0071] According to one embodiment of the present disclosure, the RRCSetup message may include configuration information (RadioBearerConfig) for each Radio Bearer (DRB or SRB). The Radio Bearer configuration information may include an ID of each Radio Bearer, configuration information (PDCP-Config) for the PDCP layer device of the Radio Bearer, and an indicator indicating whether the Radio Bearer is a DAPS Bearer. For example, the PDCP-Config may include the following configuration information.

[0072] - discardTimer: You can set the size of the discardTimer to be applied to PDCP SDUs in the PDCP layer device of the corresponding bearer.

[0073] - If there are two or more RLC layer devices associated / connected with the corresponding PDCP layer device:

[0074] ● Primary RLC layer device indicator (primaryPath): For example, the primary RLC layer device can be configured through an indicator that indicates the Cell Group (CellGroupId) to which the RLC layer device belongs and the Logical Channel (LogicalChannelIdentity) corresponding to the RLC layer device in the Cell Group.

[0075] ● Uplink Split Bearer Threshold (UL-DataSplitThreshold): You can set a threshold that can be used in Split Bearer. When operating as Split Bearer, if the amount of data to be transmitted is less than the threshold, data is transmitted only to the Primary RLC layer device. If the amount of data to be transmitted is greater than the threshold, data can be transmitted to the Primary RLC layer device and Split Secondary RLC layer device.

[0076] ● PDCP-Duplication: When receiving the RRC message / IE, it can indicate whether the PDCP duplication transmission function of the corresponding PDCP layer device is set and activated. The field can be BOOLEAN indicating TRUE or FALSE. When the field exists, the corresponding PDCP layer device can consider that the duplication transmission function is set. For example, the PDCP duplication transmission function may not be set for a CA-based LTE RLC Bearer. The setting value of the field can indicate whether the initial state of the PDCP duplication transmission function is activated or deactivated when the terminal receives the RRC message / IE. For example, if the setting value is TRUE, it can start in an activated state, and if it is FALSE, it can start in a deactivated state. For example, when the field is set for an SRB, the setting value can be specified to always be set to TRUE. If there are three or more RLC layer devices associated with the corresponding PDCP layer device (moreThanTwoRLC-DRB is present), the above field may always be present, and the terminal ignores the setting value of the above field, and the initial state of activation / deactivation of the duplication transmission function of the RLC layer devices (other than the Primary RLC layer device) associated with the corresponding PDCP layer device may be configured through the duplicationState field. For example, the duplication transmission function in which three or more RLC layer devices (more than two associated RLC entities) are associated with the PDCP layer device may be supported only for NR RLC layer devices (NR RLC Bearer).

[0077] ● If there are three or more RLC layer devices associated / connected with the corresponding PDCP layer device:

[0078] * Split Secondary RLC layer device indicator (splitSecondaryPath): It may include an indicator indicating a Split Secondary RLC layer device. For example, the base station may indicate the Split Secondary RLC layer device by indicating the LCID (Logical Channel ID) corresponding to the Split Secondary RLC layer device. For example, the Split Secondary RLC layer indicator may be used for the purpose of indicating the Split Secondary RLC layer device when the PDCP layer device falls back to the Split Bearer and operates when there are three or more RLC layer devices associated with the PDCP layer device. For example, the Split Secondary RLC layer device indicator may only specify the LCID corresponding to the RLC layer device, and may not specify the Cell Group to which the RLC layer device belongs. This may be set so that the Cell Group to which the RLC layer device belongs may be designated as a Cell Group other than the Cell Group to which the Primary RLC layer device belongs among MCG and SCG. If there are two RLC layer devices associated with the PDCP layer device, the Split Secondary RLC layer device indicator may not be required. For example, since the Primary RLC layer device can be configured via the Primary RLC layer device indicator, one other RLC layer device, excluding the Primary RLC layer device, can be designated as the Split Secondary RLC layer device even without the Split Secondary RLC layer device indicator.

[0079] * duplicationState: This field indicates the initial activation / deactivation status of the duplication transmission function for each RLC layer device associated with the corresponding PDCP layer device when the terminal receives the corresponding RRC message / IE. For example, the field can contain three BOOLEAN settings, and each BOOLEAN setting value can correspond to a specific RLC layer device. If the setting value of the field is set to TRUE, the initial activation status can be indicated for the corresponding RLC layer device, and if it is set to FALSE, the initial deactivation status can be indicated. The determination method for each RLC layer device corresponding to the three BOOLEAN setting values ​​can be such that among the RLC layer devices associated with the corresponding PDCP layer device, excluding the Primary RLC layer device, in the order of MCG to SCG, and in the ascending order of LCID (Logical Channel ID), there can be a mapping relationship between the RLC layer devices and the BOOLEAN setting values. If there are two RLC layer devices associated with the PDCP layer device, excluding the Primary RLC layer device, the terminal may ignore the BOOLEAN setting with the highest index value. If this field does not exist, the PDCP redundant transmission function may be considered disabled for all associated RLC layer devices.

[0080] Referring to Fig. 3, a terminal that has established an RRC connection enters RRC_CONNECTED mode and transmits an RRCSetupComplete message to the base station (310). If the base station does not know the terminal capabilities of the terminal that is currently establishing a connection or wants to determine the terminal capabilities, it can send a message to the terminal asking about the terminal capabilities (315). Then, the terminal can send a message reporting its capabilities to the base station (320). The message can indicate whether the terminal supports the PDCP duplicate transmission / Split Bearer function and can be sent including an indicator indicating this.

[0081] To set up security with a terminal, the base station may transmit a SecurityModeCommand message (325) to the terminal, and the terminal may transmit a SecurityModeComplete message (330) to the base station. Once the security setting is complete, the base station may transmit an RRCReconfiguration message to the terminal (335).

[0082] For example, the above message (RRCReconfiguration) may include configuration information (RadioBearerConfig) for each Radio Bearer (DRB or SRB). The Radio Bearer configuration information may include the ID of each Radio Bearer, configuration information (PDCP-Config) for the PDCP layer device of the Radio Bearer, and an indicator indicating whether the Radio Bearer is a DAPS Bearer. For example, the PDCP-Config may include the following configuration information.

[0083] - discardTimer: You can set the size of the discardTimer to be applied to PDCP SDUs in the PDCP layer device of the corresponding bearer.

[0084] - If there are two or more RLC layer devices associated / connected with the corresponding PDCP layer device:

[0085] ● Primary RLC layer device indicator (primaryPath): For example, the primary RLC layer device can be configured through an indicator that indicates the Cell Group (CellGroupId) to which the RLC layer device belongs and the Logical Channel (LogicalChannelIdentity) corresponding to the RLC layer device in the Cell Group.

[0086] ● Uplink Split Bearer Threshold (UL-DataSplitThreshold): You can set a threshold that can be used in Split Bearer. When operating as Split Bearer, if the amount of data to be transmitted is less than the threshold, data is transmitted only to the Primary RLC layer device. If the amount of data to be transmitted is greater than the threshold, data can be transmitted to the Primary RLC layer device and Split Secondary RLC layer device.

[0087] ● pdcp-Duplication: When receiving the RRC message / IE, it can indicate whether the PDCP duplicate transmission function of the corresponding PDCP layer device is set and activated. The field can be BOOLEAN indicating TRUE or FALSE. When the field exists, the corresponding PDCP layer device can consider that the duplicate transmission function is set. For example, the PDCP duplicate transmission function may not be set for a CA-based LTE RLC Bearer. The setting value of the field can indicate whether the initial state of the PDCP duplicate transmission function is activated or deactivated when the terminal receives the RRC message / IE. For example, if the setting value is TRUE, it can start in the activated state, and if it is FALSE, it can start in the deactivated state. For example, when the field is set for SRB, the setting value can be specified to always be set to TRUE. If there are three or more RLC layer devices associated with the corresponding PDCP layer device (moreThanTwoRLC-DRB is present), the above field may always be present, and the terminal ignores the setting value of the above field, and the initial state of activation / deactivation of the duplication transmission function of the RLC layer devices (other than the Primary RLC layer device) associated with the corresponding PDCP layer device may be configured through the duplicationState field. For example, the duplication transmission function in which three or more RLC layer devices (more than two associated RLC entities) are associated with the PDCP layer device may be supported only for NR RLC layer devices (NR RLC Bearer).

[0088] ● If there are three or more RLC layer devices associated / connected with the corresponding PDCP layer device:

[0089] * Split Secondary RLC layer device indicator (splitSecondaryPath): It may include an indicator indicating a Split Secondary RLC layer device. For example, the base station may indicate the Split Secondary RLC layer device by indicating the LCID (Logical Channel ID) corresponding to the Split Secondary RLC layer device. For example, the Split Secondary RLC layer indicator may be used for the purpose of indicating the Split Secondary RLC layer device when the PDCP layer device falls back to the Split Bearer and operates when there are three or more RLC layer devices associated with the PDCP layer device. For example, the Split Secondary RLC layer device indicator may only specify the LCID corresponding to the RLC layer device, and may not specify the Cell Group to which the RLC layer device belongs. This may be set so that the Cell Group to which the RLC layer device belongs may be designated as a Cell Group other than the Cell Group to which the Primary RLC layer device belongs among MCG and SCG. If there are two RLC layer devices associated with the PDCP layer device, the Split Secondary RLC layer device indicator may not be required. For example, since the Primary RLC layer device can be configured via the Primary RLC layer device indicator, one other RLC layer device, excluding the Primary RLC layer device, can be designated as the Split Secondary RLC layer device even without the Split Secondary RLC layer device indicator.

[0090] * duplicationState: This field indicates the initial activation / deactivation status of the duplication transmission function for each RLC layer device associated with the corresponding PDCP layer device when the terminal receives the corresponding RRC message / IE. For example, the field can contain three BOOLEAN settings, and each BOOLEAN setting value can correspond to a specific RLC layer device. If the setting value of the field is set to TRUE, the initial activation status can be indicated for the corresponding RLC layer device, and if it is set to FALSE, the initial deactivation status can be indicated. The determination method for each RLC layer device corresponding to the three BOOLEAN setting values ​​can be such that among the RLC layer devices associated with the corresponding PDCP layer device, excluding the Primary RLC layer device, in the order of MCG to SCG, and in the ascending order of LCID (Logical Channel ID), there can be a mapping relationship between the RLC layer devices and the BOOLEAN setting values. If there are two RLC layer devices associated with the PDCP layer device, excluding the Primary RLC layer device, the terminal may ignore the BOOLEAN setting with the highest index value. If this field does not exist, the PDCP redundant transmission function may be considered disabled for all associated RLC layer devices.

[0091] For example, the above message (RRCReconfiguration) may include RLC Bearer configuration information (RLC-BearerConfig) for each Cell Group (MCG, SCG) belonging to the corresponding Cell Group. The RLC Bearer configuration information may include the following information.

[0092] - logicalChannelIdentity: You can indicate the LCID corresponding to the RLC Bearer / layer device.

[0093] - servedRadioBearer: Indicates the Radio Bearer ID associated with the RLC Bearer / layer device. The Radio Bearer ID may indicate a specific DRB or SRB.

[0094] - rlc-Config: You can indicate the RLC layer parameter setting information of the RLC layer device of the corresponding RLC Bearer.

[0095] When RRC (re)configuration is completed, the terminal can transmit an RRCReconfigurationComplete message to the base station (340). The terminal and the base station can perform a data transmission procedure (345). At this time, a typical data transmission process can be largely composed of three steps: RRC connection setup, security setup, and DRB setup. In addition, the base station can transmit an RRCReconfiguration message to the terminal to update, add, or change settings for a given reason (at least one of 335 or 350).

[0096] According to one embodiment of the present disclosure, the RRCReconfiguration message may include configuration information (RadioBearerConfig) for each Radio Bearer (DRB or SRB). The Radio Bearer configuration information may include an ID of each Radio Bearer, configuration information (PDCP-Config) for the PDCP layer device of the Radio Bearer, and an indicator indicating whether the Radio Bearer is a DAPS Bearer. For example, the PDCP-Config may include the following configuration information.

[0097] - discardTimer: You can set the size of the discardTimer to be applied to PDCP SDUs in the PDCP layer device of the corresponding bearer.

[0098] - If there are two or more RLC layer devices associated / connected with the corresponding PDCP layer device:

[0099] ● Primary RLC layer device indicator (primaryPath): For example, the primary RLC layer device can be configured through an indicator that indicates the Cell Group (CellGroupId) to which the RLC layer device belongs and the Logical Channel (LogicalChannelIdentity) corresponding to the RLC layer device in the Cell Group.

[0100] ● Uplink Split Bearer Threshold (UL-DataSplitThreshold): You can set a threshold that can be used in Split Bearer. When operating as Split Bearer, if the amount of data to be transmitted is less than the threshold, data is transmitted only to the Primary RLC layer device. If the amount of data to be transmitted is greater than the threshold, data can be transmitted to the Primary RLC layer device and Split Secondary RLC layer device.

[0101] ● pdcp-Duplication: When receiving the RRC message / IE, it may indicate whether the PDCP duplicate transmission function of the corresponding PDCP layer device is set and activated. The field may be BOOLEAN indicating TRUE or FALSE. When the field exists, the corresponding PDCP layer device may consider that the duplicate transmission function is set. In one example, the PDCP duplicate transmission function may not be set for a CA-based LTE RLC Bearer. The setting value of the field may indicate whether the initial state of the PDCP duplicate transmission function is activated or deactivated when the terminal receives the RRC message / IE. For example, if the setting value is TRUE, it may start in an activated state, and if it is FALSE, it may start in a deactivated state. For example, when the field is set for an SRB, the setting value may be specified to always be set to TRUE. If there are three or more RLC layer devices associated with the corresponding PDCP layer device (moreThanTwoRLC-DRB is present), the above field may always be present, and the terminal ignores the setting value of the above field, and the initial state of activation / deactivation of the duplication transmission function of the RLC layer devices (other than the Primary RLC layer device) associated with the corresponding PDCP layer device may be configured through the duplicationState field. For example, the duplication transmission function in which three or more RLC layer devices (more than two associated RLC entities) are associated with the PDCP layer device may be supported only for NR RLC layer devices (NR RLC Bearer).

[0102] ● If there are three or more RLC layer devices associated / connected with the corresponding PDCP layer device:

[0103] * Split Secondary RLC layer device indicator (splitSecondaryPath): It may include an indicator indicating a Split Secondary RLC layer device. For example, the base station may indicate the Split Secondary RLC layer device by indicating the LCID (Logical Channel ID) corresponding to the Split Secondary RLC layer device. For example, the Split Secondary RLC layer indicator may be used for the purpose of indicating the Split Secondary RLC layer device when the PDCP layer device falls back to the Split Bearer and operates when there are three or more RLC layer devices associated with the PDCP layer device. For example, the Split Secondary RLC layer device indicator may only specify the LCID corresponding to the RLC layer device, and may not specify the Cell Group to which the RLC layer device belongs. This may be set so that the Cell Group to which the RLC layer device belongs may be designated as a Cell Group other than the Cell Group to which the Primary RLC layer device belongs among MCG and SCG. If there are two RLC layer devices associated with the PDCP layer device, the Split Secondary RLC layer device indicator may not be required. For example, since the Primary RLC layer device can be configured via the Primary RLC layer device indicator, one other RLC layer device, excluding the Primary RLC layer device, can be designated as the Split Secondary RLC layer device even without the Split Secondary RLC layer device indicator.

[0104] * duplicationState: This field indicates the initial activation / deactivation status of the duplication transmission function for each RLC layer device associated with the corresponding PDCP layer device when the terminal receives the corresponding RRC message / IE. For example, the field can contain three BOOLEAN settings, and each BOOLEAN setting value can correspond to a specific RLC layer device. If the setting value of the field is set to TRUE, the initial activation status can be indicated for the corresponding RLC layer device, and if it is set to FALSE, the initial deactivation status can be indicated. The determination method for each RLC layer device corresponding to the three BOOLEAN setting values ​​can be such that among the RLC layer devices associated with the corresponding PDCP layer device, excluding the Primary RLC layer device, in the order of MCG to SCG, and in the ascending order of LCID (Logical Channel ID), there can be a mapping relationship between the RLC layer devices and the BOOLEAN setting values. If there are two RLC layer devices associated with the PDCP layer device, excluding the Primary RLC layer device, the terminal may ignore the BOOLEAN setting with the highest index value. If this field does not exist, the PDCP redundant transmission function may be considered disabled for all associated RLC layer devices.

[0105] According to one embodiment of the present disclosure, the RRCReconfiguration message may include, for each Cell Group (MCG, SCG), RLC Bearer configuration information (RLC-BearerConfig) belonging to the corresponding Cell Group. The RLC Bearer configuration information may include the following information.

[0106] - logicalChannelIdentity: Indicates the LCID corresponding to the RLC Bearer / layer device.

[0107] - servedRadioBearer: This can indicate a Radio Bearer ID associated with the corresponding RLC Bearer / layer device. The Radio Bearer ID can indicate a specific DRB or SRB.

[0108] - RLC-Config: You can indicate the RLC layer parameter setting information of the RLC layer device of the corresponding RLC Bearer.

[0109] In one embodiment of the present disclosure, upon receiving an RRC message (RRCReconfiguration), each Radio Bearer is set up by the Radio Bearer setting of the corresponding message, a corresponding PDCP layer device is set up, and an RLC Bearer / layer device having an association with each Radio Bearer / PDCP layer device is set up, and then an association between the RLC layer device and the PDCP layer device can be established. For example, one Radio Bearer corresponds to one PDCP layer device. For example, each PDCP layer device can be associated with one, two, three, four, six, or eight RLC layer devices as follows.

[0110] - A PDCP layer device of a Split Bearer can be associated with two uplink or two downlink UM RLC layer devices, four UM RLC layer devices (two downlink and two uplink), or two AM RLC layer devices.

[0111] - An RB with PDCP redundancy transmission enabled can be associated with N UM RLC layer devices (all downlink or all uplink), 2 × N UM RLC layer devices (N uplink and N downlink), or N AM RLC layer devices, where N can be greater than or equal to 2 and less than or equal to 4.

[0112] - A PDCP layer device of a DAPS Bearer can be associated with two UM RLC layer devices (both uplink or both downlink, one for the Source cell and one for the Target cell), four UM RLC layer devices (uplink and downlink of the Source cell, uplink and downlink of the Target cell), or two AM RLC layer devices (one for the Source cell and one for the Target cell).

[0113] - In other cases, each PDCP layer device may be associated with one UM RLC layer device, two UM RLC layer devices (one each for uplink and downlink), or one AM RLC layer device.

[0114] In one embodiment of the present disclosure, the transmitting unit of the PDCP layer device of the terminal for which the pdcp-Duplication is set can operate as follows.

[0115] - About SRB:

[0116] ● PDCP duplicate transmission function can be activated.

[0117] - About DRB:

[0118] ● If an activation instruction for the PDCP redundant transmission feature is received (via RRC or MAC CE) for the given DRB:

[0119] * PDCP duplicate transmission function can be activated for the corresponding DRB.

[0120] ● If PDCP redundant transmission feature is enabled (via RRC or MAC CE) for at least one associated RLC layer device:

[0121] * PDCP redundant transmission feature can be enabled for the indicated RLC layer device.

[0122] * Activation of PDCP redundant transmission function can be performed for the corresponding DRB.

[0123] ● If an instruction to disable PDCP duplicate transmission function is received (via RRC or MAC CE) for the DRB in question:

[0124] * For the DRB in question, PDCP duplicate transmission function can be disabled.

[0125] ● If, for at least one associated RLC layer device, a PDCP duplicate transmission feature disablement instruction is received (via RRC or MAC CE):

[0126] * For the associated RLC layer device that received the instruction, PDCP duplicate transmission function can be disabled.

[0127] * If PDCP redundant transmission feature is disabled for all associated RLC layer devices except the Primary RLC layer device:

[0128] - PDCP duplicate transmission function can be disabled for the corresponding DRB.

[0129] According to one embodiment of the present disclosure, when the PDCP redundancy transmission function is set for one or more DRBs, the base station can instruct, through MAC CE, to activate / deactivate the PDCP redundancy transmission function of all or some of the associated RLC layer devices for the DRBs for which the PDCP redundancy transmission function is set.

[0130] In one example, in the case below, the terminal can activate or deactivate the PDCP redundant transmission function for the DRB for which the function is configured.

[0131] - When an activation / deactivation indication is received from the base station via the Duplication Activation / Deactivation MAC CE of TS 38.321 section 6.1.3.11. For example, the Duplication Activation / Deactivation MAC CE can indicate activation / deactivation of the PDCP duplicate transmission function only when the number of associated RLC layer devices is two.

[0132] - When an activation / deactivation indication is received from the base station via the Duplication RLC Activation / Deactivation MAC CE of TS 38.321 section 6.1.3.32.

[0133] - When an activation / deactivation instruction (e.g., pdcp-Duplication, duplicationState) is received from the base station through an RRC message

[0134] In one example, in the case below, the terminal can enable / disable the PDCP redundant transmission function for all or some RLC layer devices associated with the DRB for which the function is enabled.

[0135] - When an activation / deactivation indication is received from the base station via the Duplication RLC Activation / Deactivation MAC CE of TS 38.321 section 6.1.3.32.

[0136] - When an activation / deactivation instruction (e.g., pdcp-Duplication, duplicationState) is received from the base station through an RRC message

[0137] In one example, a terminal may enable the PDCP redundant transmission feature for all associated RLC layer devices for the DRB for which the feature is configured, in the following cases:

[0138] - When receiving an Uplink Grant, which is specified by CS-RNTI and has NDI (New Data Indicator) = 1, for a Logical Channel associated with a DRB with survivalTimeStateSupport set.

[0139] In one embodiment of the present disclosure, a MAC layer device of a terminal may operate as follows for each DRB for which a PDCP redundant transmission function is set.

[0140] - When an instruction to activate the PDCP duplicate transmission function for a specific DRB is received via Duplication Activation / Deactivation MAC CE:

[0141] ● It is possible to instruct the upper layer (PDCP) to activate the PDCP redundant transmission function for the corresponding DRB.

[0142] - When an instruction to disable PDCP duplicate transmission functionality for a specific DRB is received via Duplication Activation / Deactivation MAC CE:

[0143] ● It is possible to instruct the upper layer (PDCP) to disable the PDCP duplicate transmission function for the corresponding DRB.

[0144] - When an indication to activate the PDCP duplicate transmission feature for a specific DRB is received via a Duplication RLC Activation / Deactivation MAC CE for one or more Secondary RLC layer devices associated with that DRB:

[0145] ● It can instruct the upper layer (PDCP) to enable PDCP redundant transmission function for one or more secondary RLC layer devices.

[0146] - When an instruction to disable PDCP duplicate transmission functionality for a specific DRB is received via Duplication RLC Activation / Deactivation MAC CE for one or more Secondary RLC layer devices associated with that DRB:

[0147] ● It is possible to instruct the upper layer (PDCP) to disable the PDCP redundant transmission function for one or more Secondary RLC layer devices.

[0148] - For a Logical Channel associated with a DRB with survivalTimeStateSupport set, when receiving an Uplink Grant specified by CS-RNTI and with New Data Indicator (NDI) = 1:

[0149] ● It can instruct the upper layer (PDCP) to enable PDCP redundant transmission function for all associated RLC layer devices of the DRB.

[0150] According to one embodiment of the present disclosure, in a DC situation, in a situation where both Cell Groups (MCG, SCG) support DSR, among PDCP SDUs and PDCP PDUs buffered in a PDCP layer device operating as a Split Bearer, the criteria for determining delay-critical data-1 and delay-critical data-2 may be one of the following options.

[0151] Option 1: If the MAC layer device of the MCG is Delay Critical Data-1 or Delay Critical Data-2 (based on the remainingTimeThreshold of the corresponding LCG of the MCG MAC), then the corresponding PDCP SDU / PDU can be Delay Critical Data-1 or Delay Critical Data-2 of the corresponding PDCP layer device.

[0152] Option 2: If the SCG's MAC layer device criteria (based on the remainingTimeThreshold of the corresponding LCG of the SCG MAC) is delay-critical data-1 or delay-critical data-2, then the corresponding PDCP SDU / PDU can be delay-critical data-1 or delay-critical data-2 of the corresponding PDCP layer device.

[0153] Option 3: If at least one of the MAC layer device criteria of the SCG or MCG (or the smaller remainingTimeThreshold value of the two thresholds) is delay-critical data-1 or delay-critical data-2, then the corresponding PDCP SDU / PDU may be delay-critical data-1 or delay-critical data-2 for the corresponding PDCP layer device.

[0154] Option 4: If the Cell Group to which the Primary RLC layer device belongs or the MAC layer device associated with the Primary RLC layer device (based on the remainingTimeThreshold of the corresponding LCG of the corresponding MAC) is Delay Critical Data-1 or Delay Critical Data-2, then the corresponding PDCP SDU / PDU may be Delay Critical Data-1 or Delay Critical Data-2 for the corresponding PDCP layer device.

[0155] Option 5: If Delay Critical Primary RLC layer device is configured, then the PDCP SDU / PDU can be Delay Critical Data-1 or Delay Critical Data-2 for that PDCP layer device, based on the Cell Group to which that RLC layer device belongs or the MAC layer device associated with that RLC layer device (based on the remainingTimeThreshold of that LCG of that MAC).

[0156] Option 6: The base station can indicate via RRC messages (RRCSetup, RRCReconfiguration) which Cell Group / MAC layer device should determine delay-critical data-1 / 2 based on the remainingTimeThreshold of the corresponding LCG.

[0157] FIG. 4 is a diagram illustrating an example in which a PDCP layer of a terminal transmits delay-critical data by applying a PDCP redundancy transmission technique according to an embodiment of the present disclosure.

[0158] According to one embodiment of the present disclosure, when data with a remaining time less than a specific threshold (remainingTimeThreshold) until the expiration of the discardTimer occurs in the PDCP and RLC buffers, the MAC layer device of the terminal may report the size of the data and the remaining time (RemainingTime) to the base station through a Delay Status Report (DSR) MAC CE. For example, the DSR may be triggered when the following conditions are met.

[0159] - DSR trigger condition: In an LCG (Logical Channel Group) where DSR is set, if the remaining time of the discardTimer of the data with the shortest remaining time of the PDCP discardTimer among the data in the buffer of the LCG that has not yet been transmitted via MAC PDU and whose data size has not yet been reported via DSR becomes shorter than the remainingTimeThreshold of the LCG, and if there is no DSR pending in the LCG (after the last DSR MAC CE transmission), DSR can be triggered for the LCG.

[0160] A DSR MAC CE may contain the following fields:

[0161] - LCGi: It can indicate the presence or absence of the Remaining Time and Buffer Size fields corresponding to LCG i. If set to 1, it can indicate the presence of the field, and if set to 0, it can indicate the absence of the field.

[0162] - Remaining Time: For each LCG, the remaining time of the PDCP SDU with the shortest discardTimer remaining time can be indicated based on the first symbol time of the PUSCH transmission including the DSR MAC CE among the PDCP SDUs buffered in the LCG.

[0163] - BT: This field can only be present for LCGs that have additionalBSR-TableAllowed set. If this field is present, its setting (0 or 1) can be used as an indicator of the Buffer Size Table, indicating which Buffer Size Table was used to set the Buffer Size field of the LCG in the DSR MAC CE.

[0164] - Buffer Size: After the MAC PDU including the corresponding DSR MAC CE is created, for each LCG, the total size of the delay-critical uplink data (Delay-Critical UL Data) determined by the data volume calculation procedure of the RLC (TS 38.322) and PDCP (38.323) layer devices associated with the corresponding MAC layer device among the data in the buffer can be indicated.

[0165] To determine the total size of the delay-critical UL data indicated by the Buffer Size field of the DSR MAC CE, each RLC and PDCP layer device of the terminal associated with the MAC layer device of the terminal may indicate the size of the delay-critical UL data to the corresponding MAC layer device.

[0166] Referring to FIG. 4, a specific PDCP layer device of a terminal (400) may have an association with one or more RLC layer devices.

[0167] In one embodiment of the present disclosure, the base station may provide PDCP settings dedicated to delay-critical data through PDCP settings (PDCP-Config) of a specific bearer of the terminal via the RRC message (RRCSetup, RRCReconfiguration) of FIG. 3. The settings may include the following:

[0168] - useOnlyPrimary: Sets delay-critical data to be transmitted only from the Primary RLC (or Delay Critical Primary RLC) layer device. For example, this setting can only be used when the Primary RLC (or Delay Critical Primary RLC) layer device is a DSR-enabled RLC layer device.

[0169] - Dedicated Primary RLC layer device for delay-critical data (Delay-Critical Primary RLC layer device configured via delayCriticalPrimaryPath): When transmitting PDCP PDUs that are delay-critical data or include delay-critical data to lower layers, or when notifying the size of delay-critical PDCP data to the MAC layer, a dedicated Primary RLC layer device for delay-critical data (Delay-Critical Primary RLC layer device) can be configured. At this time, the Delay-Critical Primary RLC layer device can be indicated by indicating the Cell Group ID to which the RLC layer device belongs and the Logical Channel ID of the RLC layer device. In one example, the Delay-Critical Primary RLC layer device can be configured only for DSR-supporting RLC layer devices. In one example, when transmitting delay-critical data to lower layers, the Delay-Critical Primary RLC layer device can always have the PDCP redundancy transmission function enabled.

[0170] - Setting to enable PDCP duplication transmission function for delay-critical data (Delay-Critical pdcp-Duplication, Delay-Critical duplicationState): When transmitting a PDCP PDU including delay-critical data to a lower layer or notifying the size of delay-critical PDCP data to the MAC layer, a setting for whether to enable PDCP duplication transmission function can be separately set for delay-critical data for the associated RLC layer device. When the setting is set, whether to enable PDCP duplication transmission of the corresponding Radio Bearer / PDCP layer device and the associated RLC layer device in the embodiments of FIGS. 4 and 5 can be determined by the Delay-Critical pdcp-Duplication.

[0171] - Split Secondary RLC layer device for delay-critical data (configure Delay-Critical Split Secondary RLC layer device with delayCriticalSplitSecondaryPath): When operating as a Split Bearer, a dedicated Delay-Critical Split Secondary RLC layer device can be configured for delay-critical data. In one example, the Delay-Critical Split Secondary RLC layer device may belong to a different Cell Group from the Delay-Critical Primary RLC layer device. In one example, the Delay-Critical Split Secondary RLC layer device can only be configured for DSR-supporting RLC layer devices.

[0172] - Split Bearer threshold for delay-critical data (ul-DelayCriticalDataSplitThreshold): When transmitting a PDCP PDU that is delay-critical data or includes delay-critical data (Delay-Critical PDCP SDU) to a lower layer, a threshold can be set for whether to allow the use of a Split Secondary RLC layer device / Delay-Critical Split Secondary RLC layer device. The method of applying the ul-DelayCriticalDataSplitThreshold can be referred to the embodiment of FIG. 5.

[0173] According to one embodiment of the present disclosure, when a specific PDCP layer device of a terminal submits a PDCP PDU to a lower layer (RLC), the PDCP layer device may operate as follows.

[0174] If the number of RLC layer devices associated with the corresponding PDCP layer device is one, the corresponding PDCP PDU can be delivered to the associated RLC layer device.

[0175] When the number of RLC layer devices associated with a corresponding PDCP layer device is two or more (405, 410, 415, 420, 425), there may be several embodiments for how the PDCP layer device forwards PDCP PDUs to the multiple associated RLC layer devices. The following embodiments may be provided for the case where the PDCP redundant transmission function is activated for the Radio Bearer to which the corresponding PDCP layer device belongs.

[0176] Example 4-1:

[0177] - If the PDCP PDU is a PDCP Data PDU:

[0178] ● The PDCP PDU can be transmitted in duplicate to the RLC layer devices (405, 410, 415, 420, and 425) associated with the Radio Bearer / PDCP layer device, among which the PDCP duplicate transmission function is activated (405, 410, and 415). When transmitting the PDCP PDU in duplicate, the RLC layer devices (405, 410, 415, 420, and 425) associated with the Radio Bearer / PDCP layer device, among which the RLC layer devices (405, 410, 415, 420, and 425) associated with the Radio Bearer / PDCP layer device, among which the RLC layer devices (405, 410, 415, 420, and 425) are deactivated, can be excluded from the duplicate transmission.

[0179] - If the PDCP PDU is a PDCP Control PDU:

[0180] ● The PDCP PDU in question can be transmitted only to the Primary RLC layer device (405) without being transmitted in duplicate. This may be because the PDCP Control PDU does not have a PDCP Sequence Number in the PDCP header, and therefore duplication detection of PDCP Control PDUs received in duplicate at the other PDCP receiving device is not supported.

[0181] Example 4-2:

[0182] - If the PDCP PDU or the data (PDCP SDU) contained in the PDCP PDU is delay-critical data (belonging to the above delay-critical data-1 to 5, or belonging to the above delay-critical data-1 to 2):

[0183] ● The corresponding PDCP PDU can be transmitted only to the Primary RLC layer device (405) without being transmitted repeatedly. In one example, the above operation can be performed only when the Primary RLC layer device is a DSR-supporting RLC layer device, and otherwise, the operation of the above embodiment 4-1 can be performed for the corresponding PDCP PDU.

[0184] - Otherwise:

[0185] ● For the corresponding PDCP PDU, the operation of the above embodiment 4-1 can be performed.

[0186] Example 4-3:

[0187] - If useOnlyPrimary and / or delayCrticalPrimaryPath are set:

[0188] ● If the PDCP PDU or the data (PDCP SDU) contained in the PDCP PDU is delay-critical data (belonging to the above delay-critical data-1 to 5, or belonging to the above delay-critical data-1 to 2, or belonging to the above delay-critical data-1, 2, 4, 5):

[0189] * The corresponding PDCP PDU can be delivered only to the Primary RLC layer device (405) (if useOnlyPrimary is set) or the Delay Critical Primary RLC layer device (if delayCriticalPrimaryPath is set) without being transmitted in duplicate. For example, the PDCP Control PDU can be delivered only to the Primary RLC layer device or the Delay Critical Primary RLC layer device.

[0190] ●Else:

[0191] * For the corresponding PDCP PDU, the operation of the above embodiment 4-1 can be performed.

[0192] - Else:

[0193] ● For the corresponding PDCP PDU, the operation of the above embodiment 4-1 can be performed.

[0194] Referring to FIG. 4, when a transmitter of a PDCP layer device of a terminal has an association with two or more RLC layer devices, the PDCP layer device can operate as follows for the purpose of instructing a MAC layer device about DSR triggering and a delay-critical data buffer size.

[0195] Example 4-1-1:

[0196] - The size of the delay-critical data (Delay-Critical PDCP Data Volume) can be notified (indicated) to the MAC layer device associated with the Primary RLC layer device (in one example, based on the MAC layer device (based on the remainingTimeThreshold of the MAC)). For example, the size of the delay-critical data can be determined as the total size of the Delay-Critical Data-1 to 5 or the total size of the Delay-Critical Data-1 to 2. For example, the notification can be performed only when the Primary RLC layer device is a DSR-supporting RLC layer device.

[0197] - For each RLC layer device with PDCP redundancy transmission enabled, except for the Primary RLC layer device, the MAC layer device associated with the RLC layer device may be notified of the Delay-Critical PDCP Data Volume (in one example, based on the MAC layer device (based on the remainingTimeThreshold of the MAC)). For example, the Delay-Critical Data Volume may be determined as the total size of the Delay-Critical Data-1, 2, 4, 5 (excluding PDCP Control PDU because it is transmitted only in the Primary) or the total size of the Delay-Critical Data-1, 2. For example, the notification may be performed only when the RLC layer device is a DSR-supporting RLC layer device.

[0198] - For each RLC layer device with the PDCP redundancy transmission function deactivated among the associated RLC layer devices, the Delay-Critical PDCP Data Volume can be notified to the MAC layer device associated with the RLC layer device as 0. The notification can be performed only when the RLC layer device is a DSR-supporting RLC layer device.

[0199] Example 4-2-1:

[0200] - If the Primary RLC layer device is a DSR-enabled RLC layer device:

[0201] ● The size of the delay-critical data (Delay-Critical PDCP Data Volume) can be notified (indicated) to the MAC layer device associated with the Primary RLC layer device (in one example, based on the MAC layer device (based on the remainingTimeThreshold of the MAC)). For example, the size of the delay-critical data can be determined as the total size of the delay-critical data-1 to 5 or the total size of the delay-critical data-1 to 2.

[0202] ● For each MAC layer device associated with each RLC layer device with PDCP redundancy transmission enabled, except for the Primary RLC layer device, the size of delay-critical data (Delay-Critical PDCP Data Volume) may be notified as 0. The notification may be performed only when the RLC layer device is a DSR-supporting RLC layer device. At this time, for the purpose of BSR triggering and buffer size calculation, when notifying the PDCP data size (PDCP Data Volume) to the MAC layer device associated with each RLC layer device with PDCP redundancy transmission enabled, except for the Primary RLC layer device, the remaining PDCP data size excluding the delay-critical data (size of Delay-Critical Data-1 to 5 or size of Delay-Critical Data-1 to 2) may be notified (in one example, based on the MAC layer device associated with the Primary RLC).

[0203] - If the Primary RLC layer device is not a DSR-capable RLC layer device:

[0204] ● For each RLC layer device with PDCP redundancy transmission enabled, except for the Primary RLC layer device, the MAC layer device associated with the RLC layer device may be notified of the Delay-Critical PDCP Data Volume (in one example, based on the MAC layer device (based on the remainingTimeThreshold of the MAC)). For example, the Delay-Critical Data Volume may be determined as the total size of the Delay-Critical Data-1, 2, 4, 5 (excluding PDCP Control PDU because it is transmitted only in the Primary) or the total size of the Delay-Critical Data-1, 2. For example, the notification may be performed only when the RLC layer device is a DSR-supporting RLC layer device.

[0205] - For each RLC layer device among the associated RLC layer devices for which the PDCP redundancy transmission function is deactivated, the Delay-Critical PDCP Data Volume may be notified to the associated MAC layer device as 0. For example, the notification may be performed only when the RLC layer device is a DSR-supporting RLC layer device.

[0206] Example 4-3-1:

[0207] - If useOnlyPrimary and / or delayCrticalPrimaryPath are set:

[0208] ● The size of the delay-critical data (Delay-Critical PDCP Data Volume) can be indicated to the MAC layer device associated with the Primary RLC layer device (if useOnlyPrimary is set) or the Delay-Critical Primary RLC layer device (if delayCriticalPrimaryPath is set) (in one example, based on the corresponding MAC layer device (based on the remainingTimeThreshold of the corresponding MAC)). For example, the size of the delay-critical data can be determined as the total size of the Delay-Critical Data-1 to 5, the total size of the Delay-Critical Data-1 to 2, or the total size of Delay-Critical Data-1, 2, 4, 5 (if the Delay-Critical Primary Path and the Primary Path are different).

[0209] ● For each MAC layer device associated with each RLC layer device with PDCP redundancy transmission enabled, except for the Primary RLC layer device (if useOnlyPrimary is set) or the Delay-Critical Primary RLC layer device (delayCriticalPrimaryPath), the size of delay-critical data (Delay-Critical PDCP Data Volume) can be notified as 0. The notification can be performed only if the RLC layer device is a DSR-supporting RLC layer device. At this time, for the purpose of BSR triggering and buffer size calculation, when notifying the PDCP data size (PDCP Data Volume) to the MAC layer device associated with the RLC layer device, for each RLC layer device with PDCP redundancy transmission enabled, except for the Primary RLC layer device, the remaining PDCP data size excluding the delay-critical data (size of Delay-Critical Data-1 to 5 or size of Delay-Critical Data-1 to 2) can be notified (in one example, based on the MAC layer device associated with the Primary RLC).

[0210] ● For each RLC layer device among the associated RLC layer devices for which the PDCP redundancy transmission function is deactivated, the associated MAC layer device may be notified that the Delay-Critical PDCP Data Volume is 0. For example, the notification may be performed only when the RLC layer device is a DSR-supporting RLC layer device.

[0211] - Otherwise:

[0212] ● The operation of the above-described embodiment 4-1-1 can be performed.

[0213] FIG. 5 is a diagram illustrating an operation of transmitting delay-critical data to a lower layer (RLC) when a specific PDCP layer device of a terminal operates as a Split Bearer according to one embodiment of the present disclosure.

[0214] Referring to FIG. 5, when the number of RLC layer devices associated with a PDCP layer device (500) of a terminal is two or more, and when the PDCP duplicate transmission function of the corresponding PDCP layer device is disabled and a Split Secondary RLC layer device (520) / Delay Critical Split Secondary RLC layer device (520) is set, the terminal can operate as follows when transmitting a specific PDCP PDU to a lower layer.

[0215] Example 5-1:

[0216] - When the sum of the PDCP data size (PDCP Data Volume) of the corresponding PDCP layer device (500) and the RLC data size (RLC Data Volume) pending for initial transmission in the Primary (510) and Split Secondary (520) RLC layer devices is greater than or equal to ul-DataSplitThreshold:

[0217] ● The above PDCP PDU can be delivered to the Primary (510) RLC layer device or the Split Secondary (520) RLC layer device.

[0218] - Else:

[0219] ● The above PDCP PDU can be delivered to the Primary (510) RLC layer device. This may be for the purpose of reducing the reordering burden of the receiving PDCP layer device by using the Split Secondary RLC layer device only in a congestion situation and using only the Primary RLC layer device in non-congestion situations.

[0220] In one example, the aforementioned embodiment 5-1 can be performed consistently for all PDCP PDUs (regardless of whether they are delay critical data) delivered to lower layers.

[0221] Example 5-2:

[0222] - If the PDCP PDU or the PDCP SDU contained in the PDCP PDU is delay-critical data of the PDCP layer device (belonging to delay-critical data-1 to 5, or belonging to delay-critical data-1 to 2):

[0223] ● The above PDCP PDU can be delivered to a Primary RLC layer device / Delay Critical Primary RLC layer device or a Split Secondary RLC layer device / Delay Critical Split Secondary RLC layer device. This may be for the purpose of reducing delay by using both Cell Group resources in case of delay-critical data.

[0224] - Else: 0

[0225] ● The above PDCP PDU can be processed as in Example 5-1.

[0226] Example 5-3:

[0227] - If the PDCP PDU or the PDCP SDU contained in the PDCP PDU is delay-critical data of the PDCP layer device (belonging to delay-critical data-1 to 5, or belonging to delay-critical data-1 to 2):

[0228] ● If the sum of the PDCP data size (PDCP Data Volume) of the corresponding PDCP layer device (500) and the RLC data size (RLC Data Volume) pending for initial transmission in the Primary / Delay Critical Primary and Split Secondary / Delay Critical Split Secondary RLC layer devices is greater than or equal to ul-DelayCriticalDataSplitThreshold:

[0229] * The above PDCP PDU can be delivered to a Primary RLC layer device / Delay Critical Primary RLC layer device or a Split Secondary RLC layer device / Delay Critical Split Secondary RLC layer device.

[0230] ● Else:

[0231] * The corresponding PDCP PDU can only be delivered to Primary RLC / Delay Critical Primary RLC layer devices. In one example, the above-described operation can only be performed when the Primary RLC layer device is a DSR-supporting RLC layer device.

[0232] - Else:

[0233] ● The operation of Example 5-1 can be performed for the corresponding PDCP PDU.

[0234] Example 5-4:

[0235] - If the PDCP PDU or the PDCP SDU contained in the PDCP PDU is delay-critical data of the PDCP layer device (belonging to delay-critical data-1 to 5, or belonging to delay-critical data-1 to 2):

[0236] ● If the sum of the Delay Critical PDCP Data Volume of the corresponding PDCP layer device (500) and the Delay Critical RLC Data Volume pending for initial transmission in the Primary / Delay Critical Primary and Split Secondary / Delay Critical Split Secondary RLC layer devices is greater than or equal to ul-DelayCriticalDataSplitThreshold:

[0237] - The above PDCP PDU can be delivered to a Primary RLC layer device / Delay Critical Primary RLC layer device or a Split Secondary RLC layer device / Delay Critical Split Secondary RLC layer device.

[0238] ● If not:

[0239] * The corresponding PDCP PDU can only be delivered to Primary RLC / Delay Critical Primary RLC layer devices. In one example, the above operation can only be performed when the Primary RLC layer device is a DSR-supporting RLC layer device.

[0240] - Else:

[0241] ● The operation of Example 5-1 can be performed for the corresponding PDCP PDU.

[0242] Example 5-5:

[0243] - If the PDCP PDU or the PDCP SDU contained in the PDCP PDU is delay-critical data of the PDCP layer device (belonging to delay-critical data-1 to 5, or belonging to delay-critical data-1 to 2):

[0244] ● The PDCP PDU can only be delivered to Primary RLC / Delay Critical Primary RLC layer devices. This may be for the purpose of reducing reordering delay by using only Primary rather than Secondary Split and Primary together, even in congestion situations, for delay-critical data.

[0245] - Otherwise:

[0246] ● The operation of Example 5-1 can be performed for the corresponding PDCP PDU.

[0247] Example 5-6:

[0248] - If the PDCP PDU or the PDCP SDU contained in the PDCP PDU is delay-critical data of the PDCP layer device (belonging to delay-critical data-1 to 5, or belonging to delay-critical data-1 to 2):

[0249] ● If the base station has set the useOnlyPrimary or Delay Critical Primary RLC layer device:

[0250] * The PDCP PDU can only be delivered to Primary RLC (if useOnlyPrimary is set) / Delay Critical Primary RLC (if Delay Critical Primary RLC is set) layer devices. This may be intended to reduce reordering delays by using only Primary rather than using Secondary Split and Primary together, even in congestion situations, for delay-critical data.

[0251] ● If not:

[0252] * The operation of Example 5-1 can be performed for the corresponding PDCP PDU.

[0253] - Otherwise:

[0254] ● The operation of Example 5-1 can be performed for the corresponding PDCP PDU.

[0255] Referring to FIG. 5, when a transmitter of a PDCP layer device (500) of a terminal has an association with two or more RLC layer devices, the PDCP layer device may have the following embodiments when the PDCP redundant transmission function of the Radio Bearer of the corresponding PDCP layer device is disabled and a Split Secondary / Delay Critical Split Secondary RLC layer device (520) is set for the purpose of instructing the MAC layer device about DSR triggering and delay critical data buffer size.

[0256] Example 5-1-1:

[0257] - When the sum of the PDCP data size (PDCP Data Volume) of the corresponding PDCP layer device (500) and the RLC data size (RLC Data Volume) pending for initial transmission in the Primary (510) and Split Secondary (520) RLC layer devices is greater than or equal to ul-DataSplitThreshold:

[0258] ● (In one example, the delay-critical data size (Delay-Critical PDCP Data Volume) based on the MAC layer device (MAC1) (530) associated with the Primary RLC layer device (510) (based on the remainingTimeThreshold of the corresponding LCG of the corresponding MAC)) can be notified to the MAC layer device (MAC1) (530) associated with the Primary RLC layer device (510). In addition, (In one example, the delay-critical data size (Delay-Critical PDCP Data Volume) based on the MAC layer device (MAC2) (540) associated with the Split Secondary RLC layer device (520) (based on the remainingTimeThreshold of the corresponding LCG of the corresponding MAC)) can be notified to the MAC layer device (MAC2) (540) associated with the Split Secondary RLC layer device (520). For example, the notification to the MAC layer device associated with the Primary / Split Secondary RLC can be performed only when the corresponding RLC layer device is a DSR-supporting RLC layer device. This is because the LTE MAC layer device may not support DSR.

[0259] ● For the Delay-Critical PDCP Data Volume, other associated RLC layer devices except the Primary RLC layer device (510) and the Split Secondary RLC layer device (520) may be notified as 0 to the MAC layer device associated with the RLC layer device. For example, the notification may be performed only when the RLC layer device is a DSR-supporting RLC layer device.

[0260] - Else:

[0261] ● (In one example, the delay-critical PDCP Data Volume can be notified only to the MAC layer device (530) associated with the Primary RLC layer device (510) (based on the remainingTimeThreshold of the corresponding LCG of the corresponding MAC) based on the MAC layer device (MAC1) (530) associated with the Primary RLC layer device (510). For example, the notification can be performed only when the Primary RLC layer device is a DSR-supporting RLC layer device. This is because the LTE MAC layer device may not support DSR.

[0262] ● For delay-critical data sizes, other associated RLC layer devices, excluding the Primary RLC layer device, may be notified as 0 to each MAC layer device associated with the RLC layer device. For example, the notification may be performed only when the RLC layer device is a DSR-supporting RLC layer device. This is because LTE MAC layer devices may not support DSR.

[0263] Example 5-2-1:

[0264] - A PDCP layer device can notify the delay critical data size to a MAC layer device associated with a Primary / Delay Critical Primary RLC layer device. For example, the delay critical data size can be determined as the total size of Delay Critical Data-1 to 5 or the total size of Delay Critical Data-1 to 2. A PDCP layer device can notify the delay critical data size to a MAC layer device associated with a Split Secondary / Delay Critical Split Secondary RLC layer device. For example, the delay critical data size can be determined as the total size of Delay Critical Data-1 to 5 or the total size of Delay Critical Data-1 to 2. For example, notification of the delay critical data size to a MAC layer device associated with a Primary or Secondary RLC layer device can be performed only when the RLC layer device is a DSR-supporting RLC layer device.

[0265] - A PDCP layer device may, for each associated RLC layer device other than a Primary / Delay Critical Primary RLC layer device and a Split Secondary / Delay Critical Split Secondary RLC layer device, notify the MAC layer device associated with the RLC layer device of the delay critical data size as 0, if the RLC layer device is a DSR-supporting RLC layer device.

[0266] Example 5-3-1:

[0267] - When the sum of the PDCP data size (PDCP Data Volume) of the corresponding PDCP layer device (500) and the RLC data size (RLC Data Volume) pending for initial transmission in the Primary / Delay Critical Primary and Split Secondary / Delay Critical Split Secondary RLC layer devices is greater than or equal to ul-DelayCriticalDataSplitThreshold:

[0268] ● A PDCP layer device can notify the delay critical data size to a MAC layer device associated with a Primary / Delay Critical Primary RLC layer device. For example, the delay critical data size may be determined as the total size of Delay Critical Data-1 to 5 or the total size of Delay Critical Data-1 to 2. A PDCP layer device can notify the delay critical data size to a MAC layer device associated with a Split Secondary / Delay Critical Split Secondary RLC layer device. For example, the delay critical data size may be determined as the total size of Delay Critical Data-1 to 5 or the total size of Delay Critical Data-1 to 2. For example, notification of the delay critical data size to a MAC layer device associated with a Primary or Secondary RLC layer device can be performed only when the RLC layer device is a DSR-supporting RLC layer device.

[0269] ● A PDCP layer device may, for each associated RLC layer device other than Primary / Delay Critical Primary RLC layer devices and Split Secondary / Delay Critical Split Secondary RLC layer devices, notify the MAC layer device associated with the RLC layer device of the delay critical data size as 0 if the RLC layer device is a DSR-supporting RLC layer device.

[0270] - Else

[0271] ● A PDCP layer device can notify the MAC layer device associated with the Primary / Delay Critical Primary RLC layer device of the delay critical data size. For example, the delay critical data size can be determined as the total size of Delay Critical Data-1 to 5 or the total size of Delay Critical Data-1 to 2. For example, notification of the delay critical data size to the MAC layer device associated with the Primary RLC layer device can be performed only when the RLC layer device is a DSR-supporting RLC layer device.

[0272] ● A PDCP layer device may, for each associated RLC layer device other than the Primary / Delay Critical Primary RLC layer device, notify the MAC layer device associated with the RLC layer device of the delay critical data size as 0 if the RLC layer device is a DSR-supporting RLC layer device.

[0273] Example 5-4-1:

[0274] - When the sum of the Delay Critical PDCP Data Volume of the corresponding PDCP layer device (500) and the Delay Critical RLC Data Volume pending for initial transmission in the Primary / Delay Critical Primary and Split Secondary / Delay Critical Split Secondary RLC layer devices is greater than or equal to ul-DelayCriticalDataSplitThreshold:

[0275] ● A PDCP layer device can notify the delay critical data size to a MAC layer device associated with a Primary / Delay Critical Primary RLC layer device. For example, the delay critical data size may be determined as the total size of Delay Critical Data-1 to 5 or the total size of Delay Critical Data-1 to 2. A PDCP layer device can notify the delay critical data size to a MAC layer device associated with a Split Secondary / Delay Critical Split Secondary RLC layer device. For example, the delay critical data size may be determined as the total size of Delay Critical Data-1 to 5 or the total size of Delay Critical Data-1 to 2. For example, notification of the delay critical data size to a MAC layer device associated with a Primary or Secondary RLC layer device can be performed only when the RLC layer device is a DSR-supporting RLC layer device.

[0276] ● A PDCP layer device may, for each associated RLC layer device other than Primary / Delay Critical Primary RLC layer devices and Split Secondary / Delay Critical Split Secondary RLC layer devices, notify the MAC layer device associated with the RLC layer device of the delay critical data size as 0 if the RLC layer device is a DSR-supporting RLC layer device.

[0277] - Else

[0278] ● A PDCP layer device can notify the MAC layer device associated with the Primary / Delay Critical Primary RLC layer device of the delay critical data size. For example, the delay critical data size can be determined as the total size of Delay Critical Data-1 to 5 or the total size of Delay Critical Data-1 to 2. For example, notification of the delay critical data size to the MAC layer device associated with the Primary RLC layer device can be performed only when the RLC layer device is a DSR-supporting RLC layer device.

[0279] ● A PDCP layer device may, for each associated RLC layer device other than the Primary / Delay Critical Primary RLC layer device, notify the MAC layer device associated with the RLC layer device of the delay critical data size as 0 if the RLC layer device is a DSR-supporting RLC layer device.

[0280] Example 5-5-1:

[0281] - A PDCP layer device may notify the MAC layer device associated with the Primary / Delay Critical Primary RLC layer device of the delay critical data size. For example, the delay critical data size may be determined as the total size of Delay Critical Data-1 to 5 or the total size of Delay Critical Data-1 to 2. For example, notification of the delay critical data size to the MAC layer device associated with the Primary RLC layer device may be performed only when the RLC layer device is a DSR-supporting RLC layer device.

[0282] - A PDCP layer device may, for each associated RLC layer device other than the Primary / Delay Critical Primary RLC layer device, notify the MAC layer device associated with the RLC layer device of the delay critical data size as 0, if the RLC layer device is a DSR-supporting RLC layer device.

[0283] Example 5-6-1:

[0284] - If the base station has set the useOnlyPrimary or Delay Critical Primary RLC layer device:

[0285] ● A PDCP layer device can notify the MAC layer device associated with the Primary / Delay Critical Primary RLC layer device of the delay critical data size. For example, the delay critical data size can be determined as the total size of Delay Critical Data-1 to 5 or the total size of Delay Critical Data-1 to 2. For example, notification of the delay critical data size to the MAC layer device associated with the Primary RLC layer device can be performed only when the RLC layer device is a DSR-supporting RLC layer device.

[0286] ● A PDCP layer device may, for each associated RLC layer device other than the Primary / Delay Critical Primary RLC layer device, notify the MAC layer device associated with the RLC layer device of the delay critical data size as 0 if the RLC layer device is a DSR-supporting RLC layer device.

[0287] - If not:

[0288] ● Example 5-1-1 can be performed.

[0289] FIG. 6 is a diagram illustrating a method by which a PDCP layer device (600) operating as a DAPS Bearer of a terminal processes delay-critical data, according to an embodiment of the present disclosure.

[0290] Referring to FIG. 6, when a transmitting PDCP layer device (600) is associated with a DAPS Bearer, the following embodiments may exist.

[0291] Example 6-1:

[0292] - If Uplink Data Switching has not yet been requested:

[0293] ● The delay-critical PDCP data size can be notified to the MAC layer device (630) associated with the source cell through the RLC layer device (610) associated with the source cell.

[0294] - Otherwise:

[0295] ● The delay-critical PDCP data size, excluding the PDCP Control PDU for Interspersed ROHC Feedback associated with the source cell, can be notified to the MAC layer device (640) associated with the target cell through the RLC layer device (620) associated with the target cell. For example, the notification can be performed only when the MAC layer device associated with the target cell supports DSR or DSR is set.

[0296] * The MAC layer device associated with the source cell may be notified of the delay-critical PDCP data size as 0. This is because if only the PDCP Control PDU for Interspersed ROHC Feedback exists, the PDCP Control PDU may not be considered as delay-critical data.

[0297] Example 6-2:

[0298] - If Uplink Data Switching has not yet been requested:

[0299] ● The delay-critical PDCP data size can be notified to the MAC layer device (630) associated with the source cell through the RLC layer device (610) associated with the source cell.

[0300] - Otherwise:

[0301] ● The delay-critical PDCP data size, excluding the PDCP Control PDU for Interspersed ROHC Feedback associated with the source cell, can be notified to the MAC layer device (640) associated with the target cell through the RLC layer device (620) associated with the target cell. For example, the notification can be performed only when the MAC layer device associated with the target cell supports DSR.

[0302] ● The delay-critical PDCP data size can be notified to the MAC layer device (630) associated with the source cell through the RLC layer device (610) associated with the source cell as the size of the PDCP Control PDU for Interspersed ROHC Feedback associated with the source cell.

[0303] FIG. 7 illustrates the structure of a base station according to one embodiment of the present disclosure.

[0304] Referring to FIG. 7, the base station may include a transceiver (710), a control unit (720), and a storage unit (730). The transceiver (710), the control unit (720), and the storage unit (730) may operate according to the communication method of the base station described above. The network device may also correspond to the structure of the base station. However, the components of the base station are not limited to the examples described above. For example, the base station may include more or fewer components than the components described above. For example, the base station may include a transceiver (710) and a control unit (720). In addition, the transceiver (710), the control unit (720), and the storage unit (730) may be implemented in the form of a single chip.

[0305] The transceiver (710) is a general term for the receiving unit and the transmitting unit of the base station, and can transmit and receive signals with terminals, other base stations, or other network devices. At this time, the transmitted and received signals may include control information and data. The transceiver (710) may, for example, transmit system information to the terminal, and transmit a synchronization signal or a reference signal. To this end, the transceiver (710) may be configured with an RF transmitter that up-converts and amplifies the frequency of a transmitted signal, and an RF receiver that low-noise amplifies and frequency-down-converts a received signal. However, this is only one embodiment of the transceiver (710), and the components of the transceiver (710) are not limited to the RF transmitter and RF receiver. The transceiver (710) may include wired and wireless transceivers, and may include various configurations for transmitting and receiving signals. In addition, the transceiver (710) can receive a signal through a communication channel (e.g., a wireless channel) and output it to the control unit (720), and transmit the signal output from the control unit (720) through the communication channel. In addition, the transceiver (710) can receive a communication signal and output it to the processor, and transmit the signal output from the processor to a terminal, another base station, or another entity through a wired or wireless network.

[0306] The storage unit (730) can store programs and data required for the operation of the base station. In addition, the storage unit (730) can store control information or data included in signals acquired from the base station. The storage unit (730) can be configured as a storage medium or a combination of storage media, such as a ROM, a RAM, a hard disk, a CD-ROM, and a DVD. In addition, the storage unit (730) can store at least one of information transmitted and received through the transceiver unit (710) and information generated through the control unit (720).

[0307] In the present disclosure, the control unit (720) may be defined as a circuit or application-specific integrated circuit, or at least one processor. The processor may include a communication processor (CP) that performs control for communication and an application processor (AP) that controls upper layers such as application programs. The control unit (720) may control the overall operation of the base station according to the embodiment proposed in the present disclosure. For example, the control unit (720) may control the signal flow between each block to perform operations according to the flowchart described above.

[0308] Figure 8 illustrates the structure of a terminal according to one embodiment of the present disclosure.

[0309] Referring to FIG. 8, the terminal may include a transceiver (810), a control unit (820), and a storage unit (830). The transceiver (810), the control unit (820), and the storage unit (830) may operate according to the communication method of the terminal described above. However, the components of the terminal are not limited to the examples described above. For example, the terminal may include more or fewer components than the components described above. For example, the terminal may include a transceiver (810) and a control unit (820). In addition, the transceiver (810), the control unit (820), and the storage unit (830) may be implemented in the form of a single chip.

[0310] The transceiver (810) is a general term for the receiving unit and the transmitting unit of the terminal, and can transmit and receive signals with a base station, another terminal, or a network entity. The signals transmitted and received with the base station may include control information and data. The transceiver (810) may, for example, receive system information from the base station and receive a synchronization signal or a reference signal. To this end, the transceiver (810) may be configured with an RF transmitter that up-converts and amplifies the frequency of a transmitted signal, and an RF receiver that low-noise amplifies and frequency-downconverts the received signal. However, this is only one embodiment of the transceiver (810), and the components of the transceiver (810) are not limited to the RF transmitter and RF receiver. In addition, the transceiver (810) may include a wired or wireless transceiver, and may include various configurations for transmitting and receiving signals. In addition, the transceiver (810) can receive a signal through a wireless channel and output it to the control unit (820), and transmit the signal output from the control unit (820) through the wireless channel. In addition, the transceiver (810) can receive a communication signal and output it to the processor, and transmit the signal output from the processor to a network entity through a wired or wireless network.

[0311] The storage unit (830) can store programs and data necessary for the operation of the terminal. In addition, the memory (830) can store control information or data included in signals acquired from the terminal. The storage unit (830) can be configured as a storage medium such as a ROM, RAM, hard disk, CD-ROM, and DVD, or a combination of storage media.

[0312] In the present disclosure, the control unit (820) may be defined as a circuit or application-specific integrated circuit, or at least one processor. The processor may include a communication processor (CP) that performs control for communication and an application processor (AP) that controls upper layers such as application programs. The control unit (820) may control the overall operation of the terminal according to the embodiment proposed in the present disclosure. For example, the control unit (820) may control the signal flow between each block to perform operations according to the flowchart described above.

[0313] The 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.

[0314] When implemented in software, a computer-readable storage medium storing one or more programs (software modules) may be provided. The one or more programs stored in the computer-readable storage medium are configured for execution by one or more processors within an electronic device. The one or more programs include instructions that cause the electronic device to execute methods according to the embodiments described in the claims or specification of the present invention.

[0315] These programs (software modules, software) may be stored in random access memory, non-volatile memory including flash memory, read only memory (ROM), electrically erasable programmable read only memory (EEPROM), magnetic disc storage devices, compact disc ROMs (CD-ROMs), digital versatile discs (DVDs) or other forms of optical storage devices, magnetic cassettes, or may be stored in memories formed by a combination of some or all of these. In addition, each configuration memory may include multiple copies.

[0316] Additionally, the program may be stored in an attachable storage device that is accessible via a communication network such as the Internet, an intranet, a local area network (LAN), a wide local area network (WLAN), a storage area network (SAN), or a combination thereof. Such a storage device may be connected to a device implementing an embodiment of the present invention via an external port. Additionally, a separate storage device on the communication network may be connected to a device implementing an embodiment of the present invention.

[0317] In the specific embodiments of the present disclosure described above, components included in the disclosure are expressed in the singular or plural form, depending on the specific embodiment presented. However, the singular or plural expressions are selected to suit the presented situation for convenience of explanation, and the present disclosure is not limited to singular or plural components. Components expressed in the plural form may be composed of singular elements, or components expressed in the singular form may be composed of plural elements.

[0318] Meanwhile, although specific embodiments have been described in the detailed description of the present disclosure, it is obvious that various modifications are possible without departing from the scope of the present disclosure. Therefore, the scope of the present disclosure should not be limited to the described embodiments, but should be determined not only by the scope of the following claims but also by equivalents of the scope of the claims. In other words, it will be apparent to those skilled in the art to which the present disclosure pertains that other modifications based on the technical idea of ​​the present disclosure are possible. In addition, each of the above embodiments can be combined and operated with each other as needed. For example, parts of the methods proposed in the present disclosure can be combined with each other to operate a base station and a terminal. In addition, although the above embodiments have been presented based on a 5G, NR system, other modifications based on the technical idea of ​​the above embodiments can be implemented with other systems such as LTE, LTE-A, and LTE-A-Pro systems.

Claims

1. A method performed by a terminal (user equipment) in a wireless communication system, A step of identifying a first RLC entity, which is a primary RLC entity, and a second RLC entity, which is a split secondary RLC entity, among a plurality of RLC (radio link control) entities related to a PDCP (packet data convergence protocol) entity; A step of identifying whether the sum of the PDCP data volume of the PDCP entity, the first RLC data size of the first RLC entity, and the second RLC data size of the second RLC entity is greater than or equal to a first threshold; If the sum of the PDCP data size, the first RLC data size, and the second RLC data size is greater than or equal to the first threshold: The first MAC (medium access co) associated with the first RLC entity a step of indicating the size of delay critical PDCP data to a second MAC entity associated with the second RLC entity and the first RLC entity; and A method comprising the step of indicating to the first MAC entity or the second MAC entity associated with a third RLC entity, excluding the first RLC entity and the second RLC entity among the plurality of RLC entities, the size of the delay-critical PDCP data as 0.

2. In claim 1, the method comprises: If the sum of the PDCP data size, the first RLC data size, and the second RLC data size is less than the first threshold value: A step of indicating to the first MAC entity associated with the first RLC entity the size of the delay critical PDCP data; and A method comprising the step of indicating to the first MAC entity or the second MAC entity associated with a fourth RLC entity, excluding the first RLC entity, among the plurality of RLC entities, the size of the delay-critical PDCP data as 0.

3. In claim 1, A method wherein the above delay critical PDCP data is indicated to trigger a delay status report (DSR).

4. In claim 1, A method wherein the first threshold is indicated by PDCP configuration information received via RRC (radio resource control) signaling.

5. In claim 1, The first RLC entity or the second RLC entity is indicated by PDCP configuration information received via RRC signaling, A method wherein PDCP duplication for the above PDCP entity is disabled.

6. In claim 1, the method comprises: A step of identifying whether the sum of the PDCP data size of the PDCP entity, the first RLC data size of the first RLC entity, and the second RLC data size of the second RLC entity is greater than or equal to a second threshold for the split bearer; If the sum of the PDCP data size, the first RLC data size, and the second RLC data size is greater than or equal to the second threshold: Indicating the size of the delay-critical PDCP data to the first MAC entity associated with the first RLC entity and the second MAC entity associated with the second RLC entity; and A method further comprising the step of indicating to the first MAC entity or the second MAC entity associated with the third RLC entity, excluding the first RLC entity and the second RLC entity among the plurality of RLC entities, the size of the delay-critical PDCP data to be 0.

7. In claim 6, A method wherein the second threshold is used to identify whether to forward the delay critical PDCP data to the second RLC entity.

8. In claim 1, The above first RLC entity and the above second RLC entity support DSR, Delay critical PDCP data for the first RLC entity is indicated based on a remaining time threshold for the first logical channel group (LCG) corresponding to the first MAC entity, A method wherein delay critical PDCP data for the second RLC entity is indicated based on a remaining time threshold for the second LCG corresponding to the second MAC entity.

9. In a wireless communication system, in the terminal (user equipment), transceiver; and A controller coupled with the above transmitter and receiver is included, The above controller, Identify a first RLC entity, which is a primary RLC entity, and a second RLC entity, which is a split secondary RLC entity, among multiple RLC (radio link control) entities related to a PDCP (packet data convergence protocol) entity, Identify whether the sum of the PDCP data volume of the PDCP entity, the first RLC data size of the first RLC entity, and the second RLC data size of the second RLC entity is greater than or equal to a first threshold, If the sum of the PDCP data size, the first RLC data size, and the second RLC data size is greater than or equal to the first threshold: Indicate the size of delay critical PDCP data to the first MAC (medium access control) entity associated with the first RLC entity and the second MAC entity associated with the second RLC entity, A terminal configured to indicate to the first MAC entity or the second MAC entity associated with a third RLC entity, excluding the first RLC entity and the second RLC entity among the plurality of RLC entities, the size of the delay-critical PDCP data to be 0.

10. In claim 9, the controller, If the sum of the PDCP data size, the first RLC data size, and the second RLC data size is less than the first threshold value: A step of indicating to the first MAC entity associated with the first RLC entity the size of the delay critical PDCP data; and A terminal configured to indicate to the first MAC entity or the second MAC entity associated with a fourth RLC entity, excluding the first RLC entity, among the plurality of RLC entities, the size of the delay-critical PDCP data as 0.

11. In claim 9, The above delay critical PDCP data is indicated to trigger a delay status report (DSR) of the terminal.

12. In claim 9, The above first threshold value is indicated by the PDCP configuration information received via RRC (radio resource control) signaling.

13. In claim 9, The first RLC entity or the second RLC entity is indicated by PDCP configuration information received via RRC signaling, A terminal wherein PDCP duplication for the above PDCP entity is disabled.

14. In claim 9, the controller, Identifying whether the sum of the PDCP data size of the above PDCP entity, the first RLC data size of the first RLC entity, and the second RLC data size of the second RLC entity is greater than or equal to a second threshold for the split bearer, If the sum of the PDCP data size, the first RLC data size, and the second RLC data size is greater than or equal to the second threshold: Indicate the size of the delay-critical PDCP data to the first MAC entity associated with the first RLC entity and the second MAC entity associated with the second RLC entity, A terminal further configured to indicate to the first MAC entity or the second MAC entity associated with the third RLC entity, excluding the first RLC entity and the second RLC entity among the plurality of RLC entities, the size of the delay-critical PDCP data to be 0.

15. In claim 14, A second threshold for split bearer is used by the terminal to identify whether to forward the delay critical PDCP data to the second RLC entity.

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