Method and device for low latency RLC polling for low latency data in wireless communication system

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting higher data transmission rates. The present disclosure proposes a method and device for a terminal and base station to perform low-latency RLC polling for low-latency data in a wireless communication system.

Description

Low-latency RLC polling method and device for low-latency data in a wireless communication system

[0001] The present invention relates to the operation of a terminal and a base station in a wireless communication system. More specifically, the present invention relates to a method and apparatus for performing low-latency RLC (Radio Link Control) polling for low-latency data in a wireless communication system.

[0002] 5G (5th generation) 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 (6th generation) mobile communication technology, which is called the system after 5G communication (Beyond 5G), implementation in the terahertz band (for example, the 3 terahertz (3THz) 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] When such 5G mobile communication systems are commercialized, an explosive increase in connected devices will be connected to the communication network, which will require enhanced functions and performance of 5G mobile communication systems and integrated operation of 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 embodiment disclosed in the present invention is intended to provide a method and device capable of effectively providing a service in a mobile communication system.

[0009] The present disclosure aims to perform RLC Polling.

[0010] The technical problems to be achieved in the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present invention belongs from the description below.

[0011] Based on the discussion described above, the present disclosure provides a method for processing a control signal in a mobile communication system, which may include: receiving a first control signal transmitted from a base station; processing the received first control signal; and transmitting a second control signal generated based on the processing to the base station.

[0012] The disclosed embodiments provide a device and method for effectively providing services in a mobile communication system. Specifically, the present disclosure provides a method and device for performing RLC polling.

[0013] The effects that can be obtained from the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by a person having ordinary skill in the art to which the present disclosure pertains from the description below.

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

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

[0016] FIG. 3 is a diagram illustrating a procedure in which a base station sets settings for an RLC layer device (RLC Entity) of a terminal using an RRC (Radio Resource Control) message when a terminal establishes a connection with a network according to an embodiment of the present invention.

[0017] FIG. 4 is a diagram illustrating a procedure for performing RLC Polling of an RLC layer device of a terminal according to an embodiment of the present disclosure.

[0018] FIG. 5 is a diagram illustrating an RLC Polling procedure in an AM RLC layer device according to an embodiment of the present disclosure.

[0019] FIG. 6A is a diagram illustrating an AM RLC PDU format according to one embodiment of the present disclosure.

[0020] FIG. 6b is a diagram illustrating an AM RLC PDU format according to an embodiment of the present disclosure.

[0021] FIG. 6c is a diagram illustrating an AM RLC PDU format according to one embodiment of the present disclosure.

[0022] FIG. 6d is a diagram illustrating an AM RLC PDU format according to one embodiment of the present disclosure.

[0023] FIG. 7 is a block diagram illustrating the internal structure of a terminal according to an embodiment of the present disclosure.

[0024] FIG. 8 is a block diagram showing the configuration of a base station according to an embodiment of the present disclosure.

[0025] 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.

[0026] In the following description of the present invention, detailed descriptions of known functions or configurations will be omitted if they are deemed to unnecessarily obscure the gist of the present invention. Hereinafter, embodiments of the present invention will be described with reference to the attached drawings.

[0027] The operating principles of the present invention are described in detail with reference to the attached diagram. The terms described below are defined based on their functions within the present invention. These terms may vary depending on the intent or custom of the user or operator, and therefore their definitions should be determined based on the overall content of this specification.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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).

[0032] 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.

[0033] 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.

[0034] 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 with 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.

[0035] 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.

[0036] 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.

[0037] Certain terms used in the following description are provided to aid in understanding the present disclosure, and the use of such specific terms may be changed to other forms without departing from the technical spirit of the present disclosure.

[0038] FIG. 1 is a diagram illustrating the structure of an NR system according to one embodiment of the present disclosure.

[0039] Referring to FIG. 1, the wireless communication system may be configured with at least one of multiple base stations (e.g., gNB (100), ng-eNB (110), ng-eNB (120), or gNB (130)), an Access and Mobility Management Function (AMF) (140), and a User Plane Function (UPF) (150). The wireless communication system is not limited to the configuration illustrated in FIG. 1, and may include more or fewer components.

[0040] According to one embodiment of the present disclosure, a user equipment (hereinafter referred to as UE, terminal or terminal) (160) can access an external network through at least one of the base stations (100, 110, 120, 130) or UPF (150).

[0041] In FIG. 1, base stations (100, 110, 120, or 130) may 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) may collect at least one state information, such as a buffer state, an available transmission power state, or a channel state, of terminals to perform scheduling in order to service user traffic. Base stations may support connections between terminals and a core network (CN). CN of NR (New Radiation) may mean 5GC (5th Generation Core Network).

[0042] The gNB (100, 130) can control multiple cells. The gNB can apply an adaptive modulation and coding (AMC) method that determines a modulation scheme and channel coding rate according to the channel conditions of the terminal.

[0043] The core network can be a device responsible for various control functions, including mobility management for terminals. The core network can be connected to multiple base stations. Furthermore, 5GC can be integrated with existing LTE systems.

[0044] 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 can be configured separately. gNB (100) and gNB (130) can use UP and CP technologies defined in NR technology. ng-eNB (110) and ng-eNB (120) can use UP and CP technologies defined in LTE (Long Term Evolution) technology.

[0045] AMF (140) can perform mobility management functions for a terminal. AMF is a device responsible for control functions and can be connected to multiple base stations.

[0046] UPF (150) may refer to a gateway device that provides data transmission. The NR wireless communication system may include a Session Management Function (SMF). The SMF may manage packet data network connections, such as PDU (protocol data unit) sessions provided to terminals.

[0047] FIG. 2 is a diagram illustrating a wireless protocol structure in an NR system according to an embodiment of the present disclosure.

[0048] Referring to FIG. 2, the wireless protocol of the NR system may be composed of at least one of SDAP (Service Data Adaptation Protocol) (200), PDCP (Packet Data Convergence Protocol) (210), RLC (Radio Link Control) (220), MA C (Medium Access Control) (230), or PHY (Physical) (240) in the terminal.

[0049] The wireless protocol of the NR system may be composed of at least one of SDAP (Service Data Adaptation Protocol) (290), PDCP (Packet Data Convergence Protocol) (280), RLC (Radio Link Control) (270), MA C (Medium Access Control) (260), or PHY (Physical) (250) at the base station.

[0050] SDAP (Service Data Adaptation Protocol) (200 or 290) can carry user data. SDAP can perform at least one of the following operations: mapping QoS (Quality of Service) flows to specific DRBs (Data Radio Bearers) for uplink and downlink, marking QoS flow IDs (Identifiers) for uplink and downlink, or mapping reflective QoS flows to data bearers for uplink SDAP PDUs. SDAP settings corresponding to each DRB can be provided from a higher RRC layer. However, this is only one embodiment, and the operation or function of SDAP is not limited to the above example.

[0051] PDCP (Packet Data Convergence Protocol) (210 or 280) can perform compression and / or decompression of IP (Internet Protocol) headers, etc. In addition, PDCP (210 or 280) can provide at least one of the following functions: in-order and / or out-of-order delivery function, reordering, duplicate detection, retransmission function, encryption or decryption function. However, this is only one embodiment, and the operation or function of PDCP is not limited to the above example.

[0052] Radio Link Control (RLC) (220 or 270) can reconfigure PDCP Protocol Data Unit (PDU) to an appropriate size. RLC (220 or 270) can provide at least one of in-order and / or out-of-order delivery function, ARQ function, joining, segmentation, reassembly function, re-segmentation function, reordering function, duplicate detection function, or error detection function. However, this is only one embodiment, and the operation or function of RLC is not limited to the above example.

[0053] The MAC (230 or 260) can be connected to multiple RLC layer devices configured in a single terminal. The MAC can perform at least one of the following operations: multiplexing RLC PDUs into MAC PDUs or demultiplexing RLC PDUs from MAC PDUs. The MAC can provide at least one of a mapping function, a scheduling information reporting function, a 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, or a padding function. However, this is only one embodiment, and the operation or function of the MAC is not limited to the above example.

[0054] The physical (PHY) layer (240 or 250) can generate OFDM symbols by channel coding and modulating upper layer data, and transmit the OFDM symbols through a wireless channel. The PHY layer can demodulate OFDM symbols received through a wireless channel, perform channel decoding, and transmit them to a higher layer. The PHY layer can use HARQ (Hybrid ARQ (Automatic Repeat and Request)) for additional error correction. The receiver can transmit 1 bit to indicate whether or not a packet transmitted by the transmitter has been received. The 1 bit information can be HARQ ACK (Acknowledgement) or NACK (Negative Acknowledgement) information.

[0055] Downlink HARQ ACK or NACK information for uplink data transmission can be transmitted via the Physical Hybrid-ARQ Indicator Channel (PHICH) physical channel in the case of LTE. In the case of NR, whether retransmission is necessary or whether new transmission is performed can be determined through the terminal's scheduling information on the Physical Downlink Control Channel (PDCCH), which is the channel through which downlink or uplink resource allocation, etc. are transmitted. This is because NR can apply asynchronous HARQ.

[0056] Uplink HARQ ACK or NACK information for downlink data transmission can be transmitted via the Physical Uplink Control Channel (PUCCH) or Physical Uplink Shared Channel (PUSCH) physical channel. PUCCH can be transmitted in the uplink of the PCell. If the UE supports it, PUCCH can be transmitted in the SCell. For example, if the UE supports it, PUCCH can be transmitted in the uplink of the SCell from the UE to the base station. Here, SCell can refer to the PUCCH (Physical Uplink Control Channel) SCell.

[0057] Above the PDCP layer of the terminal and base station, an RRC (Radio Resource Control) layer may exist. The RRC layer can transmit and receive access and / or measurement-related configuration control messages for radio resource control.

[0058] The physical layer may be composed of at least one frequency or at least one carrier. A technology that simultaneously sets and uses multiple frequencies may refer to carrier aggregation (CA). A single carrier may be used for communication between a terminal (or UE or terminal) and a base station (eNB or gNB). When CA technology is used, a primary carrier and at least one secondary carrier may be used for communication between the terminal and the base station. In this case, the data transmission amount may increase according to the increased number of secondary carriers. A cell within a base station that uses a primary carrier in LTE or NR may refer to a primary cell or PCell (Primary Cell). A cell within a base station that uses a subcarrier in LTE or NR may refer to a secondary cell or SCell (Secondary Cell).

[0059] FIG. 3 is a diagram illustrating a procedure in which a base station sets settings for an RLC layer device (RLC Entity) of a terminal using an RRC (Radio Resource Control) message when a terminal establishes a connection with a network according to an embodiment of the present invention.

[0060] Referring to FIG. 3, in the present disclosure, a terminal can establish a connection with a network by switching from RRC idle mode (RRC_IDLE) to RRC connected mode (RRC_CONNECTED). The terminal can establish uplink or downlink transmission synchronization with a base station through a random access process. The terminal can transmit an RRCSetupRequest message to the base station in step 300 (300). The RRCSetupRequest message can include an identifier of the terminal or a reason for establishing a connection (e.g., EstablishmentCause). The base station can transmit an RRCSetup message to the terminal in step 305 so that the terminal can establish an RRC connection (305).

[0061] For example, the RRCSetup message may include configuration information (e.g., RadioBearerConfig) for each Radio Bearer (e.g., at least one of Data Radio Bearers (DRB) or Signaling Radio Bearer (SRB)). The Radio Bearer configuration information may include an ID of each Radio Bearer, configuration information for the PDCP layer device of the Radio Bearer (e.g., PDCP-Config), an indicator indicating whether it is a Dual Active Protocol Stack (DAPS) Bearer, etc.

[0062] For example, the RRCSetup message may include, for each Cell Group (e.g., at least one of the Master Cell Group (MCG) or the Secondary Cell Group (SCG)), RLC Bearer configuration information (e.g., RLC-BearerConfig) belonging to that Cell Group. The RLC Bearer configuration information may include at least one of the following information:

[0063] - logicalChannelIdentity: Can indicate the LCID corresponding to the RLC Bearer and / or RLC layer device (RLC Entity).

[0064] - servedRadioBearer: May indicate a Radio Bearer ID associated with an RLC Bearer and / or an RLC layer device (RLC Entity). The Radio Bearer ID may indicate at least one of a specific DRB or SRB.

[0065] - rlc-Config: You can indicate the RLC layer parameter setting information of the RLC layer device (RLC Entity) of the RLC Bearer.

[0066] For example, rlc-Config may contain at least one of the following configuration information:

[0067] - When the RLC layer device is set to AM (Acknowledged Mode):

[0068] * ul-AM-RLC configuration information: The ul-AM-RLC configuration information may include information on at least one of the length of the Sequence Number (e.g., sn-FieldLength), the size of the Poll retransmission timer (e.g., t-PollRetransmit), the threshold value of the number of Poll trigger PDUs (e.g., pollPDU), the threshold value of the Poll trigger Byte (e.g., pollByte), or the maximum number of retransmissions (e.g., maxRetxThreshold).

[0069] * dl-AM-RLC configuration information: The dl-AM-RLC configuration information may include information about at least one of the length of the Sequence Number (e.g., sn-FieldLength), the size of the Reassembly timer (e.g., t-Reassembly), or the size of the Status PDU prohibit timer (e.g., t-StatusProhibit).

[0070] - When the RLC layer device is set to UM (Unacknowledged Mode) Bi-Directional mode:

[0071] * ul-UM-RLC configuration information: ul-UM-RLC configuration information may include information about the length of the Sequence Number (e.g., sn-FieldLength).

[0072] * dl-UM-RLC configuration information: The dl-UM-RLC configuration information may include information about at least one of the length of the Sequence Number (e.g., sn-FieldLength), or the size of the Reassembly timer (e.g., t-Reassembly).

[0073] - When the RLC layer device is set to UM Uni-Directional-UL mode:

[0074] * ul-UM-RLC configuration information: ul-UM-RLC configuration information may include information about the length of the Sequence Number (e.g., sn-FieldLength).

[0075] - When the RLC layer device is set to UM Uni-Directional-DL mode:

[0076] * dl-UM-RLC configuration information: The dl-UM-RLC configuration information may include information about at least one of the length of the Sequence Number (e.g., sn-FieldLength), or the size of the Reassembly timer (e.g., t-Reassembly).

[0077] A terminal that has established an RRC connection can enter RRC_CONNECTED mode. The terminal can transmit an RRCSetupComplete message to the base station in step 310 (310).

[0078] If the base station does not know the capabilities of the terminal that is currently establishing a connection, or if it wants to determine the capabilities of the terminal, it can send a message (e.g., UECapabilityEnquiry) to the terminal inquiring about the capabilities of the terminal (315) at step 315.

[0079] The terminal may transmit a message reporting its capabilities (e.g., UECapabilityInformation) to the base station at step 320. The terminal capability reporting message may include an indicator indicating whether the terminal supports the low-latency RLC Polling function.

[0080] The base station can determine whether the terminal supports the low-latency RLC Polling function. If the terminal supports the low-latency RLC Polling function, the base station can transmit or deliver low-latency RLC Polling-related configuration information to the terminal via an RRC message (e.g., an RRCReconfiguration message (at least one of 335 or 350)).

[0081] The base station may transmit a SecurityModeCommand message (325) to the terminal in step 325 to set up security with the terminal. The terminal may transmit a SecurityModeComplete message (330) to the base station in step 330. When the security setting is completed, the base station may transmit an RRCReconfiguration message to the terminal in step 335 (335).

[0082] For example, the RRCReconfiguration message may contain configuration information (e.g., RadioBearerConfig) for each Radio Bearer (e.g., at least one of a DRB or SRB). The Radio Bearer configuration information may include an ID of each Radio Bearer, configuration information for the PDCP layer device of the Radio Bearer (e.g., PDCP-Config), an indicator indicating whether the Radio Bearer is a DAPS Bearer, etc.

[0083] For example, the RRCReconfiguration message may include, for each Cell Group (e.g., at least one of MCG or SCG), RLC Bearer configuration information (e.g., RLC-BearerConfig) belonging to the Cell Group. The RLC Bearer configuration information may include at least one of the following information:

[0084] - logicalChannelIdentity: Can indicate the LCID corresponding to the RLC Bearer and / or layer device.

[0085] - servedRadioBearer: May indicate a Radio Bearer ID associated with an RLC Bearer and / or a layer device. The Radio Bearer ID may indicate at least one of a specific DRB or SRB.

[0086] - rlc-Config: You can indicate the RLC layer parameter setting information of the RLC layer device of the RLC Bearer.

[0087] For example, the above rlc-Config may include at least one of the following configuration information:

[0088] - When the RLC layer device is set to AM (Acknowledged Mode):

[0089] * ul-AM-RLC configuration information: The ul-AM-RLC configuration information may include information on at least one of the length of the Sequence Number (e.g., sn-FieldLength), the size of the Poll retransmission timer (e.g., t-PollRetransmit), the threshold value of the number of Poll trigger PDUs (e.g., pollPDU), the threshold value of the Poll trigger Byte (e.g., pollByte), or the maximum number of retransmissions (e.g., maxRetxThreshold). For example, if the terminal supports low-latency RLC Polling, the configuration related to low-latency RLC Polling may be included.

[0090] * dl-AM-RLC configuration information: The dl-AM-RLC configuration information may include information about at least one of the length of the Sequence Number (e.g., sn-FieldLength), the size of the Reassembly timer (e.g., t-Reassembly), or the size of the Status PDU prohibit timer (e.g., t-StatusProhibit). For example, if the terminal supports low-latency RLC Polling, the configuration related to low-latency RLC Polling may be included.

[0091] - When the RLC layer device is set to UM (Unacknowledged Mode) Bi-Directional mode:

[0092] * ul-UM-RLC configuration information: ul-UM-RLC configuration information may include information about the length of the Sequence Number (e.g., sn-FieldLength).

[0093] * dl-UM-RLC configuration information: The dl-UM-RLC configuration information may include information about at least one of the length of the Sequence Number (e.g., sn-FieldLength), or the size of the Reassembly timer (e.g., t-Reassembly).

[0094] - When the RLC layer device is set to UM Uni-Directional-UL mode:

[0095] * ul-UM-RLC configuration information: ul-UM-RLC configuration information may include information about the length of the Sequence Number (e.g., sn-FieldLength).

[0096] - When the RLC layer device is set to UM Uni-Directional-DL mode:

[0097] * dl-UM-RLC configuration information: The dl-UM-RLC configuration information may include information about at least one of the length of the Sequence Number (e.g., sn-FieldLength), or the size of the Reassembly timer (e.g., t-Reassembly).

[0098] A typical data transmission process can be comprised of three steps: RRC connection setup, security setup, and DRB setup. The base station can transmit an RRCReconfiguration message to the terminal to configure, add, or change new settings (step 350).

[0099] For example, the RRCReconfiguration message may include configuration information (e.g., RadioBearerConfig) for each Radio Bearer (e.g., at least one of a DRB or SRB). The Radio Bearer configuration information may include an ID of each Radio Bearer, configuration information for the PDCP layer device of the Radio Bearer (e.g., PDCP-Config), an indicator indicating whether the Radio Bearer is a DAPS Bearer, etc.

[0100] For example, RRCReconfiguration may include, for each Cell Group (e.g., at least one of MCG or SCG), RLC Bearer configuration information (e.g., RLC-BearerConfig) belonging to the Cell Group. The RLC Bearer configuration information may include at least one of the following information:

[0101] - logicalChannelIdentity: Can indicate the LCID corresponding to the RLC Bearer and / or layer device.

[0102] - servedRadioBearer: May indicate a Radio Bearer ID associated with an RLC Bearer and / or a layer device. The Radio Bearer ID may indicate at least one of a specific DRB or SRB.

[0103] - rlc-Config: You can indicate the RLC layer parameter setting information of the RLC layer device of the RLC Bearer.

[0104] For example, rlc-Config may contain at least one of the following configuration information:

[0105] - When the RLC layer device is set to AM (Acknowledged Mode):

[0106] * ul-AM-RLC configuration information: The ul-AM-RLC configuration information may include information on at least one of the length of the Sequence Number (e.g., sn-FieldLength), the size of the Poll retransmission timer (e.g., t-PollRetransmit), the threshold value of the number of Poll trigger PDUs (e.g., pollPDU), the threshold value of the Poll trigger Byte (e.g., pollByte), or the maximum number of retransmissions (e.g., maxRetxThreshold). For example, if the terminal supports the low-latency RLC Polling, a configuration related to low-latency RPC Polling may be added.

[0107] * dl-AM-RLC configuration information: The dl-AM-RLC configuration information may include information about at least one of the length of the Sequence Number (e.g., sn-FieldLength), the size of the Reassembly timer (e.g., t-Reassembly), or the size of the Status PDU prohibit timer (e.g., t-StatusProhibit). For example, if the terminal supports low-latency RLC Polling, a configuration related to low-latency RLC Polling may be added.

[0108] - When the RLC layer device is set to UM (Unacknowledged Mode) Bi-Directional mode:

[0109] * ul-UM-RLC configuration information: ul-UM-RLC configuration information may include information about the Sequence Number length (e.g., sn-FieldLength).

[0110] *: The dl-UM-RLC configuration information may include information about at least one of the length of the Sequence Number (e.g., sn-FieldLength), or the size of the Reassembly timer (e.g., t-Reassembly).

[0111] - When the RLC layer device is set to UM Uni-Directional-UL mode:

[0112] * ul-UM-RLC configuration information: ul-UM-RLC configuration information may include information about the Sequence Number length (e.g., sn-FieldLength).

[0113] - When the RLC layer device is set to UM Uni-Directional-DL mode:

[0114] * dl-UM-RLC configuration information: The dl-UM-RLC configuration information may include information about at least one of the length of the Sequence Number (e.g., sn-FieldLength), or the size of the Reassembly timer (e.g., t-Reassembly).

[0115] In one embodiment of the present disclosure, the terminal can perform at least one of: configuring each Radio Bearer, configuring corresponding PDCP layer devices, configuring RLC Bearers and / or layer devices having associations with each Radio Bearer and / or PDCP layer device, establishing associations between RLC layer devices and PDCP layer devices, or transmitting and receiving data (for example, at least one of step 345 or step 355) by configuring Radio Bearer of an RRC message (for example, RRCReconfiguration). For example, when the base station configures a low-latency RLC Polling function in the terminal through an RRC message (for example, RRCReconfiguration), the terminal can perform low-latency RLC Polling during the process of transmitting and receiving data (for example, at least one of step 345 or step 355).

[0116] As an example of the present disclosure, among RLC SDUs in an RLC layer device, a delay-critical RLC SDU can be defined as follows.

[0117] - A delay-critical RLC SDU may mean an RLC SDU corresponding to a PDCP PDU indicated as delay-critical by PDCP (see TS 38.323).

[0118] For example, if a specific PDCP SDU in a PDCP layer device of a terminal is a delay-critical PDCP SDU, and if a PDCP Data PDU containing the PDCP SDU is delivered to a lower layer of the terminal (e.g., RLC), a delay-critical indication for the PDCP Data PDU may be transmitted, delivered, or provided to the lower layer of the terminal (e.g., RLC) through terminal internal signaling.

[0119] For example, a delay-critical PDCP SDU can be defined as follows:

[0120] - If the PDCP layer device-specific setting (e.g., pdu-SetDiscard) of the Radio Bearer of the terminal via RRC is not set, it may mean a PDCP SDU whose remaining time before the timer (e.g., discardTimer) expires is shorter than the time (e.g., remainingTimeThreshold) set by the base station via RRC for each LCG of the terminal. If the PDCP layer device-specific setting (e.g., pdu-SetDiscard) of the Radio Bearer of the terminal via RRC is set, it may mean a PDCP SDU belonging to a PDU Set that includes at least one PDCP SDU whose remaining time before the timer (e.g., discardTimer) expires is shorter than the time (e.g., remainingTimeThreshold) set by the base station via RRC for each LCG of the terminal.

[0121] For example, for a delay status report (e.g., Delay Status Report, hereinafter referred to as DSR) reported at the MAC layer, the PDCP and RLC layer devices of the terminal can calculate the delay-critical PDCP data size and the delay-critical RLC data size as follows.

[0122] For example, when calculating the Delay-Critical PDCP Data Volume, the terminal may include at least one of the following items of the PDCP layer device.

[0123] - Delay-critical Data-P1: For example, it can mean the delay-critical PDCP SDUs for which no PDCP Data PDUs have been constructed.

[0124] - Delay-critical Data-P2: This may mean, for example, the PDCP Data PDUs that contain the delay-critical PDCP SDUs and have not been submitted to lower layers (e.g., RLC).

[0125] - Delay Critical Data-P3: For example, it can mean PDCP Control PDUs.

[0126] - Delay Critical Data-P4: For example, for AM DRBs, it may mean the PDCP SDUs to be retransmitted according to clause 5.1.2 and clause 5.13 of TS 38.323.

[0127] - Delay Critical Data-P5: For example, for AM DRBs, it may mean the PDCP Data PDUs to be retransmitted according to clause 5.5 of TS 38.323.

[0128] For example, when calculating the Delay-Critical RLC Data Volume, the terminal may include at least one of the following items of the RLC layer device.

[0129] - Delay-critical Data-R1: For example, it may mean at least one of delay-critical RLC SDUs and delay-critical RLC SDU segments that have not yet been included in an RLC data PDU.

[0130] - Delay-critical Data-R2: This may mean RLC Data PDUs pending for initial transmission, and containing at least one delay-critical RLC SDU or a delay-critical RLC SDU segment, for example.

[0131] - Delay Critical Data-R3: For example, if the RLC layer device is in AM mode, this may mean RLC data PDUs that are pending for retransmission (RLC AM).

[0132] - Delay Critical Data-R4: For example, if a STATUS PDU is triggered, and the t-StatusProhibit timer is not running or has expired, the terminal can predict the size of the STATUS PDU to be transmitted at the next transmission opportunity (e.g., Transmission Opportunity) and include it in the delay critical RLC data size.

[0133] FIG. 4 is a diagram illustrating a procedure for performing RLC Polling of an RLC layer device of a terminal according to an embodiment of the present disclosure.

[0134] Referring to FIG. 4, a terminal in an RRC_CONNECTED state can transmit an RLC PDU to a base station via an uplink (UL). For example, when a specific RLC layer device of the terminal is set to AM mode, the RLC layer device of the terminal can request a reception status for an AM Data (AMD) PDU transmitted by the terminal to a corresponding RLC layer device of the base station. The reception status request for the PDU can be transmitted or forwarded to the base station by the RLC layer device of the terminal setting the P (Poll) bit of the RLC header of the specific AMD PDU to 1. The base station can transmit the reception status of the AMD PDU transmitted by the RLC layer device of the terminal to the terminal via a STATUS PDU. The RLC layer device of the terminal can perform retransmission for an AMD PDU that the corresponding RLC layer device of the base station failed to receive (e.g., received a NACK).

[0135] The RLC layer device of the terminal can request a STATUS PDU from the base station (e.g., perform polling or polling) by setting the P (Poll) bit of the header of a specific AMD PDU to 1 when a specific polling trigger condition is satisfied. Polling delay that may occur before a specific polling trigger condition is satisfied may lead to a retransmission delay.

[0136] For example, the corresponding RLC layer device of the base station may fail to receive AMD PDU 1 (SN=1, 400) transmitted by the RLC layer device of the terminal. In order for retransmission (440) due to reception failure to occur, the Polling trigger condition (420) of the RLC layer device of the terminal must be satisfied, the P bit of a specific AMD PDU (SN=N+1, 425) must be set to 1 and transmitted or forwarded to the base station, a STATUS PDU must be triggered in the corresponding RLC layer device of the base station due to the Polling, and a STATUS PDU (430) including reception failure for AMD PDU 1 must be forwarded to the terminal.

[0137] If polling is delayed, retransmission of AMD PDUs that fail to be received may be delayed. If retransmission of delay-critical data is delayed, retransmission of data that exceeds at least one of the Packet Delay Budget (PDB) or PDU Set Delay Budget (PSDB) of the delay-critical data may become meaningless. In addition, user service quality may be degraded. The low-latency RLC polling method proposed in the present disclosure proposes a method and device for reducing polling delay and retransmission delay for delay-critical data.

[0138] In one embodiment of the present disclosure, the base station may configure at least one of a threshold value (e.g., at least one of pollDelayCriticalPDU or pollDelayCriticalByte) or a new polling retransmission timer (e.g., t-pollDelayCriticalRetransmit) used for a new polling trigger in an RRC message (e.g., RRCReconfiguration (e.g., at least one of 335 or 350 of FIG. 3)) or a new polling retransmission timer (e.g., t-pollDelayCriticalRetransmit) for delay-critical RLC data to the terminal if the terminal supports enhanced RLC functionality for delay-critical data.

[0139] In one embodiment of the present disclosure, the AM RLC layer device may use at least one of a new Polling trigger variable (e.g., at least one of DELAY_CRITICAL_PDU_WITHOUT_POLL, or DELAY_CRITICAL_BYTE_WITHOUT_POLL), or a new POLL_SN variable (e.g., DELAY_CRITICAL_POLL_SN) for delay critical RLC data.

[0140] In one embodiment of the present disclosure, the variables, Counter, and Timer of each AM RLC layer device may mean at least one of the following.

[0141] POLL_SN - Poll send state variable

[0142] - This state variable holds the value of the highest SN of the AMD PDU among the AMD PDUs submitted to lower layer when POLL_SN is set according to clause 5.3.3.2 of TS38.322. It is initially set to 0.

[0143] DELAY_CRITICAL_POLL_SN - Poll send state variable for delay-critical data

[0144] - This state variable holds the value of the highest SN of the delay-critical AMD PDU among the delay-critical AMD PDUs submitted to lower layer when DELAY_CRITICAL_POLL_SN is set according to TS38.322. It is initially set to 0.

[0145] PDU_WITHOUT_POLL - Counter

[0146] - This counter is initially set to 0. It counts the number of AMD PDUs sent since the most recent poll bit was transmitted.

[0147] BYTE_WITHOUT_POLL - Counter

[0148] - This counter is initially set to 0. It counts the number of data bytes sent since the most recent poll bit was transmitted.

[0149] DELAY_CRITICAL_PDU_WITHOUT_POLL - Counter

[0150] - This counter is initially set to 0. It counts the number of delay-critical AMD PDUs sent since the most recent poll bit was transmitted.

[0151] DELAY_CRITICAL_BYTE_WITHOUT_POLL - Counter

[0152] - This counter is initially set to 0. It counts the number of data bytes sent by delay-critical AMD PDUs since the most recent poll bit was transmitted.

[0153] t-PollRetransmit

[0154] - This timer is used by the transmitting side of an AM RLC entity in order to retransmit a poll (see clause 5.3.3 of TS 38.322).

[0155] t-PollDelayCriticalRetransmit

[0156] - This timer is used by the transmitting side of an AM RLC entity in order to retransmit a poll triggered by delay-critical AMD PDU.

[0157] For example, a Delay-Critical AMD PDU may indicate at least one of the following cases:

[0158] - It may indicate an AMD PDU containing at least one of a delay-critical RLC SDU or a delay-critical RLC SDU Segment.

[0159] In one embodiment of the present disclosure, a condition for triggering polling in an RLC layer device operating in AM mode may be when at least one of a new polling trigger threshold (e.g., at least one of pollDelayCriticalPDU or pollDelayCriticalByte), a setting indicating a low-latency RLC polling function for delay-critical data, and / or a new polling retransmission timer (e.g., t-pollDelayCriticalRetransmit) is set. However, the above-mentioned conditions correspond to one embodiment. Among the above embodiments, there may be a combination of multiple embodiments or conditions, and the combination may be considered as a new embodiment.

[0160] The following discloses poll trigger methods that are performed when the above conditions are satisfied. The following method corresponds to one embodiment, and among the embodiments below, there may be a combination of multiple embodiments or methods, and such combinations may be considered new embodiments.

[0161] Poll Trigger Method 1:

[0162] When a Transmission Opportunity is received or notified from a lower layer, an RLC layer device may perform at least one of the following actions for each AMD PDU it delivers to the lower layer.

[0163] - If the AMD PDU contains an untransmitted RLC SDU or an RLC SDU Segment that contains a Byte Segment that was never transmitted:

[0164] * The PDU_WITHOUT_POLL variable can be increased by 1.

[0165] * The BYTE_WITHOUT_POLL variable can be incremented by the number of new (e.g., never-before-sent) bytes contained in the Data Field Element in the Data field of the AMD PDU.

[0166] * if PDU_WITHOUT_POLL >= pollPDU; or

[0167] * If BYTE_WITHOUT_POLL >= pollByte

[0168] - Polling method 1 can be performed.

[0169] When an AMD PDU contains a Poll, the transmitting AM RLC layer device may perform at least one of the following actions.

[0170] - Set the P field of AMD PDU to 1

[0171] - Set PDU_WITHOUT_POLL to 0

[0172] - Set BYTE_WITHOUT_POLL to 0

[0173] When transmitting an AMD PDU including a Poll to a lower layer, the transmitting AM RLC layer device may perform at least one of the following actions.

[0174] - The POLL_SN variable can be set to the SN of the AMD PDU with the largest SN among the AMD PDUs passed to the lower layer.

[0175] - If the t-PollRetransmit timer is not running:

[0176] * The t-PollRetransmit timer can be started.

[0177] - Otherwise (e.g. if t-PollRetransmit is running):

[0178] * The t-PollRetransmit timer can be restarted.

[0179] Poll Trigger Method 2:

[0180] When a Transmission Opportunity is received or notified from a lower layer, an RLC layer device may perform at least one of the following actions for each AMD PDU it delivers to the lower layer.

[0181] - If the AMD PDU contains a delay-critical RLC SDU or a delay-critical RLC SDU Segment that has never been transmitted, including a Byte Segment that has never been transmitted:

[0182] * The PDU_WITHOUT_POLL variable can be increased by 1.

[0183] * The BYTE_WITHOUT_POLL variable can be incremented by the number of new (e.g., never-before-sent) bytes contained in the Data Field Element in the Data field of the AMD PDU.

[0184] * if PDU_WITHOUT_POLL >= pollDelayCriticalPDU; or

[0185] * if PDU_WITHOUT_POLL >= pollPDU; or

[0186] * if BYTE_WITHOUT_POLL >= pollDelayCriticalByte; or

[0187] * If BYTE_WITHOUT_POLL >= pollByte:

[0188] - Polling option 2-1: Polling method 1 can be performed.

[0189] - Polling option 2-2: Polling method 2 can be performed.

[0190] When a Delay-Critical AMD PDU contains a Poll, the transmitting AM RLC layer device may perform at least one of the following actions.

[0191] - Set the P field of AMD PDU to 1

[0192] - Set PDU_WITHOUT_POLL to 0

[0193] - Set BYTE_WITHOUT_POLL to 0

[0194] When delivering a Delay-Critical AMD PDU including a Poll to a lower layer, the transmitting AM RLC layer device may perform at least one of the following actions.

[0195] - Poll SN option 2-1: The POLL_SN variable can be set to the SN of the AMD PDU with the largest SN among the AMD PDUs passed to the lower layer.

[0196] - Poll SN option 2-2: The DELAY_CRITICAL_POLL_SN variable can be set to the highest SN among the Delay-Critical AMD PDUs passed to the lower layer. If the polling is triggered by Delay-Critical data, it can be considered as requesting an ACK or NACK status for the Delay-Critical data.

[0197] - Poll retx timer option 2-1:

[0198] * If the t-PollRetransmit timer is not running:

[0199] - The t-PollRetransmit timer can be started.

[0200] * Otherwise (e.g. if t-PollRetransmit is running):

[0201] - The t-PollRetransmit timer can be restarted.

[0202] - Poll retx timer option 2-2:

[0203] * If the t-PollDelayCriticalRetransmit timer is not running:

[0204] - The t-PollDelayCriticalRetransmit timer can be started.

[0205] * Otherwise (e.g., if t-PollDelayCriticalRetransmit is running):

[0206] - The t-PollDelayCriticalRetransmit timer can be restarted.

[0207] * Effect: The t-PollDelayCriticalRetransmit timer may be a timer for retransmitting polling triggered by delay-critical RLC AMD PDUs (e.g., when a requested STATUS PDU does not arrive). When the timer expires, the RLC layer device may retransmit polling for delay-critical RLC AMD PDUs.

[0208] Poll Trigger Method 3:

[0209] When a Transmission Opportunity is received or notified from a lower layer, an RLC layer device may perform at least one of the following actions for each AMD PDU it delivers to the lower layer.

[0210] - If the AMD PDU contains a delay-critical RLC SDU or a delay-critical RLC SDU Segment that has never been transmitted, including a Byte Segment that has never been transmitted:

[0211] * The DELAY_CRITICAL_PDU_WITHOUT_POLL variable can be increased by 1. For example, the PDU_WITHOUT_POLL variable can be increased by 1. For example, PDU_WITHOUT_POLL may not be increased.

[0212] * The DELAY_CRITICAL_BYTE_WITHOUT_POLL variable can be incremented by the number of new (e.g., never-before-sent) bytes contained in the Data Field Element of the Data field of the AMD PDU. For example, the BYTE_WITHOUT_POLL variable can be incremented by the number of new (e.g., never-before-sent) bytes contained in the Data Field Element of the Data field of the AMD PDU. For example, the BYTE_WITHOUT_POLL variable can be left unincremented.

[0213] * if DELAY_CRITICAL_PDU_WITHOUT_POLL >= pollDelayCriticalPDU; or

[0214] * if PDU_WITHOUT_POLL >= pollPDU; or

[0215] * If DELAY_CRITICAL_BYTE_WITHOUT_POLL >= pollDelayCriticalByte or

[0216] * If BYTE_WITHOUT_POLL >= pollByte:

[0217] - Polling option 3-1: Polling method 1 can be performed.

[0218] - Polling option 3-2: Polling method 2 can be performed.

[0219] When including a Poll in a Delay-Critical AMD PDU, the transmitting AM RLC layer device may perform at least one of the following actions.

[0220] - The P field of AMD PDU can be set to 1.

[0221] - DELAY_CRITICAL_PDU_WITHOUT_POLL can be set to 0. For example, PDU_WITHOUT_POLL can be set to 0. For example, PDU_WITHOUT_POLL can be changed (e.g., increased or decreased) or set to 0 (e.g., reset to 0).

[0222] - DELAY_CRITICAL_BYTE_WITHOUT_POLL can be set to 0. For example, BYTE_WITHOUT_POLL can be set to 0. For example, BYTE_WITHOUT_POLL can be changed (e.g., incremented or decremented) or set to 0 (e.g., reset to 0).

[0223] When delivering a Delay-Critical AMD PDU including a Poll to a lower layer, the transmitting AM RLC layer device may perform at least one of the following actions.

[0224] - Poll SN option 3-1: The POLL_SN variable can be set to the SN of the AMD PDU with the largest SN among the AMD PDUs passed to the lower layer.

[0225] - Poll SN option 3-2: The DELAY_CRITICAL_POLL_SN variable can be set to the highest SN among the Delay-Critical AMD PDUs passed to the lower layer. If the polling is triggered by Delay-Critical data, it can be considered as a request for ACK or NACK status for the Delay-Critical data.

[0226] - Poll retx timer option 3-1:

[0227] * If the t-PollRetransmit timer is not running:

[0228] - The t-PollRetransmit timer can be started.

[0229] * Otherwise (e.g. if t-PollRetransmit is running):

[0230] - The t-PollRetransmit timer can be restarted.

[0231] - Poll retx timer option 3-2:

[0232] * If the t-PollDelayCriticalRetransmit timer is not running:

[0233] - The t-PollDelayCriticalRetransmit timer can be started.

[0234] * Otherwise (e.g., if t-PollDelayCriticalRetransmit is running):

[0235] - The t-PollDelayCriticalRetransmit timer can be restarted.

[0236] * Effect: The t-PollDelayCriticalRetransmit timer may be a timer for retransmitting polling triggered by delay-critical RLC AMD PDUs (e.g., when a requested STATUS PDU does not arrive). When the timer expires, the RLC layer device may retransmit polling for delay-critical RLC AMD PDUs.

[0237] Poll Trigger Method 4:

[0238] When notified of a Transmission Opportunity from a lower layer, an RLC layer device may perform at least one of the following actions for each AMD PDU it forwards to the lower layer.

[0239] - If, after transmitting a specific AMD PDU, the transmission buffer and the retransmission buffer are empty (at least one of the RLC SDUs or RLC SDU Segments that has already been transmitted but is waiting for an Acknowledgement may be excluded); or

[0240] - If a new RLC SDU cannot be created after transmitting the corresponding AMD PDU (for example, if Window Stalling occurs):

[0241] * Polling method 1 can be performed.

[0242] * If there are RLC SDUs or RLC SDU Segments that have already been transmitted but are waiting for Acknowledgement, and at least one of them is a delay-critical RLC SDU or RLC SDU Segment, Polling Method 1 or Polling Method 2 can be performed.

[0243] When an AMD PDU contains a Poll, the transmitting RLC layer device may perform at least one of the following actions:

[0244] - The P field of AMD PDU can be set to 1.

[0245] - PDU_WITHOUT_POLL can be set to 0. For example, DELAY_CRITICAL_PDU_WITHOUT_POLL can be set to 0. For example, DELAY_CRITICAL_PDU_WITHOUT_POLL can be changed (e.g., increased or decreased) or set to 0 (e.g., reset to 0).

[0246] - BYTE_WITHOUT_POLL can be set to 0. For example, DELAY_CRITICAL_BYTE_WITHOUT_POLL can be set to 0. For example, DELAY_CRITICAL_BYTE_WITHOUT_POLL can be changed (e.g., increased or decreased) or set to 0 (e.g., reset to 0).

[0247] Poll Trigger Method 5:

[0248] The base station can set a specific AM mode RLC layer device of the terminal to a setting 1 (e.g., pollForDelayCritical) via an RRC message (e.g., RRCReconfiguration). For example, pollForDelayCritical can be set to 1-bit, BOOLEAN, or other forms.

[0249] In one embodiment of the present disclosure, when notified of a transmission opportunity from a lower layer, an RLC layer device may perform at least one of the following actions for each AMD PDU transmitted to the lower layer.

[0250] - If the AMD PDU contains at least one untransmitted delay-critical RLC SDU or delay-critical RLC SDU Segment that contains a Byte Segment that was never transmitted:

[0251] - For example, if pollForDelayCritical is set, the terminal

[0252] * You can perform Polling Method 1. Or

[0253] * Polling method 2 can be performed.

[0254] - For example, regardless of whether pollForDelayCritical is set, the terminal

[0255] * You can perform Polling Method 1. Or

[0256] * Polling method 2 can be performed.

[0257] When including a Poll in a Delay-Critical AMD PDU, the transmitting AM RLC layer device may perform at least one of the following actions.

[0258] - The P field of AMD PDU can be set to 1.

[0259] - DELAY_CRITICAL_PDU_WITHOUT_POLL can be set to 0. For example, PDU_WITHOUT_POLL can be set to 0. For example, PDU_WITHOUT_POLL can be changed (e.g., increased or decreased) or set to 0 (e.g., reset to 0).

[0260] - Set DELAY_CRITICAL_BYTE_WITHOUT_POLL to 0. For example, BYTE_WITHOUT_POLL can be set to 0. For example, BYTE_WITHOUT_POLL may not be changed (e.g., incremented or decremented) or set to 0 (e.g., reset to 0).

[0261] When delivering a Delay-Critical AMD PDU including a Poll to a lower layer, the transmitting AM RLC layer device may perform at least one of the following actions.

[0262] - Poll SN option 5-1: The POLL_SN variable can be set to the SN of the AMD PDU with the largest SN among the AMD PDUs passed to the lower layer.

[0263] - Poll SN option 5-2: The DELAY_CRITICAL_POLL_SN variable can be set to the highest SN among the Delay-Critical AMD PDUs passed to the lower layer. If the polling is triggered by Delay-Critical data, the polling can be considered as requesting an ACK or NACK status for the Delay-Critical data.

[0264] - Poll retx timer option 5-1:

[0265] * If the t-PollRetransmit timer is not running:

[0266] - The t-PollRetransmit timer can be started.

[0267] * Otherwise (e.g. if t-PollRetransmit is running):

[0268] - The t-PollRetransmit timer can be restarted.

[0269] - Poll retx timer option 5-2:

[0270] * If the t-PollDelayCriticalRetransmit timer is not running:

[0271] - The t-PollDelayCriticalRetransmit timer can be started.

[0272] * Otherwise (e.g., if t-PollDelayCriticalRetransmit is running):

[0273] - The t-PollDelayCriticalRetransmit timer can be restarted.

[0274] * Effect: The t-PollDelayCriticalRetransmit timer can be used to indicate a timer for retransmitting polling triggered by delay-critical RLC AMD PDUs (e.g., when a requested STATUS PDU does not arrive). When the timer expires, polling for delay-critical RLC AMD PDUs can be retransmitted.

[0275] FIG. 5 is a diagram illustrating an RLC Polling procedure in an AM RLC layer device according to an embodiment of the present disclosure.

[0276] Referring to FIG. 5, the AM RLC layer device (510) can include a PDCP PDU received from a PDCP (500) layer device in an AMD PDU and forward it to a lower layer. For example, the buffer held by the AM RLC layer device can mean any one of the buffers below.

[0277] - Buffer 1: Initial transmission buffer (520) that stores AMD PDUs waiting for initial transmission.

[0278] - Buffer 2: An ACK or NACK waiting buffer (530) that stores at least one of the AM RLC SDU or AMD PDU waiting for an Acknowledgement from the receiving RLC layer device that received it after transmission.

[0279] - Buffer 3: A retransmission buffer (540) that stores at least one of the AM RLC SDU or AMD PDU for which a NACK has been received from a receiving RLC layer device for retransmission.

[0280] When an AMD PDU is delivered to a lower layer, it may not be a delay-critical AMD PDU. After the initial transmission, while waiting for an Acknowledgement, an AMD PDU may transition to at least one of a delay-critical RLC SDU or an AMD PDU. Therefore, a polling method triggered by at least one of a delay-critical RLC SDU or an AMD PDU in Buffer 2 may be required.

[0281] In one embodiment of the present disclosure, a base station can set configuration 2 (e.g., pollForPendingPDU) to a specific AM RLC layer device of a terminal via an RRC message (e.g., RRCReconfiguration). For example, an AM RLC layer device with pollForPendingPDU set can trigger polling by at least one of delay-critical AM RLC SDUs or AMD PDUs stored in buffer 2. For example, an AM RLC layer device with pollForPendingPDU set can perform at least one of the following embodiments.

[0282] Poll Trigger Method 6:

[0283] In one embodiment of the present disclosure, an AM RLC layer device with pollForPendingPDU set may perform at least one of the following actions for each RLC SDU or each RLC SDU Segment transmitted while waiting for an Acknowledgement (e.g., in buffer 2).

[0284] - If at least one of the RLC SDU or RLC SDU Segments becomes a delay-critical RLC SDU or a delay-critical RLC SDU Segment:

[0285] * You can increase the DELAY_CRITICAL_PDU_WITHOUT_POLL variable by 1.

[0286] * The DELAY_CRITICAL_BYTE_WITHOUT_POLL variable can be increased by the size (in bytes) of at least one of the corresponding RLC SDU or the corresponding RLC SDU Segment.

[0287] -*If DELAY_CRITICAL_PDU_WITHOUT_POLL >= pollDelayCriticalPDU; or

[0288] * If DELAY_CRITICAL_BYTE_WITHOUT_POLL >= pollDelayCriticalByte or

[0289] - The AMD PDU passed to the next lower layer may contain a Poll.

[0290] If buffer 1 (520) and buffer 3 (540) are empty at least at one of the above poll trigger times or at the time of receiving the next transmission opportunity from the lower layer (at this time, at least one of the RLC SDU or RLC SDU Segment that has already been transmitted but is waiting for an Acknowledgement may be excluded), the terminal

[0291] - Option 1: Among the Delay-Critical RLC SDUs or RLC SDU Segments for which an ACK has not yet been received, at least one Delay-Critical RLC SDU or RLC SDU Segment with the shortest remaining PDCP discardTimer time (i.e., the time remaining until PDCP discardTimer expires) (wherein the shortest time may not be 0) can be retransmitted.

[0292] - Option 2: At least one of the Delay-Critical RLC SDUs or RLC SDU Segments that triggered the Poll can be retransmitted.

[0293] When an AMD PDU contains a Poll triggered by at least one of a delay-critical RLC SDU or an RLC SDU Segment, the transmitting AM RLC layer device may perform at least one of the following actions:

[0294] - The P field of AMD PDU can be set to 1.

[0295] - DELAY_CRITICAL_PDU_WITHOUT_POLL can be set to 0. For example, PDU_WITHOUT_POLL can be set to 0. For example, PDU_WITHOUT_POLL can be changed (e.g., increased or decreased) or set to 0 (e.g., reset to 0).

[0296] - DELAY_CRITICAL_BYTE_WITHOUT_POLL can be set to 0. For example, BYTE_WITHOUT_POLL can be set to 0. For example, BYTE_WITHOUT_POLL can be set to 0 without changing (e.g., incrementing or decrementing) or being set to 0 (e.g., being reset to 0).

[0297] When delivering an AMD PDU to a lower layer that includes a Poll triggered by at least one of a delay-critical RLC SDU / RLC SDU Segment or an AMD PDU, the transmitting AM RLC layer device may perform at least one of the following actions:

[0298] - Poll SN option 6-1: The POLL_SN variable can be set to the SN of the AMD PDU with the largest SN among the AMD PDUs passed to the lower layer.

[0299] - Poll SN option 6-2: The DELAY_CRITICAL_POLL_SN variable can be set to the highest SN among the Delay-Critical AMD PDUs passed to the lower layer. If the polling is triggered by Delay-Critical data, it can be considered as requesting an ACK or NACK status for the Delay-Critical data.

[0300] - Poll retx timer option 6-1:

[0301] * If the t-PollRetransmit timer is not running:

[0302] - The t-PollRetransmit timer can be started.

[0303] * Otherwise (e.g. if t-PollRetransmit is running):

[0304] - The t-PollRetransmit timer can be restarted.

[0305] - Poll retx timer option 6-2:

[0306] * If the t-PollDelayCriticalRetransmit timer is not running:

[0307] - The t-PollDelayCriticalRetransmit timer can be started.

[0308] * Otherwise (e.g. t-PollDelayCriticalRetransmit is running):

[0309] - The t-PollDelayCriticalRetransmit timer can be restarted.

[0310] * Effect: The t-PollDelayCriticalRetransmit timer can be used to indicate a timer for retransmitting polling triggered by delay-critical RLC AMD PDUs (e.g., when a requested STATUS PDU does not arrive). When the timer expires, polling for delay-critical RLC AMD PDUs can be retransmitted.

[0311] Poll Trigger Method 7:

[0312] In one embodiment of the present disclosure, an AM RLC layer device with pollForPendingPDU set may perform at least one of the following actions for each RLC SDU or each RLC SDU Segment transmitted while waiting for an Acknowledgement (e.g., in buffer 2).

[0313] - Option 1: If at least one of the RLC SDUs or RLC SDU Segments becomes a delay-critical RLC SDU or a delay-critical RLC SDU Segment:

[0314] - Option 2: If there is at least one delay-critical RLC SDU or RLC SDU Segment in buffer 2:

[0315] * The AMD PDU passed to the next lower layer may contain a Poll.

[0316] If buffer 1 (520) and buffer 3 (540) are empty at least at one of the above poll trigger time or the time when the next transmission opportunity is notified from the lower layer (at this time, at least one of the RLC SDU or RLC SDU Segment that has already been transmitted but is waiting for an Acknowledgement may be excluded), the terminal

[0317] - Option 1: Among the Delay-Critical RLC SDUs or RLC SDU Segments for which an Ack has not yet been received, at least one Delay-Critical RLC SDU or RLC SDU Segment with the shortest remaining PDCP discardTimer time (i.e., the time remaining until PDCP discardTimer expires) (wherein the shortest time may not be 0) can be retransmitted.

[0318] - Option 2: At least one of the Delay-Critical RLC SDUs or RLC SDU Segments that triggered the Poll can be retransmitted.

[0319] When an AMD PDU includes a Poll triggered by at least one of a delay-critical RLC SDU or an RLC SDU Segment, the transmitting AM RLC layer device may perform at least one of the following actions:

[0320] - The P field of AMD PDU can be set to 1.

[0321] - DELAY_CRITICAL_PDU_WITHOUT_POLL can be set to 0. For example, PDU_WITHOUT_POLL can be set to 0. For example, PDU_WITHOUT_POLL can be changed (e.g., increased or decreased) or set to 0 (e.g., reset to 0).

[0322] - DELAY_CRITICAL_BYTE_WITHOUT_POLL can be set to 0. For example, BYTE_WITHOUT_POLL can be set to 0. For example, BYTE_WITHOUT_POLL can be set to 0 without changing (e.g., incrementing or decrementing) or being set to 0 (e.g., being reset to 0).

[0323] When delivering an AMD PDU to a lower layer that includes a Poll triggered by at least one of a delay-critical RLC SDU, an RLC SDU Segment, or an AMD PDU, the transmitting AM RLC layer device may perform at least one of the following actions:

[0324] - Poll SN option 6-1: The POLL_SN variable can be set to the SN of the AMD PDU with the largest SN among the AMD PDUs passed to the lower layer.

[0325] - Poll SN option 6-2: The DELAY_CRITICAL_POLL_SN variable can be set to the highest SN among the Delay-Critical AMD PDUs passed to the lower layer. If the polling is triggered by Delay-Critical data, it can be considered as requesting an ACK or NACK status for the Delay-Critical data.

[0326] - Poll retx timer option 6-1:

[0327] * If the t-PollRetransmit timer is not running:

[0328] - The t-PollRetransmit timer can be started.

[0329] * Otherwise (e.g. if t-PollRetransmit is running):

[0330] - The t-PollRetransmit timer can be restarted.

[0331] - Poll retx timer option 6-2:

[0332] * If the t-PollDelayCriticalRetransmit timer is not running:

[0333] - The t-PollDelayCriticalRetransmit timer can be started.

[0334] * Otherwise (e.g., if t-PollDelayCriticalRetransmit is running):

[0335] - The t-PollDelayCriticalRetransmit timer can be restarted.

[0336] * Effect: The t-PollDelayCriticalRetransmit timer can be used to indicate a timer for retransmitting polling triggered by delay-critical RLC AMD PDUs (e.g., when a requested STATUS PDU does not arrive). When the timer expires, polling for delay-critical RLC AMD PDUs can be retransmitted.

[0337] In one embodiment of the present disclosure, when the t-PollDelayCriticalRetransmit timer expires, the transmitting AM RLC layer device may perform at least one of the following operations.

[0338] - If the initial transmission buffer and the retransmission buffer are empty (at least one of the RLC SDUs or RLC SDU Segments that has already been transmitted but is waiting for an Acknowledgement may be excluded); or

[0339] - When a new RLC SDU or RLC SDU Segment cannot be created (for example, when Window Stalling occurs).

[0340] * Option 1: The RLC SDU with the largest SN among the RLC SDUs delivered to the lower layer can be retransmitted.

[0341] * Option 2: Any RLC SDU that has not yet received an ack can be retransmitted.

[0342] * Option 3: Among the Delay-Critical RLC SDUs for which an ack has not yet been received, the Delay-Critical RLC SDU with the shortest remaining discardTimer time can be retransmitted.

[0343] - Poll can be transmitted by including it in AMD PDU.

[0344] FIG. 6a, FIG. 6b, FIG. 6c, and FIG. 6d are diagrams illustrating an AM RLC PDU format according to an embodiment of the present disclosure.

[0345] Referring to FIGS. 6a, 6b, 6c, and 6d, Polling method 1 can be performed as follows.

[0346] Polling Method 1: In the existing AMD PDU format, polling can be indicated by setting the P field of the RLC header (e.g., at least one of 600, 610, 620, or 630) to 1.

[0347] Referring to FIGS. 6a, 6b, 6c, and 6d, Polling method 2 can be performed as follows.

[0348] Polling Method 2

[0349] - Option 2-1: Polling triggered by delay-critical RLC data (e.g., at least one of RLC SDU, SDU Segment, or AMD PDU) can be indicated by setting at least one of the RLC header Reserved Bits (e.g., at least one of 640, 650, 660, or 670) in the AMD PDU format to 1.

[0350] - Option 2-2: A new AMD PDU format can be introduced, which allows each polling to be indicated by two P bits (e.g., at least one of P1 or P2) in the RLC header of that format. The two P bits can be used to distinguish between polling due to delay-critical RLC data and polling without such data.

[0351] - Option 2-3: A new RLC Control PDU can be introduced to indicate polling by delay-critical RLC data.

[0352] In one embodiment of the present disclosure, an AM RLC layer device may transmit a STATUS PDU to a counterpart AM RLC layer device to provide at least one of Ack or Nack information for a received RLC SDU.

[0353] In one embodiment of the present disclosure, the condition for generating a STATUS report trigger may be at least one of the following conditions.

[0354] - When a poll is received by the aforementioned polling method 1 from the counterpart AM RLC layer device:

[0355] * If the SN of the AMD PDU received from the lower layer is x and the P field is set to 1, the receiving AM RLC layer device

[0356] - Case 1: If the AMD PDU is discarded according to section 5.2.3.2.2 of TS38.322, or

[0357] - Case 2: If x < RX_Highest_Status or x >= RX_Next + AM_Window_Size

[0358] - A STATUS report can be triggered. The trigger can be immediate.

[0359] - Case 3: If not (i.e. neither case 1 nor case 2):

[0360] - You can delay the STATUS report trigger until x < RX_Highest_Status or x >= RX_Next + AM_Window_Size.

[0361] - When a Poll is received from the opposing AM RLC layer device by Polling Method 2 (e.g. by delay critical RLC data):

[0362] * A STATUS report can be triggered. The trigger can be immediate.

[0363] * For example, a STATUS PDU can be generated and delivered to the lower layer at the first transmission opportunity indicated by the lower layer, regardless of whether the t-StatusProhibit timer is running.

[0364] - If a failure to receive an AMD PDU is detected:

[0365] * The receiving AM RLC layer device can trigger a STATUS report when the t-Reassembly timer expires.

[0366] In one embodiment of the present disclosure, upon receiving a STATUS report, an AM RLC layer device may perform at least one of the following operations.

[0367] - If the STATUS report contains at least one of the ack (positive) or nack (negative) information for the RLC SDU corresponding to POLL_SN:

[0368] * For example, if the t-PollRetransmit timer is running, the t-PollRetransmit timer can be stopped and reset. Or, for example, if the t-PollDelayCriticalRetransmit timer is running, the t-PollDelayCriticalRetransmit timer can be stopped and reset.

[0369] - If the STATUS report contains at least one of the ack (positive) or nack (negative) information for the RLC SDU corresponding to the aforementioned DELAY_CRTICAL_POLL_SN:

[0370] * For example, if the t-PollRetransmit timer is running, the t-PollRetransmit timer can be stopped and reset. Or, for example, if the t-PollDelayCriticalRetransmit timer is running, the t-PollDelayCriticalRetransmit timer can be stopped and reset.

[0371] In one embodiment of the present disclosure, an AM RLC layer device may perform a retransmission for RLC data when delay-critical RLC data (e.g., at least one of an RLC SDU, an RLC SDU Segment, or an AMD PDU) occurs in buffer 2. The RLC layer device may perform a blind retransmission for the delay-critical data even without a reception feedback (e.g., at least one of an ack or a nack) for the corresponding RLC data (e.g., at least one of an RLC SDU, an RLC SDU Segment, or an AMD PDU).

[0372] In one embodiment of the present disclosure, blind retransmission may mean an operation of retransmitting at least one of an RLC SDU, SDU Segment, or AMD PDU before receiving an ACK / NACK feedback for at least one of the already transmitted RLC SDU, SDU Segment, or AMD PDU through a Status PDU. For example, the base station may configure, via an RRC message (e.g., an RRCReconfiguration message), whether the corresponding or associated RLC layer device will perform blind retransmission (or perform blind retransmission by setting a blind retransmission-related timer or counter value) for each RLC / PDCP / MAC / LCH / LCG / Bearer. For example, at least one RLC SDU, SDU Segment, or AMD PDU that performs a blind retransmission may be transmitted (or retransmitted) with priority over at least one other RLC SDU, SDU Segment, or AMD PDU. For example, an AM RLC layer device may add a Poll to an AMD PDU that performs a blind retransmission, or may request a Status PDU by setting the P field to 1.

[0373] In one embodiment of the present disclosure, after an AM RLC layer device delivers or transmits at least one of an RLC SDU, an SDU Segment, or an AMD PDU to or through a lower layer (MAC), or after at least one of the corresponding RLC SDU, SDU Segment, or AMD PDU arrives (or is generated) at the RLC layer, the AM RLC layer device may start a specific timer (e.g., a blind retransmission timer). If, by the time the blind retransmission timer expires, no ACK / NACK feedback via a Status PDU is received for at least one of the corresponding RLC SDU, SDU Segment, or AMD PDU, the AM RLC layer device may retransmit (considered for retransmission) at least one of the corresponding RLC SDU, SDU Segment, or AMD PDU. For example, the retransmission may be considered as a blind retransmission. For example, the blind retransmission may be performed only when at least one of the corresponding RLC SDU, SDU Segment, or AMD PDU is a delay-critical RLC SDU, SDU Segment, or AMD PDU when the retransmission timer expires or when the retransmission timer starts running. For example, the retransmission may be performed only when the PDCP SDU included in at least one of the corresponding RLC SDU, SDU Segment, or AMD PDU is not a low importance PDU Set. For example, the AM RLC layer device may request a Status PDU by adding a Poll to the AMD PDU performing the retransmission or by setting the P field to 1.

[0374] For example, when performing a blind retransmission for at least one of the specific RLC SDU, SDU Segment, or AMD PDU, a specific blind retransmission counter (e.g., a counter different from RETX_COUNT) or RETX_COUNT corresponding to at least one of the specific RLC SDU, SDU Segment, or AMD PDU may be increased by 1. For example, when performing a blind retransmission for at least one of the specific RLC SDU, SDU Segment, or AMD PDU, RETX_COUNT corresponding to at least one of the specific RLC SDU, SDU Segment, or AMD PDU may not be increased. For example, when performing a blind retransmission for the first time for at least one of the specific RLC SDU, SDU Segment, or AMD PDU, a blind retransmission counter corresponding to at least one of the specific RLC SDU, SDU Segment, or AMD PDU may be initialized to 0. For example, a base station can set a maximum number of blind retransmissions that can be performed for at least one of a specific RLC SDU, SDU Segment, or AMD PDU via an RRC message. For example, blind retransmissions can be performed only when the blind retransmission counter value is less than or equal to the maximum number of blind retransmissions.

[0375] In one embodiment of the present disclosure, at least one of the delay-critical RLC SDUs or SDU Segments in the present disclosure may mean that the remaining time of at least one of the PDCP discardTimer, discardTimerForLowImportance corresponding to at least one of the RLC SDUs or SDU Segments, or a specific Timer run in the RLC layer for at least one of the RLC SDUs or SDU Segments is less than or equal to a specific threshold. For example, the delay-critical AMD PDU may mean an AMD PDU containing at least one of the delay-critical RLC SDUs or SDU Segments. The threshold value may be set by the base station via an RRC message (e.g., an RRCReconfiguration message) so that it can be applied to an RLC / PDCP layer device associated with each RLC / PDCP / MAC / Bearer / LCH / LCG. For example, the threshold value or setting field may be a different threshold value or field from the remainingTimeThreshold used in a Delay Status Report (DSR).

[0376] In an embodiment of the operation of the AM RLC layer device of the present disclosure, the transmitting RLC AM layer device may mean at least one of a terminal RLC layer device or a base station RLC layer device.

[0377] In an embodiment of the operation of the AM RLC layer device of the present disclosure, the receiving RLC AM layer device may mean at least one of a terminal RLC layer device or a base station RLC layer device.

[0378] Figure 7 is a block diagram showing the internal structure of a terminal according to one embodiment of the present invention.

[0379] Referring to FIG. 7, the terminal may include an RF (radio frequency) processing unit (710), a baseband processing unit (720), a storage unit (730), a control unit (740), etc.

[0380] The RF processing unit (710) performs functions for transmitting and receiving signals through a wireless channel, such as signal band conversion and amplification. That is, the RF processing unit (710) up-converts the baseband signal provided from the baseband processing unit (720) into an RF band signal and transmits it through an antenna, and down-converts the RF band signal received through the antenna into a baseband signal. For example, the RF processing unit (710) may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a digital to analog convertor (DAC), an analog to digital convertor (ADC), etc. In FIG. 7, only one antenna is illustrated, but the terminal may be equipped with multiple antennas. In addition, the RF processing unit (710) may include multiple RF chains. Furthermore, the RF processing unit (710) may perform beamforming. For the above beamforming, the RF processing unit (710) can adjust the phase and size of each signal transmitted and received through multiple antennas or antenna elements. In addition, the RF processing unit can perform MIMO and can receive multiple layers when performing the MIMO operation.

[0381] The baseband processing unit (720) performs a conversion function between a baseband signal and a bit stream according to the physical layer specifications of the system. For example, when transmitting data, the baseband processing unit (720) generates complex symbols by encoding and modulating a transmission bit stream. In addition, when receiving data, the baseband processing unit (720) restores the reception bit stream by demodulating and decoding the baseband signal provided from the RF processing unit (710). For example, in the case of following the OFDM (orthogonal frequency division multiplexing) method, when transmitting data, the baseband processing unit (720) generates complex symbols by encoding and modulating a transmission bit stream, maps the complex symbols to subcarriers, and then configures OFDM symbols through an inverse fast Fourier transform (IFFT) operation and a cyclic prefix (CP) insertion. In addition, when receiving data, the baseband processing unit (720) divides the baseband signal provided from the RF processing unit (710) into OFDM symbol units, restores signals mapped to subcarriers through FFT (fast Fourier transform), and then restores the received bit string through demodulation and decoding.

[0382] The baseband processing unit (720) and the RF processing unit (710) transmit and receive signals as described above. Accordingly, the baseband processing unit (720) and the RF processing unit (710) may be referred to as a transmitter, a receiver, a transceiver, or a communication unit. Furthermore, at least one of the baseband processing unit (720) and the RF processing unit (710) may include a plurality of communication modules to support a plurality of different wireless access technologies. In addition, at least one of the baseband processing unit (720) and the RF processing unit (710) may include different communication modules to process signals of different frequency bands. For example, the different wireless access technologies may include a wireless LAN (e.g., IEEE 802.11), a cellular network (e.g., LTE), etc. Additionally, the different frequency bands may include a super high frequency (SHF) (e.g., 2.NRHz, NRhz) band, a millimeter wave (mm wave) (e.g., 60GHz) band.

[0383] The storage unit (730) stores data such as basic programs, application programs, and setting information for the operation of the terminal. In addition, the storage unit (730) provides the stored data at the request of the control unit (740).

[0384] The control unit (740) controls the overall operations of the terminal according to the embodiments of the present invention described above. For example, the control unit (740) transmits and receives signals through the baseband processing unit (720) and the RF processing unit (710). In addition, the control unit (740) records and reads data in the storage unit (740). For this purpose, the control unit (740) may include at least one processor. For example, the control unit (740) may include a communication processor (CP) that performs control for communication and an application processor (AP) that controls upper layers such as application programs.

[0385] Figure 8 is a block diagram showing the configuration of a base station according to one embodiment of the present invention.

[0386] Referring to FIG. 8, the base station may be configured to include an RF processing unit (810), a baseband processing unit (820), a backhaul communication unit (830), a storage unit (840), a control unit (850), etc.

[0387] The RF processing unit (810) performs functions for transmitting and receiving signals through a wireless channel, such as signal band conversion and amplification. That is, the RF processing unit (810) up-converts the baseband signal provided from the baseband processing unit (820) into an RF band signal and transmits it through an antenna, and down-converts the RF band signal received through the antenna into a baseband signal. For example, the RF processing unit (810) may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, etc. Although only one antenna is illustrated in FIG. 8, the base station may be equipped with multiple antennas. In addition, the RF processing unit (810) may include multiple RF chains. Furthermore, the RF processing unit (810) may perform beamforming. For the beamforming, the RF processing unit (810) may adjust the phase and magnitude of each of the signals transmitted and received through multiple antennas or antenna elements. The above RF processing unit can perform a downlink MIMO operation by transmitting one or more layers.

[0388] The baseband processing unit (820) performs a conversion function between a baseband signal and a bit stream according to the physical layer specifications of the first wireless access technology. For example, when transmitting data, the baseband processing unit (820) generates complex symbols by encoding and modulating a transmission bit stream. In addition, when receiving data, the baseband processing unit (820) restores the reception bit stream by demodulating and decoding the baseband signal provided from the RF processing unit (810). For example, in the case of OFDM, when transmitting data, the baseband processing unit (820) generates complex symbols by encoding and modulating a transmission bit stream, maps the complex symbols to subcarriers, and then configures OFDM symbols through IFFT operation and CP insertion. In addition, when receiving data, the baseband processing unit (820) divides the baseband signal provided from the RF processing unit (810) into OFDM symbol units, restores the signals mapped to subcarriers through FFT operation, and then restores the received bit string through demodulation and decoding. The baseband processing unit (820) and the RF processing unit (810) transmit and receive signals as described above. Accordingly, the baseband processing unit (820) and the RF processing unit (810) may be referred to as a transmitter, a receiver, a transceiver, a communication unit, or a wireless communication unit.

[0389] The backhaul communication unit (830) provides an interface for communicating with other nodes within the network. That is, the backhaul communication unit (830) converts a bit string transmitted from the base station to another node, such as another base station (e.g., an auxiliary base station, a main base station, etc.), a core network, etc., into a physical signal, and converts a physical signal received from the other node into a bit string.

[0390] The storage unit (840) stores data such as basic programs, application programs, and configuration information for the operation of the base station. In particular, the storage unit (840) can store information on bearers assigned to connected terminals, measurement results reported from connected terminals, and the like. In addition, the storage unit (840) can store information that serves as a basis for determining whether to provide or terminate multiple connections to a terminal. In addition, the storage unit (840) provides the stored data at the request of the control unit (850).

[0391] The control unit (850) controls the overall operations of the base station according to the embodiments of the present invention described above. For example, the control unit (850) transmits and receives signals through the baseband processing unit (820) and the RF processing unit (810) or through the backhaul communication unit (830). In addition, the control unit (850) records and reads data in the storage unit (840). For this purpose, the control unit (850) may include at least one processor.

[0392] It should be noted that the configuration diagrams, example diagrams of control / data signal transmission methods, example diagrams of operating procedures, and configuration diagrams illustrated in the above FIGS. 1 to 8 are not intended to limit the scope of the present disclosure. That is, not all components, entities, or operational steps described in the above FIGS. 1 to 8 should be construed as essential components for carrying out the disclosure, and the disclosure may be implemented without detriment to its essence even if only some components are included.

[0393] The operations of the network entity or terminal described above can be realized by providing a memory device storing the corresponding program code within any component of the network entity or terminal device. That is, the control unit of the network entity or terminal device can execute the operations described above by reading and executing the program code stored in the memory device using a processor or CPU (Central Processing Unit).

[0394] The various components and modules of the network entity, base station or terminal device described in this specification may be operated using hardware circuits, such as logic circuits based on complementary metal oxide semiconductors, firmware, software and / or hardware and firmware and / or software embedded in a machine-readable medium. For example, various electrical structures and methods may be implemented using electrical circuits such as transistors, logic gates and application-specific semiconductors.

[0395] While the detailed description of this disclosure has described specific embodiments, it should be understood that various modifications are possible without departing from the scope of this disclosure. Therefore, the scope of this disclosure should not be limited to the described embodiments, but should be defined not only by the scope of the claims described below, but also by equivalents thereof.

Claims

1. In a method performed by a terminal in a communication system, A step of transmitting a message to a base station, the message including information on the capabilities of the terminal, the information including information on whether the terminal supports radio link control (RLC) polling related to delay-critical; When the terminal supports RLC Polling related to the delay-critical, a step of receiving a radio resource control (RRC) message including configuration information for RLC Polling related to the delay-critical from the base station; A step of determining a condition for triggering RLC Polling related to the delay-critical based on the RRC message; and A method characterized in that it further comprises the step of transmitting, to the base station, a request message for feedback for retransmission of a protocol data unit (PDU), when the condition for triggering RLC Polling related to the delay-critical is satisfied.

2. In paragraph 1, In response to the request message, receiving a report message including the feedback for retransmission of the PDU from the base station; and A method characterized in that it further comprises the step of performing retransmission for a PDU related to the NACK when the feedback includes a negative acknowledgment (NACK).

3. In paragraph 1, A method further comprising: a step of identifying whether at least one of the protocol data units (PDUs) is a delay-critical PDU based on the RRC message.

4. In paragraph 2, The above RRC message further includes configuration information for RLC Polling, and A method characterized in that the configuration information for the RLC Polling includes at least one of information for calculating the number of protocol data units (PUDs) transmitted after transmitting the request message for requesting the feedback, information for calculating the bytes of the PDUs transmitted after transmitting the request message for requesting the feedback, a timer for retransmitting the request message for requesting the feedback, PDU threshold information for triggering the RLC Polling in relation to the number of the PDUs, and byte threshold information for triggering the RLC Polling in relation to the bytes of the PDUs.

5. In paragraph 2, A method characterized in that the configuration information for RLC Polling related to the delay-critical includes at least one of information for calculating the number of delay-critical protocol data units (PUDs) transmitted after transmitting the request message for requesting the feedback, information for calculating the bytes of the delay-critical PDUs transmitted after transmitting the request message for requesting the feedback, a timer for retransmitting the request message for requesting the feedback in relation to the delay-critical PDUs, PDU threshold information for triggering RLC Polling related to the delay-critical in relation to the number of delay-critical PDUs, and byte threshold information for triggering RLC Polling related to the delay-critical in relation to the bytes of the delay-critical PDUs.

6. In paragraph 5, A method characterized in that a condition for triggering RLC Polling related to the delay-critical is determined based on at least one of the configuration information for RLC Polling related to the delay-critical.

7. In paragraph 5, A method characterized in that it further comprises the step of resetting the timer for retransmitting a request message for requesting the feedback in relation to the delay-critical PDU, when the report message includes information about feedback for retransmission for the delay-critical PDU.

8. In a terminal of a communication system, the terminal: A transceiver configured to transmit and receive signals; and A control unit coupled to the above transmitter and receiver, wherein the control unit: Transmitting a message to a base station containing information about the capabilities of the terminal, the information including information about whether the terminal supports radio link control (RLC) polling related to delay-critical, If the terminal supports RLC Polling related to the delay-critical, it receives a radio resource control (RRC) message including configuration information for RLC Polling related to the delay-critical from the base station, Based on the above RRC message, determine the condition for triggering RLC Polling related to the delay-critical, and A terminal characterized in that, when the above condition for triggering RLC Polling related to the delay-critical is satisfied, a request message for feedback for retransmission of a protocol data unit (PDU) is transmitted to the base station.

9. In paragraph 8, the control unit: In response to the request message, receiving a report message from the base station including the feedback for retransmission of the PDU, and A terminal characterized in that, if the above feedback includes a negative acknowledgment (NACK), retransmission is performed for a PDU related to the NACK.

10. In paragraph 8, the control unit: A terminal characterized in that it identifies whether at least one of the protocol data units (PDUs) is a delay-critical PDU based on the RRC message.

11. In paragraph 10, The above RRC message further includes configuration information for RLC Polling, and A terminal characterized in that the configuration information for the RLC Polling includes at least one of information for calculating the number of protocol data units (PUDs) transmitted after transmitting the request message for requesting the feedback, information for calculating the bytes of the PDUs transmitted after transmitting the request message for requesting the feedback, a timer for retransmitting the request message for requesting the feedback, PDU threshold information for triggering the RLC Polling in relation to the number of PDUs, and byte threshold information for triggering the RLC Polling in relation to the bytes of the PDU.

12. In paragraph 10, A terminal characterized in that the configuration information for RLC Polling related to the delay-critical includes at least one of information for calculating the number of delay-critical protocol data units (PUDs) transmitted after transmitting the request message for requesting the feedback, information for calculating the bytes of the delay-critical PDUs transmitted after transmitting the request message for requesting the feedback, a timer for retransmitting the request message for requesting the feedback in relation to the delay-critical PDUs, PDU threshold information for triggering RLC Polling related to the delay-critical in relation to the number of delay-critical PDUs, and byte threshold information for triggering RLC Polling related to the delay-critical in relation to the bytes of the delay-critical PDUs.

13. In paragraph 12, A terminal characterized in that a condition for triggering RLC Polling related to the delay-critical is determined based on at least one of the configuration information for RLC Polling related to the delay-critical.

14. In paragraph 12, the control unit: A terminal characterized in that, when the above report message includes information about feedback for retransmission for the delay-critical PDU, a timer is reset for retransmitting a request message for requesting the feedback in relation to the delay-critical PDU.

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