Method and apparatus for automatic repeat request based on lower layer information in next generation mobile communication system

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting higher data transmission rates. The disclosure provides a method and an apparatus for supporting data transmission and retransmission in a wireless communication system.

Description

Method and device for automatic repetitive requests based on lower-layer information in a next-generation mobile communication system

[0001] The present disclosure relates to a method and apparatus for supporting data transmission and retransmission in a wireless communication system.

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

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

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

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

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

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

[0008] To improve data transmission efficiency in wireless channel environments, automatic repeat request (ARQ) or hybrid ARQ (HARQ) functions for data transmission may be supported. When supporting both such ARQ and HARQ functions in a single device, it is necessary to consider a method to perform data retransmission operations more efficiently.

[0009] One objective of the present disclosure is to provide a method and apparatus capable of triggering an ARQ retransmission by considering whether the transmission and reception of a HARQ were successful.

[0010] A method of a transmitting device in a wireless communication system according to an example of the present disclosure for solving the above-mentioned problems comprises: a step of transmitting a packet to a receiving device through a first layer that supports a HARQ (hybrid automatic repeat request) function; a step of receiving HARQ information related to the packet transmission from the receiving device; a step of, if a HARQ failure is determined based on the HARQ information, transmitting instruction information indicating the HARQ failure to a second layer that supports an ARQ (automatic repeat request) function from the first layer; and a step of triggering an ARQ retransmission based on the instruction information at the second layer, wherein the second layer is a layer above the first layer, and the instruction information may be transmitted to an ARQ device that provided an ARQ PDU (protocol data unit) included in the packet among at least one ARQ device of the second layer.

[0011] In addition, in a wireless communication system according to one example of the present disclosure, a transmitting device comprises: a transmitting and receiving unit; and a receiving device, wherein the transmitting and receiving unit is controlled to transmit a packet through a first layer that supports a HARQ (hybrid automatic repeat request) function, and the transmitting and receiving unit is controlled to receive HARQ information related to the packet transmission from the receiving device, and when a HARQ failure is determined based on the HARQ information, the first layer is controlled to transmit instruction information indicating the HARQ failure to a second layer that supports an ARQ (automatic repeat request) function, and the second layer is controlled to trigger an ARQ retransmission based on the instruction information, wherein the second layer is a layer above the first layer, and the instruction information may be transmitted to an ARQ device that provided an ARQ PDU (protocol data unit) included in the packet among at least one ARQ device of the second layer.

[0012] According to one embodiment of the present disclosure, since ARQ retransmission is triggered quickly prior to determining whether ARQ transmission and reception were successful, the data retransmission delay can be reduced.

[0013] FIG. 1 is a drawing illustrating the structure of an NR system according to one embodiment of the present disclosure.

[0014] FIG. 2 is a diagram showing a wireless protocol structure in an NR system according to one embodiment of the present disclosure.

[0015] FIG. 3 is a diagram illustrating a procedure for a terminal to establish a connection with a network according to one embodiment of the present disclosure.

[0016] FIG. 4 is a diagram illustrating a lower-layer HARQ failure-based ARQ retransmission method according to one embodiment of the present disclosure.

[0017] FIG. 5 is a block diagram illustrating the internal structure of a terminal according to one embodiment of the present disclosure.

[0018] FIG. 6 is a block diagram showing the configuration of a base station according to one embodiment of the present disclosure.

[0019] The operating principles of the present disclosure will be described in detail below with reference to the attached drawings. In describing the present disclosure below, specific descriptions of related known functions or configurations will be omitted if it is determined that such detailed descriptions would unnecessarily obscure the essence of the present disclosure. Furthermore, the terms described below are defined in consideration of their functions in the present disclosure, and these may vary depending on the intentions or practices of the user or operator. Therefore, their definitions should be based on the content throughout this specification.

[0020] In describing the embodiments of this disclosure, technical details that are well known in the technical field to which this disclosure belongs and are not directly related to this disclosure are omitted. This is intended to convey the essence of this disclosure more clearly without obscuring it by omitting unnecessary explanations.

[0021] For the same reason, some components in the attached drawings have been exaggerated, omitted, or schematically depicted. Additionally, the size of each component does not entirely reflect its actual dimensions. Identical or corresponding components in each drawing have been assigned the same reference numbers.

[0022] The advantages and features of the present disclosure and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below but may be implemented in various different forms. The embodiments provided are merely to make the present disclosure complete and to fully inform those skilled in the art of the scope of the disclosure, and the present disclosure is defined only by the scope of the claims. Throughout the specification, the same reference numerals refer to the same components.

[0023] At this time, it will be understood that each block of the process flow diagrams and combinations of the flow diagrams can be executed by computer program instructions. Since these computer program instructions can be loaded into the processor of a general-purpose computer, a special-purpose computer, or other programmable data processing equipment, the instructions executed through the processor of the computer or other programmable data processing equipment create means to perform the functions described in the flow diagram block(s). Since these computer program instructions can also be stored in computer-available or computer-readable memory that can be directed toward the computer or other programmable data processing equipment to implement the function in a specific way, the instructions stored in computer-available or computer-readable memory can also produce a manufactured item containing the means of instruction to perform the function described in the flow diagram block(s). Since computer program instructions can be loaded onto a computer or other programmable data processing equipment, instructions that perform a series of operation steps on the computer or other programmable data processing equipment to create a process executed by the computer can also provide steps for executing the functions described in the flowchart block(s).

[0024] Additionally, each block may represent a module, segment, or part of code containing one or more executable instructions for executing a specific logical function(s). It should also be noted that in some alternative execution examples, the functions mentioned in the blocks may occur out of order. For instance, two blocks described in succession may actually be executed substantially simultaneously, or the blocks may be executed in reverse order according to their corresponding functions.

[0025] In this embodiment, the term "part" refers to a software or hardware component such as an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit), and the "part" performs certain roles. However, the meaning of "part" is not limited to software or hardware. The "part" may be configured to reside in an addressable storage medium or may be configured to run one or more processors. Accordingly, as an example, the "part" includes components such as software components, object-oriented software components, class components, and task components, as well as processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functions provided within the components and "parts" may be combined into a smaller number of components and "parts" or further separated into additional components and "parts." In addition, the components and '~parts' may be implemented to play one or more CPUs within the device or secure multimedia card.

[0026] Hereinafter, a base station is an entity that performs resource allocation for terminals and may be at least one of a Node B, BS (Base Station), eNB (eNode B), gNB (gNode B), a radio access unit, a base station controller, or a node on a network. A terminal may include a UE (User Equipment), MS (Mobile Station), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing communication functions. Furthermore, the embodiments of the present disclosure may be applied to other communication systems having a technical background or channel type similar to the embodiments of the present disclosure described below. Additionally, the embodiments of the present disclosure may be applied to other communication systems with some modifications made at the discretion of a person with skilled technical knowledge, provided that they do not deviate significantly from the scope of the present disclosure. For example, 5th generation mobile communication technology (5G, new radio, NR) developed after LTE-A may be included therein, and the 5G below may be a concept that includes existing LTE, LTE-A, and other similar services. In addition, the present disclosure may be applied to other communication systems with some modifications made at the discretion of a person with skilled technical knowledge, without significantly departing from the scope of the present disclosure.

[0027] Terms used in the following description to identify connection nodes, terms referring to network entities or network functions (NFs), terms referring to messages, terms referring to interfaces between network entities, terms referring to various identification information, etc., are examples provided for the convenience of explanation. Accordingly, the present disclosure is not limited to the terms described below, and other terms referring to objects having equivalent technical meanings may be used.

[0028] For convenience of explanation below, some terms and names defined in the 3GPP (3rd generation partnership project) LTE (long term evolution) standards and / or 3GPP NR (new radio) standards may be used. However, the present disclosure is not limited by these terms and names and may be equally applied to systems conforming to other standards.

[0029] FIG. 1 is a drawing illustrating the structure of an NR system according to one embodiment of the present disclosure.

[0030] Referring to FIG. 1, a wireless communication system according to one example of the present disclosure may be composed of several base stations (e.g., gNB (100), ng-eNB (110), ng-eNB (120), gNB (130)), an Access and Mobility Management Function (AMF) (140), and a User Plane Function (UPF) (150). Of course, the wireless communication system is not limited to the configuration shown in FIG. 1 and may include more or fewer components.

[0031] According to one embodiment of the present disclosure, a user terminal (User Equipment, hereinafter UE or terminal) (160) can connect to an external network through base stations (100, 110, 120, 130) and a UPF (150).

[0032] In FIG. 1, base stations (100, 110, 120, 130) can provide wireless access to terminals connected to the network as access nodes of a cellular network. For example, base stations (100, 110, 120, 130) can support the connection between terminals and a core network (CN; in particular, the CN of NR (new radio) is referred to as 5GC) by collecting state information such as the buffer state, available transmission power state, and channel state of terminals to service the traffic of users and scheduling.

[0033] In FIG. 1, gNB (100, 130) can control multiple cells, and an Adaptive Modulation & Coding (hereinafter AMC) method can be applied to determine a modulation scheme and a channel coding rate according to the channel state of the terminal (160).

[0034] The core network is a device responsible for various control functions as well as mobility management functions for terminals, and can be connected to multiple base stations. In addition, 5GC can be interoperable with existing LTE systems.

[0035] Meanwhile, in a wireless communication system, a User Plane (UP) related to the transmission of actual user data and a Control Plane (CP) such as connection management can be configured separately. The gNB (100) and gNB (130) of FIG. 1 can use UP and CP technologies defined in NR technology, and the ng-eNB (110) and ng-eNB (120), although connected to 5GC, can use UP and CP technologies defined in LTE (Long Term Evolution) technology.

[0036] The AMF (140) is a device responsible for various control functions as well as mobility management functions for the terminal, and can be connected to multiple base stations.

[0037] UPF (150) may refer to a type of gateway device that provides data transmission. Although not shown in FIG. 1, the NR wireless communication system may include a Session Management Function (SMF). The SMF can manage packet data network connections, such as protocol data unit (PDU) sessions provided to terminals.

[0038] FIG. 2 is a diagram showing a wireless protocol structure in an NR system according to one embodiment of the present disclosure.

[0039] Referring to FIG. 2, the wireless protocol of the NR system can be composed of SDAP (Service Data Adaptation Protocol) (200)(290), PDCP (Packet Data Convergence Protocol) (210)(280), RLC (Radio Link Control) (220)(270), MAC (Medium Access Control) (230)(260), and PHY (Physical) (240)(250) at the terminal and base station, respectively.

[0040] SDAP (Service Data Adaptation Protocol) (200) (290) can transmit user data and perform operations to map QoS (quality of service) flows for uplink and downlink to specific DRBs (data radio bearers), to mark QoS flow IDs (identities) for uplink and downlink, and to map reflective QoS flows for uplink SDAP PDUs (protocol data units) to data bearers. SDAP configurations corresponding to each DRB may be provided by the upper RRC (radio resource control) layer. Of course, this is not limited to the example.

[0041] The PDCP (Packet Data Convergence Protocol) (210) (280) can perform operations such as compressing and decompressing IP (internet protocol) headers. Additionally, the PDCP (210) (280) can provide sequential and non-sequential delivery functions, reorder the data, detect duplicates, retransmit data, and provide encryption and decryption functions. Of course, it is not limited to these examples.

[0042] Radio Link Control (220)(270) can reconfigure the PDCP Protocol Data Unit (PDU) to an appropriate size. Additionally, RLC (220)(270) provides sequential and non-sequential delivery functions and can provide ARQ functions, splicing, splitting, reassembling, resegmentation, reordering, duplicate detection, and error detection functions. Of course, it is not limited to these examples.

[0043] The MAC (230)(260) is connected to multiple RLC layer devices configured in a terminal and can perform operations to multiplex RLC PDUs into MAC PDUs and demultiplex RLC PDUs from MAC PDUs. Additionally, the MAC (230)(260) can provide mapping functions, scheduling information reporting functions, HARQ (hybrid automatic repeat request) functions, priority control functions between logical channels, priority control functions between terminals, MBMS (multimedia broadcast multicast service) service verification functions, transmission format selection functions, and padding functions. Of course, it is not limited to these examples.

[0044] The physical (PHY) layer (240)(250) performs the operation of channel coding and modulating upper layer data, creating OFDM (orthogonal frequency division multiplexing) symbols to transmit to the wireless channel, or demodulating OFDM symbols received through the wireless channel and channel decoding to transmit to the upper layer. In addition, the physical layer also uses HARQ (Hybrid ARQ) for additional error correction, and the receiving end transmits a 1-bit information indicating whether the packet transmitted by the transmitting end has been received. The 1-bit information is called HARQ ACK (acknowledgement) / NACK (Negative ACK) information.

[0045] In the case of LTE, downlink HARQ ACK / NACK information for uplink data transmission is transmitted via the physical channel of PHICH (Physical Hybrid-ARQ Indicator Channel), whereas in the case of NR, ACK / NACK can be determined by indicating whether retransmission is required or if a new transmission should be performed through the terminal's scheduling information in the PDCCH (Physical Dedicated Control Channel), which is the channel where downlink / uplink resource allocation is transmitted. This is because asynchronous HARQ is applied in NR. Uplink HARQ ACK / NACK information for downlink data transmission can be transmitted via the physical channels of PUCCH (Physical Uplink Control Channel) or PUSCH (Physical Uplink Shared Channel). PUCCH is generally transmitted on the uplink of the PCell (primary cell) described later, but if the terminal supports it, the base station may additionally transmit it to the SCell (secondary cell) described later for that terminal, and this is referred to as PUCCH SCell.

[0046] Although not shown in Fig. 2, a Radio Resource Control (RRC) layer exists above the PDCP layer of the terminal and the base station, respectively, and the RRC layer can transmit and receive connection and measurement-related setting control messages for wireless resource control.

[0047] Meanwhile, the physical layer can consist of one or more frequencies / carriers, and the technology of setting and using multiple frequencies simultaneously is called carrier aggregation (hereinafter referred to as CA). CA refers to a technology that allows for a significant increase in transmission capacity by the number of secondary carriers by using a main carrier and one or more secondary carriers in addition to the main carrier, whereas previously only one carrier was used for communication between a terminal (or User Equipment, UE) and a base station (eNB or gNB). Meanwhile, in LTE / NR, a cell within a base station that uses a main carrier is called a main cell or PCell, and a cell within a base station that uses a secondary carrier is called a secondary cell or SCell.

[0048] FIG. 3 is a diagram illustrating a procedure for a terminal to establish a connection with a network according to one embodiment of the present disclosure.

[0049] FIG. 3 illustrates the procedure in which a terminal in the present disclosure switches from RRC idle mode (RRC_IDLE) to RRC connected mode (RRC_CONNECTED) to establish a connection with a network.

[0050] Referring to FIG. 3, the terminal establishes up / down link transmission synchronization with the base station through a random access process and transmits an RRCSetupRequest message to the base station (300). The RRCSetupRequest message may contain the terminal's identifier and the reason for establishing the connection (EstablishmentCause).

[0051] The base station sends an RRCSetup message to the terminal to establish an RRC connection (305).

[0052] In one embodiment, the RRCSetup message may include configuration information (RadioBearerConfig) for each Radio Bearer (DRB or SRB (signaling radio bearer)). The Radio Bearer configuration information may include the ID (identify) of each Radio Bearer, configuration information (PDCP-Config) for the PDCP layer device of the Radio Bearer, and an indicator indicating whether the Radio Bearer is a DAPS (Dual Active Protocol Stack) Bearer.

[0053] Additionally, in one embodiment, the RRCSetup message may include configuration information (e.g., CellGroupConfig) for each Cell Group (Master Cell Group and / or Secondary Cell Group). The Cell Group configuration information (CellGroupConfig) may include configuration information (e.g., RLC-BearerConfig) for each RLC bearer to be configured for one or more RLC bearers in the corresponding Cell Group.

[0054] In one embodiment, the RLC-BearerConfig configuration information may include the following fields. The description for each field may be as follows.

[0055] - logicalChannelIdentity: ID used commonly for the MAC logical channel and for the RLC bearer. Value 4 is not configured for DRBs if SRB4 is configured.

[0056] - servedRadioBearer: Associates the RLC Bearer with an SRB or a DRB. The UE shall deliver DL RLC SDUs received via the RLC entity of this RLC bearer to the PDCP entity of the servedRadioBearer. Furthermore, the UE shall advertise and deliver uplink PDCP PDUs of the uplink PDCP entity of the servedRadioBearer to the uplink RLC entity of this RLC bearer unless the uplink scheduling restrictions (moreThanOneRLC in PDCP-Config and the restrictions in LogicalChannelConfig) forbid it to do so.

[0057] - reestablishRLC: Indicates that RLC should be re-established. Network sets this to true at least whenever the security key used for the radio bearer associated with this RLC entity changes. For SRB2, multicast MRBs and DRBs, unless full configuration is used, it is also set to true during the resumption of the RRC connection or the first reconfiguration after reestablishment. For SRB1, when resuming an RRC connection, or at the first reconfiguration after RRC connection reestablishment, the network does not set this field to true. The network does not include this field if the RLC-BearerConfig IE is part of an RRCReconfiguration message within the LTM-Config IE.

[0058] - rlc-Config: Determines the RLC mode (UM, AM) and provides corresponding parameters. RLC mode reconfiguration can only be performed by DRB / multicast MRB release / addition or full configuration. The network may configure rlc-Config-v1610 only when rlc-Config (without suffix) is set to am.

[0059] - mac-LogicalChannelConfig: May contain Logical Channel configuration information for the corresponding RLC bearer.

[0060] In one embodiment, the rlc-Config may include RLC layer device configuration information of an RLC bearer. For example, the rlc-Config may include the following fields. A description of each field may be as follows.

[0061] - When the RLC layer device is set to AM (acknowledged mode):

[0062] ■ ul-AM-RLC configuration information: sn-FieldLength(Sequence Number length), t-PollRetransmit(Poll retransmission timer size), pollPDU(Poll trigger PDU count threshold), pollByte(Poll trigger Byte threshold), maxRetxThreshold(maximum retransmission count).

[0063] ■ dl-AM-RLC configuration information: sn-FieldLength(Sequence Number length), t-Reassembly(Reassembly timer size), t-StatusProhibit(Status PDU prohibition timer size).

[0064] - When the RLC layer device is set to UM (unacknowledged mode) Bi-Directional mode:

[0065] ■ ul-UM-RLC configuration information: sn-FieldLength(Sequence Number length)

[0066] ■ dl-UM-RLC Configuration Information: sn-FieldLength (Sequence Number Length), t-Reassembly (Reassembly Timer Size)

[0067] - When the rlc hierarchy device is set to UM Uni-Directional-UL mode:

[0068] ■ ul-UM-RLC configuration information: sn-FieldLength(Sequence Number length)

[0069] - When the rlc hierarchy device is set to UM Uni-Directional-DL mode:

[0070] ■ dl-UM-RLC Configuration Information: sn-FieldLength (Sequence Number Length), t-Reassembly (Reassembly Timer Size)

[0071] Referring to FIG. 3, the terminal that has established the RRC connection enters RRC_CONNECTED mode and sends an RRCSetupComplete message to the base station (310).

[0072] If the base station does not know the terminal capability of the terminal currently establishing a connection, or wants to determine the terminal capability, the base station may send a message asking about the terminal's capability (e.g., UECapabilityEnquiry) to the terminal (315). Then the terminal may send a message reporting the terminal's capability (e.g., UECapabilityInformation) to the base station (320).

[0073] The base station sends a SecurityModeCommand message (325) to the terminal to establish security with the terminal, and the terminal sends a SecurityModeComplete message (330) to the base station.

[0074] Once the security settings are complete, the base station sends an RRCReconfiguration message to the terminal (335).

[0075] In one embodiment, the RRCReconfiguration message may include configuration information (RadioBearerConfig) for each Radio Bearer (DRB or SRB). The Radio Bearer configuration information may include the ID of each Radio Bearer, configuration information (PDCP-Config) for the PDCP layer device of the Radio Bearer, and an indicator indicating whether the Radio Bearer is a DAPS Bearer.

[0076] In one embodiment, the RRCReconfiguration message may include configuration information (e.g., CellGroupConfig) for each Cell Group (Master Cell Group and / or Secondary Cell Group). The Cell Group configuration information (CellGroupConfig) may include configuration information (e.g., RLC-BearerConfig) for each RLC bearer to be configured for one or more RLC bearers in the corresponding Cell Group.

[0077] In one embodiment, the RLC-BearerConfig configuration information may include the following fields. The description for each field may be as follows.

[0078] - logicalChannelIdentity: ID used commonly for the MAC logical channel and for the RLC bearer. Value 4 is not configured for DRBs if SRB4 is configured.

[0079] - servedRadioBearer: Associates the RLC Bearer with an SRB or a DRB. The UE shall deliver DL RLC SDUs received via the RLC entity of this RLC bearer to the PDCP entity of the servedRadioBearer. Furthermore, the UE shall advertise and deliver uplink PDCP PDUs of the uplink PDCP entity of the servedRadioBearer to the uplink RLC entity of this RLC bearer unless the uplink scheduling restrictions (moreThanOneRLC in PDCP-Config and the restrictions in LogicalChannelConfig) forbid it to do so.

[0080] - reestablishRLC: Indicates that RLC should be re-established. Network sets this to true at least whenever the security key used for the radio bearer associated with this RLC entity changes. For SRB2, multicast MRBs and DRBs, unless full configuration is used, it is also set to true during the resumption of the RRC connection or the first reconfiguration after reestablishment. For SRB1, when resuming an RRC connection, or at the first reconfiguration after RRC connection reestablishment, the network does not set this field to true. The network does not include this field if the RLC-BearerConfig IE is part of an RRCReconfiguration message within the LTM-Config IE.

[0081] - rlc-Config: Determines the RLC mode (UM, AM) and provides corresponding parameters. RLC mode reconfiguration can only be performed by DRB / multicast MRB release / addition or full configuration. The network may configure rlc-Config-v1610 only when rlc-Config (without suffix) is set to am.

[0082] - mac-LogicalChannelConfig: May contain Logical Channel configuration information for the corresponding RLC bearer.

[0083] In one embodiment, the rlc-Config may include RLC layer device configuration information of an RLC bearer. For example, the rlc-Config may include the following fields. A description of each field may be as follows.

[0084] - When the RLC layer device is set to AM (acknowledged mode):

[0085] ■ ul-AM-RLC configuration information: sn-FieldLength(Sequence Number length), t-PollRetransmit(Poll retransmission timer size), pollPDU(Poll trigger PDU count threshold), pollByte(Poll trigger Byte threshold), maxRetxThreshold(maximum retransmission count).

[0086] ■ dl-AM-RLC configuration information: sn-FieldLength(Sequence Number length), t-Reassembly(Reassembly timer size), t-StatusProhibit(Status PDU prohibition timer size).

[0087] - When the RLC layer device is set to UM (unacknowledged mode) Bi-Directional mode:

[0088] ■ ul-UM-RLC configuration information: sn-FieldLength(Sequence Number length)

[0089] ■ dl-UM-RLC Configuration Information: sn-FieldLength (Sequence Number Length), t-Reassembly (Reassembly Timer Size)

[0090] - When the rlc hierarchy device is set to UM Uni-Directional-UL mode:

[0091] ■ ul-UM-RLC configuration information: sn-FieldLength(Sequence Number length)

[0092] - When the rlc hierarchy device is set to UM Uni-Directional-DL mode:

[0093] ■ dl-UM-RLC Configuration Information: sn-FieldLength (Sequence Number Length), t-Reassembly (Reassembly Timer Size)

[0094] As such, the general connection setup process consists of three stages: RRC connection setup, security setup, and DRB setup. Additionally, the base station may send an RRCReconfiguration message to the terminal to provide the terminal with a new setup for a specific reason, or to add or change the setup for the terminal (350).

[0095] In one embodiment of the present disclosure, a terminal that receives an RRC message (RRCReconfiguration) may configure each Radio Bearer by the Radio Bearer configuration of the message, configure the corresponding PDCP layer device, configure an RLC Bearer / layer device having an association relationship with each Radio Bearer / PDCP layer device, and then establish an association relationship between the RLC layer device and the PDCP layer device. In one embodiment, one Radio Bearer corresponds to one PDCP layer device. In one embodiment, each PDCP layer device may be associated with one, two, three, four, six, or eight RLC layer devices as follows.

[0096] - The PDCP layer device of the Split Bearer may be associated with two uplink or two downlink UM RLC layer devices, four UM RLC layer devices (two downlink and two uplink), or two AM RLC layer devices.

[0097] - A radio bearer (RB) with PDCP redundancy transmission enabled may be associated with N UM RLC layer devices (all downlink or all uplink), 2 x N UM RLC layer devices (N uplink and N downlink), or N AM RLC layer devices. Here, N may be greater than or equal to 2 and less than or equal to 4.

[0098] - The PDCP layer device of the DAPS Bearer may be associated with two UM RLC layer devices (all uplink or all downlink, one source cell and the other target cell), four UM RLC layer devices (uplink and downlink of the source cell, uplink and downlink of the target cell), or two AM RLC layer devices (one source cell and the other target cell).

[0099] - In other cases, each PDCP layer device may be associated with one UM RLC layer device, two UM RLC layer devices (one uplink and one downlink), or one AM RLC layer device.

[0100] In one embodiment of the present disclosure, an RLC hierarchical device may operate in one of Transparent Mode (TM), Unacknowledged Mode (UM), or Acknowledged Mode (AM). Accordingly, the RLC hierarchical device may be referred to as a TM RLC hierarchical device, a UM RLC hierarchical device, or an AM RLC hierarchical device depending on the mode.

[0101] For example, the UM RLC layer device can operate as either a transmitting UM RLC layer device (Transmitting UM RLC Entity) or a receiving UM RLC layer device (Receiving UL RLC Entity).

[0102] For example, an AM RLC layer device can be composed of a transmitting side and a receiving side.

[0103] In one embodiment of the present disclosure, each RLC service data unit (SDU) may be made into an RLC PDU without a transmission opportunity notification from a lower layer (e.g., MAC). A UM RLC layer device or an AM RLC layer device may divide a single RLC SDU into two or more segments based on a transmission opportunity notification from a lower layer and transmit it as two or more RLC PDUs. For example, an RLC layer device may submit an RLC PDU to a lower layer after receiving a transmission opportunity notification from a lower layer (e.g., MAC, PHY layer).

[0104] The present disclosure proposes a method for triggering ARQ retransmission by considering the success or failure of HARQ transmission and reception in a device in which a layer providing ARQ functionality (e.g., an RLC layer) and a layer providing HARQ functionality (e.g., a MAC / PHY layer) coexist. By applying the method proposed in the present disclosure, faster ARQ retransmission may be possible based on the success or failure of HARQ transmission and reception before the success or failure of ARQ transmission and reception is known.

[0105] The method proposed in this disclosure can be applied not only to 4G, 5G, and 5G-Advance but also to future next-generation 6G communication systems. Hereinafter, in this disclosure, a layer providing ARQ functions may be referred to as the ARQ layer. For example, an ARQ layer device may be an RLC layer device operating in RLC AM mode. For example, an ARQ layer device may be an existing layer device or a new layer device providing ARQ functions.

[0106] For the sake of understanding, the operation of the ARQ layer device in this disclosure is described on the premise that the ARQ layer device is an RLC AM layer device. However, this is merely an example, and it is obvious that the ARQ layer device providing the ARQ function can be an existing layer device or a new layer device.

[0107] In this disclosure, based on a layer device providing an ARQ function, a layer device (lower layer device) located lower than said layer device may be referred to as a layer device providing a HARQ function. For example, the lower layer device in this disclosure may be a MAC layer device or a PHY layer device. For the sake of understanding, this disclosure describes the operation of said layer device providing a HARQ function on the premise that said layer device providing a HARQ function is a MAC layer device. However, this is merely an example and this disclosure is not limited thereto, and it is obvious that the device providing a HARQ function may include existing devices or new layer devices.

[0108] For example, in this disclosure, the ARQ layer may refer to a layer that provides ARQ functions other than the RLC layer. Additionally, the operation / configuration described for the RLC layer in this disclosure may be considered as one embodiment of the operation / configuration of the ARQ layer. The operation / configuration method described for the ARQ layer in this disclosure may also be applied to the RLC layer.

[0109] For example, in the present disclosure, the lower layer may refer to the MAC layer. Also, for example, in the present disclosure, the lower layer may refer to the PHY layer.

[0110] Additionally, as an example, in the present disclosure, the upper layer may refer to the PDCP layer. In the present disclosure, the upper layer may refer to the RRC layer.

[0111] Additionally, as an example, in the present disclosure, the RLC AM / ARQ transmitting side may refer to the transmitting side of an AM RLC / ARQ layer device. In the present disclosure, the RLC AM / ARQ receiving side may refer to the receiving side of an AM RLC / ARQ layer device.

[0112] Additionally, as an example, the retransmission operation performed by the RLC AM transmitting side in the present disclosure can be considered as one embodiment of the ARQ retransmission operation.

[0113] FIG. 4 is a diagram illustrating a lower-layer HARQ failure-based ARQ retransmission method according to one embodiment of the present disclosure.

[0114] Referring to FIG. 4, the ARQ transmitting device may include one or more ARQ layer (400) devices and at least one lower layer (405) device. The ARQ receiving device may include one or more ARQ layer (415) devices and at least one lower layer (410) device.

[0115] In one embodiment of the present disclosure, an ARQ transmitting device (e.g., a terminal) may be allocated a transmission resource (e.g., Dynamic Uplink Grant, Configured Uplink Grant) from an ARQ receiving device (e.g., a base station) (420). The ARQ transmitting device may configure a lower layer PDU (e.g., MAC PDU, Transport Block) to be transmitted through the allocated transmission resource. The lower layer PDU may include one or more ARQ PDUs (e.g., at least one of an RLC PDU, RLC SDU, RLC PDU Segment, RLC SDU Segment) for each layer device of one or more ARQ layer devices containing data to be transmitted.

[0116] The lower layer device (405) may determine how much ARQ PDU to include in the lower layer PDU for each ARQ layer device by undergoing a predetermined resource allocation procedure (e.g., Logical Channel Prioritization) to configure the lower layer PDU to be transmitted through the allocated transmission resource. For example, the lower layer device (405) may determine the size of the transmission resource allocated to each ARQ layer device and the total size of the ARQ PDU(s) among the allocated transmission resource and the lower layer PDU to be configured. The lower layer device (405) may transmit an internal control signal 1 containing at least one of the resource information allocated to the ARQ layer device (e.g., size of the allocated transmission resource) or the ID / SN (Sequence Number) of the lower layer PDU for each ARQ layer device to which the transmission resource is allocated (425).

[0117] An ARQ layer device (400) that receives an internal control signal 1 can configure one or more ARQ PDUs to be included in a lower layer PDU based on transmission resource information and / or lower layer PDU ID / SN assigned to the ARQ layer device (400) included in the internal control signal 1. After configuring the ARQ PDUs, the ARQ layer device (400) can perform operation 1 (430). For example, operation 1 may include at least one of the following operations.

[0118] - If at least one ARQ PDU is included in a lower-level PDU, the ID / SN of the lower-level PDU and the ID / SN of one or more ARQ PDUs of the corresponding ARQ layer device to be included in the lower-level PDU can be stored in a predetermined data structure / variable. For example, if the lower-level PDU SN is j, and there are two ARQ PDUs of the corresponding ARQ layer device to be included in the lower-level PDU corresponding to j, and the SNs for the two ARQ PDUs are a1 and a2 respectively, the ARQ layer device (400) can configure and store the following table.

[0119]

[0120] For example, if a specific ARQ PDU to be included in a lower-level PDU corresponds to a segment of a specific SDU (e.g., RLC SDU), an indicator indicating which byte of the SDU the first byte of the said SDU segment corresponds to can be stored together in the table. For example, if a specific ARQ PDU to be included in a lower-level PDU corresponds to a segment of a specific SDU (e.g., RLC SDU), an indicator indicating which byte of the SDU the last byte of the said SDU segment corresponds to can be stored together in the table. For example, if a specific ARQ PDU to be included in a lower-level PDU corresponds to a segment of a specific SDU (e.g., RLC SDU), an indicator indicating the length of the said SDU segment can be stored together in the table.

[0121] In one embodiment of the present disclosure, a specific ARQ layer device (400) may transmit one or more ARQ PDUs and / or internal control signals 2 to the lower layer to be included in the lower layer PDU (435).

[0122] In one embodiment of the present disclosure, the internal control signal 2 may include at least one of the following information.

[0123] - Information on the ID / SN of one or more ARQ PDUs to be included in the lower-level PDU

[0124] - Information regarding an indicator that indicates which byte of the SDU the first byte of the said SDU segment corresponds to, when a lower-level PDU contains a segment of a specific SDU (e.g., RLC SDU).

[0125] - Information regarding an indicator that specifies which byte of the SDU the last byte of the said SDU segment is, when the lower-level PDU contains a segment of a specific SDU (e.g., RLC SDU).

[0126] - Information regarding the indicator that indicates the length of the said SDU segment when the lower-level PDU contains a segment of a specific SDU (e.g., RLC SDU).

[0127] In one embodiment of the present disclosure, a lower layer device (405) that receives a control signal 2 can perform operation 2 (440). For example, operation 2 may include at least one of the following operations.

[0128] - The lower-level PDU ID / SN and the identifiers (e.g., RLC channel ID, logical channel ID, RLC entity ID) of each ARQ layer device containing the corresponding data / ARQ PDU can be stored together. For example, if the lower-level PDU ID is j, and the PDU contains data / ARQ PDUs from two ARQ layer devices, and the IDs of the two ARQ layer devices are L1 and L2, respectively, the lower-level device can store relevant information for the PDU with ID j in the form of the following table.

[0129]

[0130] - The ID / SN of the lower-level PDU, the identifiers of each ARQ layer device containing data / ARQ PDUs for that lower-level PDU (e.g., RLC channel ID, logical channel ID, RLC entity ID), and the ARQ PDU ID / SN of each ARQ layer device included in that lower-level PDU can be stored together. For example, if the ID of the lower-level PDU is j, and the PDU contains data / ARQ PDUs of two ARQ layer devices, and the IDs of the two ARQ layer devices are L1 and L2 respectively, and the ID / SNs of the corresponding ARQ PDUs of the first ARQ layer device are a11 and a12, and the ID / SNs of the corresponding ARQ PDUs of the second ARQ layer device are a21 and a22, the lower-level device can store relevant information for the PDU of ID j in the form of the following table.

[0131]

[0132] - If a lower-level PDU contains a segment of a specific SDU (e.g., RLC SDU), an indicator indicating which byte of the SDU the first byte of the SDU segment is can be stored together with the corresponding ARQ PDU SN.

[0133] - If a lower-level PDU contains a segment of a specific SDU (e.g., RLC SDU), an indicator indicating which byte of the SDU the last byte of the SDU segment is can be stored together with the corresponding ARQ PDU SN.

[0134] - If a lower-level PDU contains a segment of a specific SDU (e.g., RLC SDU), an indicator indicating the length of the SDU segment can be stored together with the corresponding ARQ PDU SN.

[0135] In one embodiment of the present disclosure, an ARQ transmitting device may transmit a lower layer PDU to an ARQ receiving device. The transmission may be performed via HARQ transmission.

[0136] The ARQ receiving device may provide HARQ Feedback to the ARQ transmitting device for a specific lower layer PDU transmission (455). If the ARQ receiving device sends a HARQ transmission failure instruction for a specific lower layer PDU (e.g., instruction via HARQ Feedback), or if the ARQ receiving device requests a HARQ retransmission for a specific lower layer PDU (e.g., instruction via DCI), the ARQ transmitting device may trigger (460) and perform a HARQ retransmission for the corresponding lower layer PDU (465).

[0137] In one embodiment of the present disclosure, an ARQ transmitting device can determine a HARQ failure based on operation 3 for a specific lower layer PDU (480). For example, operation 3 may include at least one of the following operations.

[0138] - If HARQ transmission / reception failures occur more than a certain number of times as configured by the base station (e.g., settings configured by the base station via RRC messages for each RLC layer device / MAC layer device / PHY layer device / terminal / lower layer device / ARQ layer device / HARQ Entity / HARQ Process) (e.g., HARQ feedback provided by the ARQ receiving device indicates a HARQ transmission / reception failure, or a retransmission request for the corresponding lower layer PDU indicated by the ARQ receiving device), it can be determined that there is a HARQ failure for the corresponding lower layer PDU.

[0139] - If the channel status provided by the ARQ receiving device (e.g., RSRP (reference signal received power), RSRQ (reference signal received quality), SNR (signal to noise ratio)) is below a specific threshold value set by the base station (e.g., a setting by the base station via RRC message for each RLC layer device, MAC layer device, PHY layer device, terminal, lower layer device, ARQ layer device, HARQ Entity, or HARQ Process), it can be determined that the HARQ for the corresponding lower layer PDU has failed.

[0140] - If the ARQ receiving device indicates a HARQ failure for the corresponding lower-layer PDU, the ARQ transmitting device may determine that the corresponding lower-layer PDU is a HARQ failure. For example, the HARQ failure indication may be indicated for the corresponding lower-layer PDU via lower-layer control signals (e.g., DCI (downlink control information), UCI (uplink control information), MAC CE (control element)).

[0141] - If the lower layer (e.g., MAC, PHY) of the ARQ transmitting device fails to completely transmit the corresponding lower layer PDU (e.g., transmission of the corresponding lower layer PDU (CG / DG transmission) is deprioritized due to transmission of a higher priority SR (scheduling request) / CG (configured grant) / DG (dynamic grant) that overlaps with time resources), the lower layer device may determine that the lower layer PDU is a HARQ failure.

[0142] In one embodiment of the present disclosure, when a HARQ failure occurs for a specific lower-layer PDU, the lower-layer device may, for each ARQ layer device associated with the lower-layer PDU (where data exists in the PDU), direct an ARQ retransmission and / or HARQ failure for the ARQ PDU included in the lower-layer PDU among the ARQ PDUs of the ARQ layer device. For example, when a HARQ failure occurs for a specific lower-layer PDU, the lower-layer device may, for each ARQ layer device associated with the lower-layer PDU, direct the HARQ failure of the lower-layer PDU.

[0143] In one embodiment of the present disclosure, when a HARQ failure occurs for a specific lower-level PDU, the lower-level device may transmit the corresponding internal control signal 3 to each ARQ level device associated with the PDU (where data exists in the PDU) (485). For example, the internal control signal 3 may include at least one of the following information.

[0144] - Information regarding HARQ failure indications and / or the ID / SN of the lower-level PDU determined to be a HARQ failure

[0145] - Information regarding the ID / SN List of the ARQ PDU of the corresponding ARQ layer device included in the lower layer PDU determined to be a HARQ failure. If the lower layer PDU includes a segment of a specific SDU (e.g., RLC SDU), the internal control signal 3 may include information regarding an indicator indicating which byte of the SDU the first byte of the SDU segment is, and information regarding the corresponding ARQ PDU SN. If the lower layer PDU includes a segment of a specific SDU (e.g., RLC SDU), the internal control signal 3 may include information regarding an indicator indicating which byte of the SDU the last byte of the SDU segment is, and information regarding the corresponding ARQ PDU SN. If a lower-level PDU contains a segment of a specific SDU (e.g., RLC SDU), information regarding an indicator indicating the length of the SDU segment may be included in the internal control signal 3, along with information regarding the corresponding ARQ PDU SN.

[0146] In one embodiment of the present disclosure, an ARQ layer device that receives an internal control signal 3 can perform operation 4 (490). For example, operation 4 may include at least one of the following operations.

[0147] - If an ARQ retransmission instruction / HARQ failure instruction for a specific ARQ PDU of the ARQ layer device is received from a lower layer device via internal control signal 3, the ARQ layer device may trigger ARQ retransmission for the ARQ PDU.

[0148] - When a HARQ failure instruction for a specific lower-layer PDU or a retransmission instruction for an ARQ PDU included in a specific lower-layer PDU is received from a lower-layer device via internal control signal 3, ARQ retransmission can be triggered for the ARQ PDU of the corresponding ARQ layer device included in the corresponding lower-layer PDU. The ARQ layer device can trigger ARQ retransmission for the corresponding ARQ PDU based on ARQ PDU information included in the corresponding lower-layer PDU stored in a predetermined variable or table. For example, an ARQ retransmission trigger for a specific ARQ PDU can be triggered only if ARQ retransmission for that ARQ PDU has not yet been triggered. For example, an ARQ retransmission trigger for a specific ARQ PDU can be triggered only if that ARQ PDU does not yet exist in the ARQ retransmission buffer of the corresponding ARQ layer device.

[0149] In one embodiment of the present disclosure, an ARQ transmitting device may receive a HARQ failure instruction for a specific lower layer PDU from a lower layer. For example, the ARQ transmitting device may trigger an ARQ retransmission for an ARQ PDU included in the lower layer PDU that received the HARQ failure instruction. This can reduce the retransmission trigger delay compared to existing ARQ retransmission methods.

[0150] In one embodiment of the present disclosure, an ARQ transmitting device may trigger an ARQ retransmission for a specific ARQ PDU when it receives an ARQ NACK from an ARQ receiving device. For example, the ARQ layer may be an RLC layer, and the ARQ NACK may be received via an RLC Status Report / PDU.

[0151] In one embodiment of the present disclosure, when an ARQ layer device performs retransmission for a specific ARQ PDU, it may perform at least one of the following operations. This may include at least one of an ARQ retransmission triggered by the aforementioned HARQ failure and an ARQ retransmission triggered by the reception of an ARQ NACK.

[0152] - If an ARQ retransmission is performed for the first time for the ARQ PDU, the retransmission counter (e.g., RETX_COUNT) of the ARQ PDU may be set to 0. For example, a dedicated ARQ retransmission counter (e.g., RETX_COUNT_HARQ) may be introduced for each ARQ PDU for an ARQ retransmission triggered by a HARQ failure, and if an ARQ retransmission triggered by a HARQ failure is performed for the first time for the ARQ PDU, the RETX_COUNT_HARQ of the ARQ PDU may be set to 0.

[0153] - Otherwise, and if the ARQ PDU to be retransmitted is not yet in a pending state for ARQ retransmission, and the RETX_COUNT of that ARQ PDU has not yet been incremented by another Negative Acknowledgement of the same STATUS PDU, and / or by a HARQ failure instruction of the same lower-level PDU:

[0154] - The RETX_COUNT of the ARQ PDU may be increased by 1. For example, if the ARQ retransmission of the ARQ PDU is an ARQ retransmission triggered by a HARQ failure, the RETX_COUNT_HARQ of the ARQ PDU may be increased by 1. For example, the RETX_COUNT of the ARQ PDU may not be increased or decreased for an ARQ retransmission triggered by a HARQ failure of the lower layer PDU. For example, the RETX_COUNT of the ARQ PDU may be increased by 1 for an ARQ retransmission triggered by a HARQ failure of the lower layer PDU. For example, if ARQ feedback (e.g., ARQ Status Report) is disabled for the ARQ layer device, the RETX_COUNT may be increased by 1 for an ARQ retransmission triggered by a HARQ failure of the lower layer PDU.

[0155] - If RETX_COUNT is equal to a specific threshold value set by the base station (e.g., maxRetxThreshold):

[0156] - It can notify the upper layer (e.g., RRC layer) that the maximum retransmission has been reached.

[0157] - For example, if RETX_COUNT_HARQ is equal to a specific threshold value set by the base station (e.g., maxRetxThreshold or a dedicated threshold for RETX_COUNT_HARQ, maxRetxHARQ-Threshold):

[0158] - It can notify the upper layer (e.g., RRC layer) that the maximum retransmission has been reached.

[0159] In one embodiment of the present disclosure, as described in step 315 of FIG. 3, a base station may transmit a UECapabilityEnquiry message requesting a capability report to a terminal in an RRC connection state. At this time, the base station may include a terminal capability request by RAT type in the UECapabilityEnquiry message. For example, when the base station requests the terminal to generate a UECapabilityInformation message through the capability request message, it may include filtering information that can indicate conditions and limitations. For example, the filtering information may include frequency band list information requesting a capability report by RAT type. For example, the filtering information may indicate whether the terminal by RAT type needs to report whether it supports a specific function. For example, the filtering information may indicate whether the terminal needs to report whether it supports the ARQ retransmission function via lower-layer HARQ failure proposed in the present disclosure, for each specific RAT type (e.g., NR). In response to the base station's UECapabilityEnquiry message, the terminal can compose a UECapabilityInformation message and report it to the base station.

[0160] A terminal according to one example of the present disclosure may include a field in the UECapabilityInformation message indicating whether the terminal supports the lower-layer HARQ failure-based ARQ retransmission function proposed in the present disclosure. For example, the field may be represented as 1-bit information (e.g., 1: supported, 0: not supported). As another example, if the field is included in the UECapabilityInformation message, it may indicate that the function is supported, and if the field is not included, it may indicate that the function is not supported.

[0161] A base station can determine whether the terminal supports the lower-layer HARQ failure-based ARQ retransmission function proposed in this disclosure through the UECapabilityInformation message transmitted by the terminal. For example, if the base station determines that the terminal supports the lower-layer HARQ failure-based ARQ retransmission function proposed in this disclosure, it can transmit configuration information related to the lower-layer HARQ failure-based ARQ retransmission function to the terminal through an RRCReconfiguration message such as step 335 of FIG. 3, in the configuration information per ARQ (e.g., RLC) layer device / logical channel / bearer. For example, the lower-layer HARQ failure-based ARQ retransmission configuration information included in the RRCReconfiguration message may include at least one of the following information.

[0162] - Configuration information for setting whether to enable or activate the lower layer HARQ failure-based ARQ retransmission function in the ARQ layer device. The configuration information may be represented as 1-bit information (e.g., 1-enable, 0-disable). For example, if the configuration information includes a specific field, it indicates that the function is enabled, and if the field is not included, it indicates that the function is not enabled.

[0163] - Information for setting the remaining time threshold of an ARQ PDU to enable / apply the lower-layer HARQ failure-based ARQ retransmission function in the corresponding ARQ layer device. The setting for the threshold may be provided per RLC layer device / bearer / logical channel / logical channel group / cell group / terminal. When the setting is configured, the ARQ layer device may perform a lower-layer HARQ failure-based ARQ retransmission trigger operation only for ARQ PDUs whose remaining time is less than the remaining time threshold.

[0164] In one embodiment of the present disclosure, a base station may enable / disable a lower layer HARQ failure indication-based ARQ retransmission function for a specific ARQ layer device of a terminal (e.g., including the ID / LCID of the corresponding ARQ layer device indicating activation / deactivation), a plurality of ARQ layer devices (e.g., by setting a bit at a specific location to 1 or 0 in the form of a list or bitmap of the ID / LCID of the corresponding ARQ layer device indicating activation / deactivation, thereby indicating activation or deactivation of the ARQ layer device corresponding to the bit), or all ARQ layer devices (indicating activation or deactivation for all ARQ layer devices of the corresponding Cell Group / base station with a bit 1 or 0 or the (e)LCID of the corresponding MAC CE indicating activation / deactivation), through a predetermined MAC CE.

[0165] A transmitting device / receiving device providing ARQ and AHRQ functions according to one example of the present disclosure may be, for example, a terminal or a base station.

[0166] FIG. 5 is a block diagram illustrating the internal structure of a terminal according to one embodiment of the present disclosure.

[0167] Referring to FIG. 5, a terminal according to one example of the present disclosure includes an RF (Radio Frequency) processing unit (510), a baseband processing unit (520), a storage unit (530), and a control unit (540).

[0168] The RF processing unit (510) performs functions for transmitting and receiving signals through a wireless channel, such as signal band conversion and amplification. That is, the RF processing unit (510) up-converts the baseband signal provided by the baseband processing unit (520) 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 (510) may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC (digital to analog converter), an ADC (analog to digital converter), etc. Although only one antenna is shown in the drawing, the terminal may be equipped with multiple antennas. In addition, the RF processing unit (510) may include multiple RF chains. Furthermore, the RF processing unit (510) may perform beamforming. For the above beamforming, the RF processing unit (510) can adjust the phase and magnitude of each of the signals transmitted and received through multiple antennas or antenna elements. In addition, the RF processing unit can perform MIMO (multiple input multiple output) and can receive multiple layers when performing MIMO operation.

[0169] The baseband processing unit (520) performs a conversion function between a baseband signal and a bit sequence according to the physical layer specifications of the system. For example, when transmitting data, the baseband processing unit (520) generates complex symbols by encoding and modulating the transmitted bit sequence. Additionally, when receiving data, the baseband processing unit (520) restores the received bit sequence by demodulating and decoding the baseband signal provided by the RF processing unit (510). For example, in the case of following the OFDM (orthogonal frequency division multiplexing) method, when transmitting data, the baseband processing unit (520) generates complex symbols by encoding and modulating the transmitted bit sequence, maps the complex symbols to subcarriers, and then constructs OFDM symbols through IFFT (inverse fast Fourier transform) operation and CP (cyclic prefix) insertion. Additionally, upon receiving data, the baseband processing unit (520) divides the baseband signal provided by the RF processing unit (510) into OFDM symbol units, restores the signals mapped to subcarriers through a fast Fourier transform (FFT), and then restores the received bit sequence through demodulation and decoding.

[0170] The baseband processing unit (520) and the RF processing unit (510) transmit and receive signals as described above. Accordingly, the baseband processing unit (520) and the RF processing unit (510) may be referred to as a transmitting unit, a receiving unit, a transmitting and receiving unit, or a communication unit. Furthermore, at least one of the baseband processing unit (520) and the RF processing unit (510) may include a plurality of communication modules to support a plurality of different wireless access technologies. Additionally, at least one of the baseband processing unit (520) and the RF processing unit (510) may include different communication modules to process signals of different frequency bands. For example, the different wireless access technologies may include wireless LAN (e.g., IEEE 802.11), cellular network (e.g., LTE), etc. In addition, the above different frequency bands may include super high frequency (SHF) bands (e.g., 2 NRHz, NRHz) and millimeter wave (e.g., 60 GHz) bands.

[0171] The storage unit (530) stores data such as basic programs, application programs, and setting information for the operation of the terminal. In particular, the storage unit (530) can store information related to a second connection node that performs wireless communication using a second wireless connection technology. Additionally, the storage unit (530) provides the stored data upon the request of the control unit (540).

[0172] The control unit (540) controls the overall operations of the terminal. For example, the control unit (540) transmits and receives signals through the baseband processing unit (520) and the RF processing unit (510). Additionally, the control unit (540) writes and reads data to and from the storage unit (530). To this end, the control unit (540) may include at least one processor. For example, the control unit (540) may include a communication processor (CP) that performs control for communication and an application processor (AP) that controls upper layers such as applications.

[0173] FIG. 6 is a block diagram showing the configuration of an NR base station according to one embodiment of the present disclosure.

[0174] Referring to FIG. 6, a base station according to one example of the present disclosure is configured to include an RF processing unit (610), a baseband processing unit (620), a backhaul communication unit (630), a storage unit (640), and a control unit (650).

[0175] The RF processing unit (610) performs functions for transmitting and receiving signals through a wireless channel, such as signal band conversion and amplification. That is, the RF processing unit (610) upconverts the baseband signal provided by the baseband processing unit (620) into an RF band signal, transmits it through an antenna, and downconverts the RF band signal received through the antenna into a baseband signal. For example, the RF processing unit (610) may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, etc. Although only one antenna is shown in the drawing, the first connection node may be equipped with multiple antennas. Additionally, the RF processing unit (610) may include multiple RF chains. Furthermore, the RF processing unit (610) may perform beamforming. For beamforming, the RF processing unit (610) 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 (610) can perform down-to-down MIMO operation by transmitting one or more layers.

[0176] The baseband processing unit (620) performs a conversion function between a baseband signal and a bit sequence according to the physical layer specifications of the first wireless access technology. For example, when transmitting data, the baseband processing unit (620) generates complex symbols by encoding and modulating the transmitted bit sequence. In addition, when receiving data, the baseband processing unit (620) restores the received bit sequence by demodulating and decoding the baseband signal provided by the RF processing unit (610). For example, in the case of following the OFDM method, when transmitting data, the baseband processing unit (620) generates complex symbols by encoding and modulating the transmitted bit sequence, maps the complex symbols to subcarriers, and then constructs OFDM symbols through IFFT operation and CP insertion. Additionally, upon receiving data, the baseband processing unit (620) divides the baseband signal provided by the RF processing unit (610) into OFDM symbol units, restores the signals mapped to subcarriers through FFT operations, and then restores the received bit sequence through demodulation and decoding. The baseband processing unit (620) and the RF processing unit (610) transmit and receive signals as described above. Accordingly, the baseband processing unit (620) and the RF processing unit (610) may be referred to as a transmitting unit, a receiving unit, a transmitting and receiving unit, a communication unit, or a wireless communication unit.

[0177] The backhaul communication unit (630) provides an interface for communicating with other nodes within the network. That is, the backhaul communication unit (630) converts a bit sequence transmitted from the main base station to another node, e.g., an auxiliary base station, a core network, etc., into a physical signal, and converts a physical signal received from the other node into a bit sequence.

[0178] The storage unit (640) stores data such as basic programs, application programs, and configuration information for the operation of the main station. In particular, the storage unit (640) can store information regarding bearers assigned to connected terminals, measurement results reported from connected terminals, etc. Additionally, the storage unit (640) can store information that serves as a criterion for determining whether to provide or disconnect multiple connections to the terminals. Furthermore, the storage unit (640) provides the stored data in response to a request from the control unit (650).

[0179] The control unit (650) controls the overall operations of the main station. For example, the control unit (650) transmits and receives signals through the baseband processing unit (620) and the RF processing unit (610) or through the backhaul communication unit (630). Additionally, the control unit (650) writes and reads data to and from the storage unit (640). To this end, the control unit (650) may include at least one processor.

[0180] Methods according to the embodiments described in the claims or specification of the present invention may be implemented in the form of hardware, software, or a combination of hardware and software.

[0181] When implemented in software, a computer-readable storage medium may be provided for storing one or more programs (software modules). One or more programs stored in the computer-readable storage medium are configured for execution by one or more processors within an electronic device. One or more programs include instructions that cause the electronic device to execute methods according to embodiments described in the claims or specification of the present invention.

[0182] Such programs (software modules, software) may be stored in random access memory, non-volatile memory including flash memory, ROM (Read Only Memory), Electrically Erasable Programmable Read Only Memory (EEPROM), magnetic disc storage devices, Compact Disc-ROM (CD-ROM), Digital Versatile Discs (DVDs), or other forms of optical storage devices, magnetic cassettes. Alternatively, they may be stored in memory composed of some or all of these. Additionally, each constituent memory may include multiple units.

[0183] In addition, the above program may be stored on an attachable storage device that can be accessed via a communication network such as the Internet, Intranet, Local Area Network (LAN), Wide LAN (WLAN), or Storage Area Network (SAN), or a combination thereof. Such a storage device may be connected to a device performing an embodiment of the present invention through an external port. Additionally, a separate storage device on a communication network may be connected to a device performing an embodiment of the present invention.

[0184] In the specific embodiments of the present invention described above, the components included in the invention are expressed in a singular or plural form according to the specific embodiments presented. However, the singular or plural expression is selected to suit the situation presented for convenience of explanation, and the present invention is not limited to singular or plural components; even if a component is expressed in the plural form, it may be composed in the singular form, or even if a component is expressed in the singular form, it may be composed in the plural form.

[0185] Meanwhile, although specific embodiments have been described in the detailed description of the present invention, it is understood that various modifications are possible within the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined by the claims set forth below as well as equivalents thereof.

Claims

1. In a method of a transmitting device in a wireless communication system, A step of transmitting a packet to a receiving device through a first layer that supports a HARQ (hybrid automatic repeat request) function; A step of receiving HARQ information related to the packet transmission from the receiving device; If a HARQ failure is determined based on the above HARQ information, the step of transmitting instruction information indicating the HARQ failure from the first layer to the second layer supporting the ARQ (automatic repeat request) function; and In the second layer above, the method includes a step of triggering an ARQ retransmission based on the instruction information, and The above second layer is a layer above the above first layer, and A method of a transmitting device characterized in that the above instruction information is transmitted to an ARQ device that provided an ARQ PDU (protocol data unit) included in the packet among at least one ARQ device of the second layer.

2. In paragraph 1, the step of transmitting the instruction information is, In the first layer above, a step of verifying mapping information regarding the mapping between the packet and the ARQ device; and Based on the mapping information above, the method includes the step of transmitting the instruction information from the first layer to the ARQ device. A method of a transmitting device characterized in that the above mapping information indicates a mapping between the sequence number (SN) of the first layer PDU corresponding to the packet, the identity (ID) of the ARQ device, and the SN of the ARQ PDU.

3. In Paragraph 2, The step of transmitting the above packet further includes the step of transmitting resource information allocated to the ARQ layer device from the first layer to the ARQ device, the step of transmitting the ARQ PDU and control information related to the ARQ PDU from the ARQ device to the first layer based on the resource information, and the step of generating the above packet including the ARQ PDU at the first layer. The above mapping information is generated by the first layer based on the control information, and A method of a transmitting device characterized in that the above control information includes information about the SN of the ARQ PDU.

4. In Paragraph 3, If the ARQ PDU is a segment, the control information further includes at least one of byte information indicating the point where the segment was divided from the ARQ SDU (service data unit) or information regarding the length of the segment. A method of a transmitting device characterized in that the above byte information indicates at least one of the first byte or the last byte of the above segment.

5. In paragraph 1, the step of triggering the ARQ retransmission at the second layer is, A step of verifying mapping information regarding the mapping between the packet and the ARQ PDU based on the above instruction information; A step of identifying an ARQ SDU for retransmission based on the above-mentioned confirmed mapping information; and The method further includes the step of generating an ARQ PDU to be transmitted to the first layer based on the ARQ SDU identified above, and A method of a transmitting device characterized in that the above mapping information indicates a mapping between the sequence number (SN) of the first layer PDU corresponding to the packet and the SN of the ARQ PDU.

6. In Paragraph 5, The step of transmitting the above packet further includes the step of transmitting control information related to the packet from the first layer to the ARQ device and the step of generating the ARQ PDU in the ARQ layer device based on the control information. The above control information includes resource information allocated to the ARQ device and information regarding the PDU SN of the first layer corresponding to the packet, and A method of a transmitting device characterized in that the above mapping information is generated by the ARQ device based on the above control information.

7. In Paragraph 1, The first layer above is MAC (medium access control), the second layer above is RLC (radio link control), and the ARQ layer device is an RLC layer device set to AM (acknowledged mode). If the transmitting device is a base station and the receiving device is a terminal, the HARQ information is HARQ feedback information indicating a NACK (negative acknowledgment) for the packet transmission, and A method of a transmitting device characterized in that, if the transmitting device is the terminal and the receiving device is the base station, the HARQ information is information indicating the HARQ failure.

8. In a transmitting device in a wireless communication system, Transmitter / receiver; and A receiving device, comprising a control unit that controls the transmitting and receiving unit to transmit a packet through a first layer supporting a HARQ (hybrid automatic repeat request) function, controls the transmitting and receiving unit to receive HARQ information related to the packet transmission from the receiving device, and if a HARQ failure is determined based on the HARQ information, controls the first layer to transmit instruction information indicating the HARQ failure to a second layer supporting an ARQ (automatic repeat request) function, and controls the second layer to trigger an ARQ retransmission based on the instruction information. The above second layer is a layer above the above first layer, and A transmitting device characterized in that the above instruction information is transmitted to an ARQ device among at least one ARQ device of the second layer that provided the ARQ PDU (protocol data unit) included in the packet.

9. In Paragraph 8, The control unit checks mapping information regarding the mapping between the packet and the ARQ device in the first layer, and controls the transmission of instruction information to the ARQ device in the first layer based on the mapping information. A transmitting device characterized by the above mapping information indicating a mapping between the sequence number (SN) of the first layer PDU corresponding to the packet, the identity (ID) of the ARQ device, and the SN of the ARQ PDU.

10. In Paragraph 9, The control unit transmits resource information allocated to the ARQ layer device to the ARQ device in the first layer, transmits the ARQ PDU and control information related to the ARQ PDU from the ARQ device to the first layer based on the resource information, and controls the generation of the packet including the ARQ PDU in the first layer. The above mapping information is generated by the first layer based on the control information, and A transmitting device characterized in that the above control information includes information about the SN of the ARQ PDU.

11. In Paragraph 10, If the ARQ PDU is a segment, the control information further includes at least one of byte information indicating the point where the segment was divided from the ARQ SDU (service data unit) or information regarding the length of the segment. A transmitting device characterized in that the above byte information indicates at least one of the first byte or the last byte of the above segment.

12. In Paragraph 8, The control unit checks mapping information regarding the mapping between the packet and the ARQ PDU based on the instruction information, checks an ARQ SDU for retransmission based on the checked mapping information, and controls the second layer to generate an ARQ PDU to be transmitted to the first layer based on the checked ARQ SDU. A transmitting device characterized in that the above mapping information indicates a mapping between the sequence number (SN) of the first layer PDU corresponding to the packet and the SN of the ARQ PDU.

13. In Paragraph 12, The control unit transmits control information related to the packet to the ARQ device in the first layer, and controls the ARQ layer device to generate the ARQ PDU based on the control information. The above control information includes resource information allocated to the ARQ device and information regarding the PDU SN of the first layer corresponding to the packet, and A transmitting device characterized in that the above mapping information is generated by the ARQ device based on the above control information.

14. In Paragraph 8, The first layer above is MAC (medium access control), the second layer above is RLC (radio link control), and the ARQ layer device is an RLC layer device set to AM (acknowledged mode). If the transmitting device is a base station and the receiving device is a terminal, the HARQ information is HARQ feedback information indicating a NACK (negative acknowledgment) for the packet transmission, and A transmitting device characterized in that, if the transmitting device is the terminal and the receiving device is the base station, the HARQ information is information indicating the HARQ failure.

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