Method and apparatus for discarding PDCP SDU in wireless communication system

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. The present disclosure relates to an operation method of a terminal in a wireless communication system, comprising the steps of: receiving a terminal capability request message from a base station; transmitting terminal capability information including information related to discarding the PDU set to the base station in response to the terminal capability request message; and receiving configuration information on the PDU set from the base station when the terminal supports discarding of the PDU set.

Description

Technical Field

[0001] The present disclosure relates to operations of a UE in a wireless communication system. More particularly, the present disclosure relates to a method and apparatus for efficiently serving application data services in a wireless communication system. Background Art

[0002] 5G mobile communication technology defines a wide frequency band, making high transmission rates and new services possible, and can be implemented not only in "below 6 GHz" frequency bands such as 3.5 GHz, but also in "above 6 GHz" frequency bands called millimeter waves including 28 GHz and 39 GHz. In addition, it has been considered to implement 6G mobile communication technology (called Beyond 5G system) in terahertz (THz) frequency bands (e.g., 95 GHz to 3 THz frequency bands) in order to achieve a transmission rate 50 times faster than 5G mobile communication technology and an ultra-low latency of one tenth of 5G mobile communication technology.

[0003] At the beginning of the development of 5G mobile communication technology, in order to support services and meet performance requirements related to enhanced mobile broadband (eMBB), ultra-reliable low-latency communication (URLLC) and massive machine type communication (mMTC), standardization is underway on the following items: beamforming and massive MIMO for reducing radio wave path loss and increasing radio wave transmission distance in millimeter waves, parameter sets supporting efficient utilization of millimeter wave resources and dynamic operation of time slot formats (for example, operating multiple subcarrier spacings), initial access technology for supporting multi-beam transmission and broadband, definition and operation of BWP (bandwidth part), new channel coding methods (such as LDPC (low-density parity check) codes for large-scale data transmission) and polarization codes for highly reliable transmission of control information, L2 preprocessing, and network slicing for providing dedicated networks dedicated to specific services.

[0004] Currently, in view of the services to be supported by the 5G mobile communication technology, discussions on improvements and performance enhancements of the initial 5G mobile communication technology are underway, and there is already physical layer standardization on technologies such as V2X (Vehicle to Everything) for assisting driving determination of autonomous vehicles based on information about the position and status of the vehicle sent by the vehicle and for enhancing user convenience, NR-U (New Radio Unlicensed) for system operation designed to comply with various regulation-related requirements in unlicensed bands, NR UE energy saving, non-terrestrial network (NTN) as UE-satellite direct communication for providing coverage in areas where communication with terrestrial networks is unavailable, and positioning.

[0005] In addition, there has been standardization in the air interface architecture / protocol on technologies such as the Industrial Internet of Things (IIoT) for supporting new services through interworking and integration with other industries, IAB (Integrated Access and Backhaul) for providing nodes for network service area expansion by supporting wireless backhaul links and access links in an integrated manner, mobility enhancements including conditional handover and DAPS (Dual Active Protocol Stack) handover, and two-step random access (2-step RACH for NR) for simplifying the random access process. There is also continuous standardization of the 5G baseline architecture (e.g., service-based architecture or service-based interface) for combining network function virtualization (NFV) and software defined network (SDN) technologies, and the system architecture / services for mobile edge computing (MEC) for receiving services based on UE location.

[0006] With the commercialization of 5G mobile communication systems, an exponentially growing number of connected devices will be connected to the communication network, so it is expected that enhanced functions and performance of 5G mobile communication systems and integrated operations of connected devices will be necessary. To this end, new research is arranged in conjunction with extended reality (XR) to effectively support AR (augmented reality), VR (virtual reality), MR (mixed reality), etc., to improve 5G performance and reduce complexity by utilizing artificial intelligence (AI) and machine learning (ML), AI service support, metadata service support, and drone communication.

[0007] In addition, such development of 5G mobile communication systems will serve not only as a basis for developing new waveforms for providing coverage in the terahertz band of 6G mobile communication technology, multi-antenna transmission technologies such as full-dimensional MIMO (FD-MIMO), array antennas, and massive antennas, metamaterial-based lenses and antennas for improving coverage of terahertz band signals, high-dimensional spatial multiplexing technology using OAM (orbital angular momentum), and RIS (reconfigurable smart surfaces), but also as a basis for developing full-duplex technology for improving the frequency efficiency of 6G mobile communication technology and improving system networks, AI-based communication technology for achieving system optimization by utilizing satellites and AI (artificial intelligence) from the design stage and internalizing end-to-end AI support functions, and next-generation distributed computing technology for implementing services at a complexity level that exceeds the limitations of UE operating capabilities by utilizing ultra-high performance communication and computing resources.

[0008] As described above, wireless communication systems can provide various services, and thus methods for efficiently providing these services are required. Summary of the invention

[0009] Technical issues

[0010] The embodiments described herein are intended to provide a device and method capable of effectively providing services in a wireless communication system.

[0011] Solution to the problem

[0012] According to an embodiment of the present disclosure, a method performed by a terminal in a wireless communication system may include: receiving a terminal capability query message from a base station; in response to the capability query message, sending terminal capability information including information related to a discarded protocol data unit (PDU) set to the base station; and when the terminal supports discarding the PDU set, receiving configuration information about discarding the PDU set from the base station.

[0013] Advantageous Effects of the Invention

[0014] The present disclosure provides an apparatus and method capable of effectively providing a service in a wireless communication system. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1a The structure of the NR system according to an embodiment of the present disclosure is shown.

[0016] Figure 1b The wireless protocol structure in the LTE and NR systems according to an embodiment of the present disclosure is shown.

[0017] Figure 1c A configuration of a protocol data unit (PDU) set with respect to each application data unit (ADU) according to an embodiment of the present disclosure is shown.

[0018] Figure 1d The PDU set discarding operation and configuration method on the Packet Data Convergence Protocol (PDCP) layer according to an embodiment of the present disclosure are shown.

[0019] Figure 1e The present invention shows a PDU set discarding operation and configuration method in the case where the individual PDUs constituting the PDU set have different importance levels according to an embodiment of the present disclosure.

[0020] Figure 1f The PDU set discarding operation and configuration method according to an embodiment of the present disclosure are shown in the case where there is dependency between PDU sets.

[0021] Figure 1g A signaling process between a UE and a base station according to an embodiment of the present disclosure is shown, which is used to configure a PDU set discard operation on the PDCP layer of the UE.

[0022] Figure 2 A UE device according to an embodiment of the present disclosure is shown.

[0023] Figure 3 A base station device according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0024] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. When describing the present disclosure below, when it is determined that the description may make the subject matter of the present disclosure unnecessarily unclear, a detailed description of known functions or configurations contained herein will be omitted. The terms to be described below are terms defined in consideration of the functions in the present disclosure, and may differ depending on the user, the user's intention or custom. Therefore, the definition of the terms should be based on the content of the entire specification.

[0025] By referring to the embodiments described in detail below in conjunction with the accompanying drawings, the advantages and features of the present disclosure and the methods for achieving them will become clear. However, the present disclosure is not limited to the embodiments set forth below, but can be implemented in various different forms. The following embodiments are provided only to fully disclose the present disclosure and inform those skilled in the art of the scope of the present disclosure, and the present disclosure is limited only by the scope of the attached claims. Throughout the specification, the same or similar reference numerals represent the same or similar elements.

[0026] In this article, it will be understood that each box of the flowchart diagram and the combination of boxes in the flowchart diagram can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device create a device for implementing the functions specified in one or more flowchart boxes. These computer program instructions can also be stored in a computer-available or computer-readable memory, which can guide the computer or other programmable data processing device to run in a specific manner, so that the instructions stored in the computer-available or computer-readable memory produce products including instruction devices that implement the functions specified in one or more flowchart boxes. Computer program instructions can also be loaded on a computer or other programmable data processing device so that a series of operating steps are performed on a computer or other programmable device to produce a computer-implemented process so that the instructions executed on a computer or other programmable device provide steps for implementing the functions specified in one or more flowchart boxes.

[0027] In addition, each frame of the flowchart diagram can represent a module, segment or part of a code, which includes one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions mentioned in the frame may not occur in order. For example, depending on the functions involved, two frames shown in succession can actually be performed substantially simultaneously, or these frames can sometimes be performed in reverse order.

[0028] As used in the embodiments of the present disclosure, the term "unit" refers to a software element or a hardware element such as a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC), and a "unit" can perform certain functions. However, a "unit" does not always have a meaning limited to software or hardware. A "unit" can be constructed to be stored in an addressable storage medium or to execute one or more processors. Therefore, a "unit" includes, for example, a software element, an object-oriented software element, a class element or a task element, a process, a function, a property, a process, a subroutine, a fragment of a program code, a driver, a firmware, a microcode, a circuit, data, a database, a data structure, a table, an array, and a parameter. The elements and functions provided by a "unit" can be combined into a smaller number of elements or "units", or divided into a larger number of elements or "units". In addition, elements and "units" can be implemented as one or more CPUs in a reproduction device or a secure multimedia card. In addition, a "unit" in an embodiment can include one or more processors.

[0029] In describing the following disclosure, a detailed description of known functions or configurations included herein will be omitted when it is determined that the description may make the subject matter of the present disclosure unnecessarily unclear. Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0030] In the following description, for the convenience of description, terms used to identify access nodes, terms referring to network entities, terms referring to messages, terms referring to interfaces between network entities, terms referring to various identification information, etc. are exemplarily used. Therefore, the present disclosure is not limited to the following terms, and other terms referring to subjects with equivalent technical meanings may also be used.

[0031] In the following description, the terms "physical channel" and "signal" may be used interchangeably with the terms "data" or "control signal". For example, the term "physical downlink shared channel (PDSCH)" refers to a physical channel through which data is transmitted, but PDSCH may also be used to refer to "data". That is, in the present disclosure, the expression "transmission physical channel" may be interpreted as having the same meaning as the expression "transmitting data or signal through a physical channel".

[0032] In the following description of the present disclosure, upper layer signaling refers to a signal transmission scheme from a base station to a terminal via a downlink data channel of a physical layer or a signal transmission scheme from a terminal to a base station via an uplink data channel of a physical layer. Upper layer signaling can also be understood as radio resource control (RRC) signaling or media access control (MAC) control element (CE).

[0033] In the following description of the present disclosure, for the convenience of description, the terms and names defined in the 3rd Generation Partnership Project New Radio (3GPP NR) or 3GPP Long Term Evolution (3GPP LTE) standards will be used. However, the present disclosure is not limited to these terms and names, and can be applied to systems that comply with other standards in the same manner. In the present disclosure, for the convenience of description, the term "gNB" can be used interchangeably with the term "eNB". That is, a base station described as an "eNB" can refer to a "gNB". In addition, the term "terminal" can refer not only to mobile phones, MTC devices, NB-IoT devices, and sensors, but also to other wireless communication devices.

[0034] In the following description, a base station is an entity that allocates resources to a terminal, and may be at least one of a gNode B (gNB), an eNode B (eNB), a Node B, a base station (BS), a wireless access unit, a base station controller, and a node on a network. A terminal may include a user equipment (UE), a mobile station (MS), a cellular phone, a smart phone, a computer, or a multimedia system capable of performing a communication function. Of course, examples of base stations and terminals are not limited to those described above.

[0035] The present disclosure relates to a method and apparatus for discarding a packet data convergence protocol service data unit (hereinafter referred to as PDCP SDU discard) in a next generation wireless communication system. More specifically, the present disclosure relates to a method and apparatus, wherein, when a group of protocol data units (PDUs) (hereinafter referred to as PDU sets) corresponding to an application data unit (hereinafter referred to as ADU) is configured in 3GPP5GS, a PDCP SDU discard operation is performed for each PDU set so as to effectively use network radio resources.

[0036] The present disclosure proposes various protocol data unit (PDU) set configurations that can be used to ensure ADU-unit quality of service (QoS), and describes a method for adaptively performing a PDU set discard operation according to various PDU set configurations. In order to describe the method for performing a PDU set discard operation, a method for indicating a PDU set discard operation for each PDU set on a PDCP layer and a method for indicating a PDU set discard operation for each PDU will be described in detail. In addition, considering the dependencies between PDU sets, a PDU set discard operation is defined.

[0037] Through the present disclosure, the UE and the base station can exchange control information for the PDU set discard operation. The UE can report to the base station (e.g., gNB) whether the PDU set discard operation is supported through the UE capability information. The base station (e.g., gNB) can refer to the UE capability information reported by the UE to instruct the UE to perform the PDU set discard operation, and the UE can perform the PDU set discard operation according to the instruction of the base station.

[0038] Figure 1a The structure of the NR system according to an embodiment of the present disclosure is shown.

[0039] refer to Figure 1a , the wireless communication system may be configured by a plurality of base stations (e.g., gNB 105, ng-eNB 110, ng-eNB 115, and gNB 120), an access and mobility management function (AMF) 125, and a user plane function (UPF) 130. A user equipment (hereinafter referred to as UE or terminal) 135 may access an external network through the base stations (e.g., gNB 105, ng-eNB 110, ng-eNB 115, and gNB 120) and the UPF 130.

[0040] exist Figure 1a In the figure, base stations (e.g., gNB 105, ng-eNB 110, ng-eNB 115, and gNB 120) can act as cellular network access nodes to provide wireless access to UEs accessing the network. That is, base stations (e.g., gNB 105, ng-eNB110, ng-eNB 115, and gNB 120) can aggregate and schedule status information such as the buffer status of the UE, the available transmission power status, and the channel status to provide services for the user's business, thereby supporting the connection between the UE and the core network (CN). At the same time, the control plane (CP) for managing the connection and the user plane (UP) related to the transmission of actual user data during communication can be divided and configured. In the figure, gNB 105 and gNB 120 can use the UP and CP technologies defined in the NR technology, and although connected to 5GC, ng-eNB 110 and ng-eNB 115 can use the UP and CP technologies defined in the LTE technology. 5GC can refer to the CN in the NR system.

[0041] The AMF 125 may refer to a device configured to process various control functions other than UE-related mobility management functions, and may be connected to a plurality of base stations. The UPF 130 may refer to a gateway device configured to provide data transmission. Figure 1a Not shown, the NR 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 the UE.

[0042] Figure 1b The wireless protocol structure in the LTE and NR systems according to an embodiment of the present disclosure is shown.

[0043] refer to Figure 1b, the radio protocol of the NR system may include service data adaptation protocol (SDAP) 100 and 145 on the UE side and the gNB side, packet data convergence protocol (PDCP) 105 and 140, radio link control (RLC) 110 and 135, and medium access control (MAC) 115 and 130, respectively. SDAP 100 and 145 may perform operations for mapping each QoS flow to a specific data radio bearer (DRB), and may give an SDAP configuration corresponding to each DRB from an upper layer (e.g., RRC layer). PDCP 105 and 104 may handle operations such as IP header compression and / or recovery, and RLC 110 and 135 may reconfigure the PDCP PDU to an appropriate size. MAC 115 and 130 may be connected to a plurality of RLC layer devices configured for one UE, and may perform operations for multiplexing RLC PDUs to MAC PDUs and demultiplexing RLC PDUs from MAC PDUs. The physical (PHY) layers 120 and 125 may perform the following operations: channel coding and modulating upper layer data, generating orthogonal frequency division multiplexing (OFDM) symbols therefrom and transmitting them through a wireless channel, or demodulating OFDM symbols received through a wireless channel, channel decoding them, and passing them to an upper layer. In addition, the PHY layers 120 and 125 may perform additional error correction using a hybrid automatic repeat request (HARQ), and the receiving end may send a bit to the transmitting end to indicate whether the packet transmitted thereby has been received. Information on whether the receiving end has received a packet from the transmitting end may be referred to as HARQ ACK / NACK information. In the case of an LTE system, downlink HARQ ACK / NACK information regarding uplink data transmission may be transmitted through a physical HARQ indicator channel (PHICH). In the case of an NR system, downlink HARQ ACK / NACK information regarding uplink data transmission may be transmitted through a physical dedicated control channel (PDCCH) for transmitting downlink and / or uplink resource allocation, etc., and the base station may determine whether retransmission is required or whether a new transmission is to be performed based on the scheduling information of the UE. Unlike LTE, the reason why the base station in the NR system determines whether retransmission is required or whether new transmission is to be performed based on the scheduling information of the UE is because asynchronous HARQ is applied in NR. Uplink HARQ ACK / NACK information about downlink data transmission can be transmitted through the physical uplink control channel (PUCCH) or through the physical uplink shared channel (PUSCH). PUCCH can generally be transmitted in the uplink of the primary cell (PCell) (described later). However, if the UE supports it, HARQ ACK / NACK information about the secondary cell (SCell) (described later) can be sent, and the SCell can be called a PUCCH SCell.

[0044] Although not shown in the drawing, a radio resource control (RRC) layer may exist on each upper layer of the PDCP layer of the UE and the base station, and the RRC layer may exchange access / measurement-related configuration control messages for radio resource control.

[0045] Meanwhile, the PHY layer may be configured by one or more frequencies and / or carriers, and a technique in which multiple frequencies are configured and used simultaneously may be referred to as carrier aggregation (CA). According to the CA technique, instead of using only one carrier for communication between a UE and a base station (e.g., an eNB or gNB), a primary carrier and one or more subcarriers may be additionally used to increase the amount of transmission as much as the number of subcarriers. Meanwhile, a cell in a base station using a primary carrier in LTE and NR systems may be referred to as a primary cell or PCell, and a cell in a base station using a subcarrier may be referred to as a secondary cell or SCell.

[0046] Figure 1c A configuration of a PDU set for each application data unit (ADU) according to an embodiment of the present disclosure is shown.

[0047] refer to Figure 1c , various services can be distinguished by ADU, which is an information unit distinguishable at the application level. In an embodiment, the ADU can be a photo or picture, a frame of video, or an audio unit. The ADU can be distinguished for each PDU set 110, and the PDU set 110 can be divided into one or more PDUs 101, 102, 103, 104, 105, and 106, and then transmitted according to size.

[0048] For example, in the case where the Moving Picture Experts Group (MPEG) standard video compression technology is used for video services, the PDU set may be configured by one of the following: 1) a combination 130 of multiple PDUs corresponding to an intra (I) frame; 2) a combination 140 of multiple PDUs corresponding to a bidirectional (B) frame; 3) a combination 150 of multiple PDUs corresponding to a predictive (P) frame; and 4) a combination 160 of multiple PDUs corresponding to an ADU configured by multiple I frames 161, B frames 162 and 164, and / or P frames 163. The I frame 120 is an independent frame and may represent a complete photo or picture 121 regardless of whether other frames exist. The P frame and the B frame 122 represent information about changes in the previous I frame 120. If the I frame 120 is not received normally, the photo or picture 123 to be expressed by the P frame and the B frame 122 may not be expressed normally. In addition, the B frame is placed between the I frame and the P frame, so the motion between the two frames is stored as prediction data with reference to the two frames. Therefore, only when both the I frame (before it) and the P frame (after it) are received normally, the photo or picture to be expressed by the B frame can be expressed normally.

[0049] In the embodiments of the present disclosure, for ease of description, the PDU set configuration and PDU set discard (or ADU discard) operation may be described with reference to an exemplary case in which the MPEG standard video compression technology is used for a video service. However, the content of the present disclosure is not limited to the PDU set configuration associated with the video service, and may be applied to all normal ADU-based PDU set configurations.

[0050] Figure 1d The PDU set discarding operation and configuration method on the PDCP layer according to an embodiment of the present disclosure are shown.

[0051] In the case where a discard timer (discardTimer) is configured for a PDCP entity for a specific DRB used to transmit delay-time-sensitive services, and in the case where the PDCP entity for which the discardTimer is configured has received a PDCP SDU from an upper layer, the discardTimer associated with the PDCP SDU may be started. In the case where the discardTimer expires before the PDCP SDU is successfully transmitted, the PDCP entity may abandon the transmission and discard the PDCP SDU. In addition, in the case where the PDCP SDU has been delivered to a lower layer for transmission, the PDCP entity may instruct the lower layer to discard the PDCP PDU corresponding to the PDCP SDU. The PDU set discard operation on the above-mentioned PDCP layer may be configured in the following circumstances: when a delay-time-sensitive service is transmitted, the delayed transmission of the PDCP SDU has no effect on the receiving end from the point in time when the discardTimer configured at a specific time value expires.

[0052] refer to Figure 1d In the case where a specific PDU 102 among the PDUs constituting the PDU set 100 has been discarded due to the expiration of the discardTimer, the PDCP layer may perform a PDU set discard operation, wherein the remaining PDUs 101, 103, 104, 105, and 106 constituting the PDU set are discarded in order to effectively use the radio resources. The remaining PDUs may refer to "PDUs that have not yet been transmitted" among the PDUs constituting the PDU set, or may refer to "PDUs having a sequence number (SN) higher than the discarded PDU". In addition, the "PDU set" and "PDU" used in this document may refer to PDUs on the PDCP upper layer, or may refer to PDCP SDUs on the PDCP layer. Such a PDU set discard operation (or ADU discard) can achieve effective use of radio resources, because even if one of the PDUs constituting the PDU set is discarded, thereby making the PDU set transmission meaningless, the other PDUs belonging to the PDU set will also be discarded.

[0053] The PDU set discard operation can be configured for each DRB. In order to configure the PDU set discard operation, a 1-bit indicator can be newly defined in the PDCP-Config of the DRB, such as "PDU_Set DiscardEnabled", "PDU_SetDiscard", "ADU_DiscardEnabled", "A DU_Discard", etc., and the base station can configure the PDU set discard operation for a specific DRB through the newly defined indicator in the PDCP-Config of the DRB. In addition, the base station can pass to the UE a list of IDs of the DRBs on which it is to perform the PDU set discard operation, and the UE can perform the PDU set discard operation in the PDCP entity corresponding to the DRB. In addition, the base station can configure the PDU set discard operation for each UE instead of configuring the PDU set discard operation for each DRB. When the PDU set discard operation is configured for each UE, the base station can pass a 1-bit indicator (such as "PDU_SetDiscardEnabled", "PDU_SetDiscard", "ADU_DiscardEnabled", "ADU_Discard", etc.) to the specific UE to configure the PDU set discard operation. Upon receiving the 1-bit indicator, the UE can perform the PDU set discard operation for the DRBs in all DRBs configured in the UE (the DRBs have a discardTimer configured for them and have received PDU set related configuration information (e.g., PDU set index information) from the upper layer).

[0054] As in the above-mentioned embodiment, a PDU set discard operation can be configured for each DRB, and in the case where the PDU set discard operation is configured for each DRB, the PDU set discard operation can be performed for all PDU sets transmitted through the DRB. However, in the case where various PDU sets (for example, PDU sets corresponding to I frames, B frames, and P frames, respectively) are sent together through the same DRB, whether a PDU set discard operation is required may vary depending on the type of PDU set. For example, in the case where a specific PDU 111 of a PDU set 110 configured by PDUs constituting an I frame is discarded due to the expiration of a discardTimer, it is difficult to recover the I frame even if all other PDUs belonging to the PDU set are received. Therefore, in the case where it is difficult to recover the I frame, the PDCP entity can perform a PDU set discard operation on the PDU set corresponding to the I frame to prevent meaningless use of wireless resources. On the other hand, in the case where a PDU set 120 constitutes a B frame, even if a specific PDU 121 in the PDU set is discarded due to the expiration of a discardTimer, the B frame can be recovered. However, the quality of the recovered B frame may deteriorate in proportion to the number of PDUs discarded in the PDUs constituting the PDU set, so the PDCP entity may not perform a PDU set discard operation on the PDU set corresponding to the B frame. Depending on whether the PDU set discard operation is necessary, the manner of operating the discardTimer on the PDCP layer may be different. In the case where the PDUs (e.g., PDCP SDUs) constituting the type of PDU set that requires a PDU set discard operation have arrived at the PDCP layer, the PDCP entity may operate the discardTimer for each PDU set so as to perform a discard operation for each PDU set. Specifically, at a point in time when the first PDU constituting a specific PDU set has arrived at the PDCP layer, the PDCP entity may start the discardTimer corresponding to the PDU set. Thereafter, if the discardTimer corresponding to the PDU set expires, the PDCP entity may discard all PDUs (e.g., PDCP SDUs) constituting the PDU set. On the other hand, in the case where PDUs (e.g., PDCP SDUs) constituting a PDU set type that does not require a PDU set discard operation have arrived at the PDCP layer, the PDCP entity may operate a discardTimer for each PDU (e.g., PDCP SDN) regardless of the PDU set. Specifically, at the time point when each PDU (e.g., PDCP SDU) has arrived at the PDCP layer, the PDCP layer may start a discardTimer corresponding to the PDU. Thereafter, if the discardTimer corresponding to each PDU set expires, the PDCP layer may discard the corresponding PDU.In addition, a scheme can be considered in which, in the case where the PDUs (e.g., PDCP SDUs) constituting the PDU set type that requires a PDU set discard operation have arrived at the PDCP layer, the PDCP entity also operates the discardTimer for each PDU. In the case of a scheme in which the PDCP entity operates the discardTimer for each PDU, the PDCP layer can start the discardTimer corresponding to the PDU at a time point when each PDU (e.g., PDCP SDU) constituting a specific PDU set has arrived at the PDCP layer. Thereafter, if the discardTimer corresponding to a specific PDU (e.g., PDCP SDU) constituting a specific PDU set expires, the PDCP entity can discard all PDUs (e.g., PDCP SDUs) constituting the PDU set. However, if the discardTimer is also operated for each PDU for the PDUs constituting the PDU set type that requires a PDU set discard operation, the actual PDCP discard may be performed for each PDU set. This may result in the inefficiency of operating each timer unnecessarily for each PDU.

[0055] As in the above embodiment, whether to perform a PDCP discard operation may vary depending on the type of the PDU set (for example, depending on which of the I frame, B frame or P frame the PDU set corresponds to). For each PDU set, the following method may be used to indicate to the PDCP layer whether to perform a PDU set discard operation on the PDU set:

[0056] Method 1: A 1-bit indicator (e.g., "PDU_SetDiscard", "ADU_discard", etc.) may be given to indicate whether PDU set discard needs to be performed for each PDU set. If the ADU_discard indicator value is given as "true" or "enabled" for a specific PDU set (133 or 135), the PDCP entity may perform a PDU set discard operation for the PDU set. On the other hand, if the ADU_discard indicator value is given as "false" or "disabled" for a specific PDU set (130), the PDCP entity may not perform a PDU set discard operation for the PDU set.

[0057] In order to indicate to the PDCP entity whether a PDU set discard operation is required for each PDU set, the SDAP header may include an indicator indicating whether a PDU set discard operation is required and PDU set index information. The indicator may be included in the SDAP headers of all PDUs constituting the PDU set, or may be included in the SDAP header of the first PDU constituting the PDU set. In the case where the PDU set discard indicator is only included in the SDAP header of the first PDU constituting the PDU set, the packet processing load on the SDAP / PDCP layer can be reduced. However, in the event that a problem occurs when processing the first PDU of the PDU set, problems may also arise with respect to the configuration of the PDU set discard operation. The SDAP layer may receive information from an upper layer (e.g., an application layer, an IP layer, or a non-access layer) regarding whether a PDU set discard operation is required for each PDU set, as well as information about the PDU set configuration.

[0058] Method 2: An indicator (e.g., PDU_SetType, etc.) may be given to indicate the type of each PDU set. In addition, the PDU set type 147 for which a PDU set discard operation needs to be performed: 1) may be given from the non-access stratum (NAS) layer; 2) may be pre-configured for the UE side; or 3) may be given (or configured) through RRC signaling. In the case where the PDU_SetType value given for a specific PDU set corresponds to the PDU set type for which a PDU set discard operation needs to be performed (143 or 145), the PDCP entity may perform a PDU set discard operation for the PDU set. On the other hand, in the case where the PDU_SetType value given for a specific PDU set does not correspond to the PDU set type for which a PDU set discard operation needs to be performed (140), the PDCP entity may not perform a PDU set discard operation for the PDU set.

[0059] In order to indicate the type of each PDU set (e.g., PDU_SetType) to the PDCP entity, the SDAP header may include an indicator indicating the PDU set type (PDU_SeType) and PDU set index information. The indicator may be included in the SDAP headers of all PDUs constituting the PDU set, or may be included in the SDAP header of the first PDU constituting the PDU set. In the case where the PDU set type indicator is included only in the SDAP header of the first PDU constituting the PDU set, the packet processing load on the SDAP / PDCP layer may be reduced. However, in the event that a problem occurs when processing the first PDU of a PDU set, problems may also arise with respect to the configuration of the PDU set discard operation.

[0060] The SDAP layer may receive information about the PDU set type and information about the PDU set configuration from an upper layer (eg, an application layer, an IP layer, or a non-access layer).

[0061] Method 3: An indicator (e.g., ImportanceLevel, etc.) may be given to indicate the importance level of each PDU set. In addition, a threshold value of the importance level for which a PDU set discard operation is to be performed (e.g., ADU discard threshold) 157: 1) may be given from the non-access stratum (NAS) layer; 2) may be pre-configured for the UE side; or 3) may be given (or configured) through RRC signaling. In the case where the value of the importance level (ImportanceLevel) given for a specific PDU set is greater than the threshold value of the importance level for which a PDU set discard operation is to be performed (150), the PDCP entity may perform a PDU set discard operation for the PDU set. On the other hand, in the case where the value of the importance level (ImportanceLevel) given for a specific PDU set is less than or equal to the threshold value of the importance level for which a PDU set discard operation is to be performed (153 or 155), the PDCP entity may not perform a PDU set discard operation for the PDU set.

[0062] In order to indicate the importance level of each PDU set to the PDCP entity, the SDAP header may include an indicator (ImportanceLevel) indicating the importance level of the PDU set and the PDU set index information. The indicator may be included in the SDAP headers of all PDUs constituting the PDU set, or may be included in the SDAP header of the first PDU constituting the PDU set. In the case where the PDU set importance level indicator is included only in the SDAP header of the first PDU constituting the PDU set, the packet processing load on the SDAP / PDCP layer can be reduced. However, in the event that a problem occurs when processing the first PDU of a PDU set, problems may also occur with respect to the configuration of the PDU set discard operation.

[0063] The SDAP layer may receive information about the importance level of the PDU set and information about the PDU set configuration from an upper layer (eg, an application layer, an IP layer, or a non-access layer).

[0064] Figure 1e The present invention shows a PDU set discarding operation and configuration method in the case where the individual PDUs constituting the PDU set have different importance levels according to an embodiment of the present disclosure.

[0065] refer to Figure 1e, the PDUs constituting the same PDU set may have different importance levels. In addition, in the case where the PDU has been discarded according to the importance level of each PDU, whether other PDUs belonging to the same PDU set are also to be discarded (for example, whether a PDU set discard operation needs to be performed) may be different. For example, in the case where the PDU set 100 or 105 corresponds to an ADU configured by multiple I frames, B frames, and P frames, the importance level may vary depending on the type of frame configured by each PDU constituting the PDU set, and whether a PDU set discard operation needs to be performed together when the PDU is discarded may also be different. As in 100, in the case where the PDU 101 constituting the I frame is discarded due to the expiration of the discardTimer, the I frame and the B frame and P frame that reference the I frame may not be restored. Therefore, in the case where the I frame and the B frame and P frame that reference the I frame cannot be restored, discarding the PDU 101 corresponding to the I frame may result in a PDU set discard operation with respect to the PDU set 100. On the other hand, in the case where the PDU 106 constituting the B frame is discarded due to the expiration of the discardTimer, as in 105, the quality of the restored B frame may be reduced, but it is possible to restore the I frame and the P frame included together in the same PDU set. Therefore, in the case where the PDU 106 constituting the B frame is discarded due to the expiration of the discardTimer, discarding the PDU 106 corresponding to the B frame may not easily cause a PDU set discard operation with respect to the PDU set 105.

[0066] As in the above embodiment, in the case where each PDU belonging to the same PDU set has a different importance level, it may be necessary to indicate to the PDCP layer whether discarding each PDU due to the expiration of the discardTimer will result in a PDU set discard operation of the PDU set to which the PDU belongs. There may be the following method to indicate to the PDCP layer whether discarding each PDU due to the expiration of the discardTimer will result in a PDU set discard operation of the PDU set to which the PDU belongs.

[0067] Method 1: A 1-bit indicator (e.g., "PDU_SetDiscard_trigger", "ADU_discard_ctrigger", etc.) may be given to indicate whether a PDU set discard operation may be generated for each PDU. If the ADU_discard_trigger indicator value is given as "true" or "enabled" for a specific PDU (111), the PDCP entity may perform a PDU set discard operation when the PDU is discarded due to expiration of the discardTimer value. On the other hand, if the ADU_discard_trigger indicator value is given as "false" or "disabled" for a specific PDU (112, 113, or 114), the PDCP entity may have difficulty performing a PDU set discard operation when the PDU is discarded due to expiration of the discardTimer value.

[0068] In order to indicate to the PDCP entity whether a PDU set discard operation can be generated for each PDU, the SDAP header may include an indicator indicating whether a PDU set discard operation needs to occur. The indicator may be included in the SDAP headers of all PDUs constituting the PDU set. The SDAP layer may receive information about whether a PDU set discard operation needs to be performed for each PDU, as well as information about the PDU set configuration, from an upper layer (e.g., an application layer, an IP layer, or a non-access layer).

[0069] Method 2: An indicator (e.g., PDU_Type, etc.) may be given to indicate the type of each PDU. In addition, the PDU type 125 (a list of PDU_type values) that may cause a PDU set discard operation: 1) may be given from the non-access stratum (NAS) layer; 2) may be pre-configured for the UE side; or 3) may be given (or configured) through RRC signaling. In the case where the PDU_Type value given for a specific PDU corresponds to a PDU type (121) that causes a PDU set discard operation, the PDCP entity may perform a PDU set discard operation while discarding the PDU when the discardTimer of the PDU expires. On the other hand, in the case where the PDU_Type value given for a specific PDU does not correspond to a PDU type (122, 123, or 124) that causes a PDU set discard operation, the PDCP entity may have difficulty in performing a PDU set discard operation while discarding the PDU when the discardTimer of the PDU expires.

[0070] In order to indicate the type of each PDU (eg, PDU_type) to the PDCP entity, the SDAP header may include an indicator indicating the PDU type (PDU_Type). The indicator may be included in the SDAP headers of all PDUs constituting the PDU set.

[0071] The SDAP layer may receive information about a PDU type and information about a PDU set configuration from an upper layer (eg, an application layer, an IP layer, or a non-access layer).

[0072] Method 3: An indicator (e.g., ImportanceLevel, etc.) may be given to indicate the importance level of each PDU. In addition, the threshold 137 (ADU discard threshold) of the importance level at which the PDU set discard operation may occur: 1) may be given from the non-access stratum (NAS) layer; 2) may be pre-configured for the UE side; or 3) may be given (or configured) by RRC signaling. In the case where the value of the importance level (ImportanceLevel) given for a specific PDU is greater than the threshold of the importance level at which the PDU set discard operation is to occur (131), the PDCP entity may perform a PDU set discard operation while discarding the PDU when the discardTimer of the PDU expires. On the other hand, in the case where the value of the importance level (ImportanceLevel) given for a specific PDU is less than or equal to the threshold of the importance level (132, 133, or 134) at which the PDU set discard operation is to occur, the PDCP entity may find it difficult to perform a PDU set discard operation while discarding the PDU when the discardTimer of the PDU expires.

[0073] Alternatively, in the case where the discardTimer of a specific PDU has expired, the PDCP entity may discard PDU 131, and may simultaneously perform a PDU set discard operation only for PDUs 132, 133, and 134, which have importance level values ​​equal to or less than PDU 131. On the other hand, a PDU having an importance level value higher than the PDU for which the discardTimer has expired may be exempted from the PDU set discard operation and thus may not be discarded.

[0074] In order to indicate the importance level of each PDU to the PDCP entity, the SDAP header may include an indicator (ImportanceLevel) indicating the importance level of the PDU. The indicator may be included in the SDAP headers of all PDUs constituting the PDU set. The SDAP layer may receive information about the importance level value of the PDU and information about the PDU set configuration from an upper layer (e.g., an application layer, an IP layer, or a non-access layer).

[0075] Figure 1f The PDU set discarding operation and configuration method according to an embodiment of the present disclosure are shown in the case where there is dependency between PDU sets.

[0076] refer to Figure 1f, in the case where there is a dependency between PDU sets, a PDU set discarding operation on a specific PDU set may result in a PDU set discarding operation on another PDU set that depends on the PDU set. In an embodiment, in the case of a video service, PDU sets 101 and 102 constituting B frames and / or P frames that are sent after the PDU set 100 constituting an I frame may depend on the PDU set 100 constituting the I frame. In other words, if a PDU set discarding operation occurs for the PDU set 100 constituting the I frame, so that the I frame cannot be recovered, the B frames and P frames that are sent thereafter may also not be recovered. Therefore, a PDU set discarding operation on the PDU set 100 constituting the I frame may result in a PDU set discarding operation on the PDU sets 101 and 102 constituting the B frames and / or P frames that are sent thereafter. That is, in the case where it is difficult to recover the I frame and it is difficult to recover the frame even if the PDU set constituting the B frames and P frames that are sent thereafter is received, the PDCP layer may discard the PDU set. In an embodiment, the PDU set 103 constituting the B frame may be dependent on the PDU set 104 constituting the I frame transmitted thereafter. Thereafter, a PDU set discard operation on the PDU set 104 constituting the I frame may result in a PDU set discard operation on the PDU set 103 constituting the B frame.

[0077] As in the above-mentioned embodiment, in the case where a PDU set discard operation has occurred on a specific PDU set, the dependency between PDU sets can be indicated to the PDCP layer, so that a PDU set discard operation is performed on a PDU set that depends on the PDU set. The dependency between PDU sets can be expressed in the following way:

[0078] Method 1: An indicator (e.g., DependencyIndex) may be given for each PDU set, the indicator including one or more indexes of PDU sets on which another PDU set depends. In the case where a PDU set discard operation has occurred for a specific PDU set 110, a PDU set discard operation may be performed for other PDU sets 113 and 115 whose index value (0) is included in DependencyIndex.

[0079] In order to indicate the dependencies between PDU sets to the PDCP entity, the SDAP header may include an index indicator (e.g., DependencyIndex) about another PDU set on which each PDU set depends, as well as PDU set index information. The indicator may be included in the SDAP headers of all PDUs constituting the PDU set, or may be included in the SDAP header of the first PDU constituting the PDU set. In the case where the indicator is included only in the SDAP header of the first PDU constituting the PDU set, the packet processing load on the SDAP / PDCP layer can be reduced. However, in the event of a problem in processing the first PDU of the PDU set, problems may also arise with respect to the configuration of the PDU set discard operation. The SDAP layer may receive information about dependencies between PDU sets, as well as information about the PDU set configuration, from an upper layer (e.g., an application layer, an IP layer, or a non-access layer).

[0080] Method 2: For each PDU set, a 1-bit indicator (e.g., DependencyBit, etc.) can be given to indicate whether the PDU set (PDU set index = n) depends on the previous PDU set (PDU set index = n-1). The indicator can indicate whether a specific PDU set depends on the previous PDU set in two types.

[0081] 1) Switching type: It may be indicated that if the dependency bit value of a specific PDU set 123 or 127 is equal to the dependency bit value of the previous PDU set 120 or 125, the PDU set 123 or 127 is dependent on the previous PDU set 120 or 125. Therefore, a PDU set discard operation on the previous PDU set 125 may result in a PDU set discard operation on the PDU set 127.

[0082] On the other hand, it may be indicated that if the dependency bit value of a particular PDU set 125 is different from the dependency bit value of a previous PDU set 123, the PDU set 125 is not dependent on the previous PDU set 123. A PDU set discard operation on the previous PDU set 123 may hardly cause a PDU set discard operation on the PDU set 125.

[0083] 2) True / false type: It can be indicated that if the dependency bit value of a specific PDU set 133 or 137 is "true" or "1", the PDU set 133 or 137 depends on the previous PDU set 130 or 135. Therefore, a PDU set discard operation on the previous PDU set 135 can result in a PDU set discard operation on the PDU set 137.

[0084] On the other hand, it can be indicated that if the dependency bit value of a specific PDU set 135 is "false" or "0", the PDU set 135 does not depend on the previous PDU set 133. Therefore, a PDU set discard operation on the previous PDU set 135 may hardly cause a PDU set discard operation on the PDU set 137.

[0085] Therefore, in the event that a PDU set discard operation has occurred for the PDU set 125 or 135 , the DependencyBit indicator value of the next PDU set 127 or 137 may determine whether a PDU set discard operation may occur for the PDU set 127 or 137 .

[0086] In order to indicate to the PDCP entity the dependency of a specific PDU set on a previous PDU set, the SDAP header may include an indicator (DependencyBit) and PDU set index information, which indicates whether a specific PDU set depends on a previous PDU set. The indicator may be included in the SDAP headers of all PDUs constituting the PDU set, or may be included in the SDAP header of the first PDU constituting the PDU set. In the case where the indicator is included only in the SDAP header of the first PDU constituting the PDU set, the packet processing load on the SDAP / PDCP layer can be reduced. However, in the event that a problem occurs when processing the first PDU of a PDU set, problems may also arise with respect to the configuration of the PDU set discard operation.

[0087] The SDAP layer may receive information about dependency on a previous PDU set and information about PDU set configuration from an upper layer (eg, an application layer, an IP layer, or a non-access layer).

[0088] Method 3: For each PDU set, an indicator (e.g., ImportanceLevel, etc.) may be given to indicate the importance level of the PDU set. For each PDU set, the indicator may indicate whether the PDU set (e.g., PDU set index = n) is dependent on the previous PDU set (e.g., PDU set index = n-1). If the ImportanceLevel value of a particular PDU set 143 or 147 is less than the ImportanceLevel value of the previous PDU set 140 or 145, the PDU set 143 or 147 may be considered to be dependent on the previous PDU set 140 or 145. Therefore, a PDU set discard operation on the previous PDU set 145 may result in a PDU set discard operation on the PDU set 147. On the other hand, if the ImportanceLevel value of a particular PDU set 145 is greater than the ImportanceLevel value of the previous PDU set 143, the PDU set 145 may be considered not to be dependent on the previous PDU set 143. Therefore, the PDU set discard operation on the previous PDU set 143 may hardly cause a PDU set discard operation on the PDU set 145 .

[0089] In order to indicate the importance level of each PDU set to the PDCP entity, the SDAP header may include an indicator (ImportanceLevel) indicating the importance level of the PDU set and the PDU set index information. The indicator may be included in the SDAP headers of all PDUs constituting the PDU set, or may be included in the SDAP header of the first PDU constituting the PDU set. In the case where only the SDAP header of the first PDU constituting the PDU set includes a PDU set importance level value, the packet processing load on the SDAP / PDCP layer can be reduced. However, in the event that a problem occurs when processing the first PDU of a PDU set, problems may also occur with respect to the configuration of the PDU set discard operation.

[0090] The SDAP layer may receive information about the PDU set importance level value and information about the PDU set configuration from an upper layer (eg, an application layer, an IP layer, or a non-access layer).

[0091] Figure 1g A signaling process between a UE and a base station according to an embodiment of the present disclosure is shown, which is used to configure a PDU set discard operation on the PDCP layer of the UE.

[0092] refer to Figure 1gIn step 110, the gNB 103 may deliver a UECapabilityEnquiry message to the UE 100 in the connected state to request a capability report. The gNB 103 may include a RAT type-specific UE capability query in the UECapabilityEnquiry message. The RAT type-specific query may include the requested frequency band information. In addition, in step 110, when the gNB 103 requests the UE 100 to generate a UECapabilityInformation message, filtering information that may indicate conditions and restrictions may be included therein. Through the filtering information, the gNB 103 may indicate whether the UE 100 must report capabilities related to the PDU set discard operation. In step 111, the UE 100 may write a UECapabilityInformation message corresponding to the UECapabilityEnquiry message in step 110, and may report a response to the UE capability query to the gNB 103. The UECapabilityInformation message may include a parameter indicating whether the UE 100 supports the PDU set discard operation. The gNB 103 may determine whether the UE 100 can perform the PDU set discard operation based on the UECapabilityInformation message received in step 111. In step 112, in the case where the gNB 103 has determined that the UE 100 can perform the PDU set discard operation, the gNB 103 may instruct the UE 100 to perform the PDU set discard operation when a specific condition is met through an RRCReconfiguration message. More specifically, in order to configure the PDU set discard operation, the RRCReconfiguration message may include the following configuration information:

[0093] discardTimer: The gNB 103 may configure a discardTimer value for the UE 100 for packet discard operations at the PDCP layer in delay-sensitive data transmission. The discardTimer value may have separate values ​​configured for: 1) each DRB; 2) each PDU type; and 3) each PDU set type.

[0094] discardTimer operation scheme: The operation scheme of discardTimer can be configured for PDCP discard operation. The configurable options include: 1) a scheme for operating discardTimer for each PDU set; and 2) a scheme for operating discardTimer for each PDCP SDU, and configuration information can be included to indicate at least one of these two options. The configuration information for indicating the discardTimer operation scheme can have separate values ​​configured for the following items: 1) each DRB; 2) each PDU type; and 3) each PDU set type.

[0095] PDU set discard operation configuration indicator: In order to configure the operation of PDU set discard, a 1-bit indicator such as "PDU_SetDiscardEnabled", "PDU_SetDiscard", "ADU_DiscardEnabled" or "ADU_Discard" may be delivered (or configured) to the UE 100 via an RRCReconfiguration message. In the case where the PDU set discard operation is configured for a specific DRB, the indicator may be configured in the PDCP-Config corresponding to the DRB.

[0096] In addition, the gNB 103 may configure the PDU set discard operation for each UE 100 instead of configuring the operation for each DRB. In the case where the operation is configured for each UE 100, the gNB 103 may transmit a 1-bit indicator (such as "PDU_SetDiscardEnabled", "PDU_SetDiscard", "ADU_DiscardEnabled" or "ADU-Discard") to the UE to configure the PDU set discard operation. The UE 100 may perform the PDU set discard operation for a DRB for which a discardTimer has been configured and for which configuration information about a PDU set (e.g., PDU set index information, etc.) has been received from an upper layer among all DRBs configured in the UE.

[0097] DRB ID list for PDU set discard: gNB 103 may pass a list of IDs of DRBs for which a PDU set discard operation is to be performed to UE 100, and UE 100 may perform the PDU set discard operation in the PDCP entity corresponding to the DRBs.

[0098] PDU set type for PDU set discard: In a case where whether to perform a PDU set discard operation for each PDU set differs according to the PDU set type, the gNB 103 may configure the PDU set (e.g., a PDU_SetType value list) on which the PDU set discard operation is to be performed for the UE 100 through an RRCReconfiguration message.

[0099] ADU discard threshold for PDU set: In a case where whether to perform a PDU set discard operation for each PDU set differs depending on the importance level of the PDU set, the gNB 103 may configure a threshold of the importance level of the PDU set (e.g., an ADU discard threshold) for the UE 100 through an RRCReconfiguration message, at which a discard operation of the PDU set is performed.

[0100] PDU type for PDU set discard: In the case where whether the expiration of the discardTimer of a PDU will cause a PDU set discard operation for the PDU set to which the PDU belongs varies according to the type of each PDU, the gNB 103 can configure the PDU types (e.g., a PDU_type value list) that can cause a PDU set discard operation for the UE 100 through an RRCReconfiguration message.

[0101] ADU discard threshold for PDU: In the case where whether the expiration of the discardTimer of a PDU will result in a PDU set discard operation for the PDU set to which the PDU belongs varies according to the importance level of each PDU, the gNB 103 may configure a threshold of the importance level of the PDU (e.g., an ADU discard threshold) for the UE 100 through an RRCReconfiguration message, at which the PDU set discard operation will occur.

[0102] Figure 2 A UE device according to an embodiment of the present disclosure is shown.

[0103] refer to Figure 2 , the UE may include a radio frequency (RF) processing unit 2-10, a baseband processing unit 2-20, a storage unit 2-30, and a controller 2-40. The components of the UE are not limited to Figure 2 The exemplary components shown in FIG. 1 and may include Figure 2 More components than shown in the Figure 2 Fewer components shown.

[0104] According to an embodiment of the present disclosure, the RF processing unit 2-10 can perform functions for sending / receiving signals through a wireless channel, such as signal band conversion and amplification. For example, the RF processing unit 2-10 can up-convert the baseband signal provided from the baseband processing unit 2-20 into an RF band signal, can transmit the signal through an antenna, and can down-convert the RF band signal received through the antenna into a baseband signal. For example, the RF processing unit 2-10 may include a transmitting filter, a receiving filter, an amplifier, a mixer, an oscillator, a digital-to-analog converter (DAC), an analog-to-digital converter (ADC), etc., but is not limited to these examples. Although Figure 2 Only one antenna is shown in the figure, but the UE may include multiple antennas. In addition, the RF processing unit 2-10 may include multiple RF chains. In addition, the RF processing unit 2-10 can perform beamforming. For beamforming, the RF processing unit 2-10 can adjust the phase and amplitude of the signal sent / received through multiple antennas or antenna elements, respectively. In addition, the RF processing unit 2-10 can perform MIMO and can receive multiple layers when performing multiple-input multiple-output (MIMO) operations.

[0105] The baseband processing unit 2-20 can perform the conversion function between the baseband signal and the bit string according to the physical layer specification of the system. For example, during data transmission, the baseband processing unit 2-20 can encode and modulate the transmitted bit string to generate complex symbols. In addition, during data reception, the baseband processing unit 2-20 can demodulate and decode the baseband signal provided from the RF processing unit 2-10 to recover the received bit string. For example, when following the OFDM scheme, during data transmission, the baseband processing unit 2-20 can encode and modulate the transmitted bit string to generate complex symbols, and the complex symbols can be mapped to subcarriers, and OFDM symbols can be configured by inverse fast Fourier transform (IFFT) operation and cyclic prefix (CP) insertion. In addition, during data reception, the baseband processing unit 2-20 can divide the baseband signal provided from the RF processing unit 2-10 into OFDM symbols, and the signal mapped to the subcarrier can be recovered by fast Fourier transform (FFT) operation, and the received bit string can be recovered by demodulation and decoding.

[0106] According to an embodiment of the present disclosure, the baseband processing unit 2-20 and the RF processing unit 2-10 may transmit and receive signals as described above. Therefore, the baseband processing unit 2-20 and the RF processing unit 2-10 may be referred to as a transmitter, a receiver, a transceiver, or a communication unit. In addition, at least one of the baseband processing unit 2-20 and the RF processing unit 2-10 may include multiple communication modules to support a variety of different wireless access technologies. In addition, at least one of the baseband processing unit 2-20 and the RF processing unit 2-10 may include different communication modules to process signals of different frequency bands. For example, different wireless access technologies may include wireless LAN (e.g., IEEE 802.11), cellular networks (e.g., LTE), etc. In addition, different frequency bands may include super high frequency (SHF) (e.g., 2.NRHz, NRHz) bands and millimeter wave (e.g., 60GHz) bands. The UE may transmit / receive signals with the gNB by using the baseband processing unit 2-20 and the RF processing unit 2-10, and the signals may include control information and data.

[0107] According to an embodiment of the present disclosure, the storage unit 2-30 may store data, such as basic programs, applications, and configuration information for the operation of the UE. For example, the storage unit 2-30 may store data information, such as basic programs, applications, and configuration information for the operation of the UE. In addition, the storage unit 2-30 may provide the stored data at the request of the controller 2-40.

[0108] The storage unit 2-30 may be configured by a storage medium such as a ROM, a RAM, a hard disk, a CD-ROM, and a DVD, or a combination of storage media. In addition, the storage unit 2-30 may be configured by a plurality of memories.

[0109] The controller 2-40 can control the overall operation of the UE. For example, the controller 2-40 can send / receive signals through the baseband processing unit 2-20 and the RF processing unit 2-10. In addition, the controller 2-40 can record and read data in the storage unit 2-30. To this end, the controller 2-40 may include at least one processor. For example, the controller 2-40 may include a communication processor (CP) configured to perform communication control and an application processor (AP) configured to control an upper layer (such as an application). In addition, according to an embodiment of the present disclosure, the controller 2-40 may include a multi-connection processing unit 2-42 configured to process a process running in a multi-connection mode. In addition, at least one component in the UE may be implemented as a chip.

[0110] Figure 3 A gNB device according to an embodiment of the present disclosure is shown.

[0111] refer to Figure 3, the gNB may include an RF processing unit 3-10, a baseband processing unit 3-20, a backhaul communication unit 3-30, a storage unit 3-40, and a controller 3-50. The components of the gNB are not limited to Figure 3 The exemplary components shown in FIG. 1 and FIG. 2 may include: Figure 3 More components than shown may also be included Figure 3 Fewer components shown.

[0112] According to an embodiment of the present disclosure, the RF processing unit 3-10 can perform functions for sending / receiving signals through a wireless channel, such as signal band conversion and amplification. That is, the RF processing unit 3-10 can up-convert the baseband signal provided from the baseband processing unit 3-20 into an RF band signal, can transmit the signal through an antenna, and can down-convert the RF band signal received through the antenna into a baseband signal. For example, the RF processing unit 3-10 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a DAC, and an ADC. Although in Figure 3 Only one antenna is shown in the figure, but the RF processing unit 3-10 may include multiple antennas. In addition, the RF processing unit 3-10 may include multiple RF chains. In addition, the RF processing unit 3-10 may perform beamforming. For beamforming, the RF processing unit 3-10 may adjust the phase and amplitude of the signal sent / received through multiple antennas or antenna elements, respectively. The RF processing unit 3-10 may send one or more layers to perform downward MIMO operation.

[0113] According to an embodiment of the present disclosure, the baseband processing unit 3-20 can perform a conversion function between a baseband signal and a bit string according to a physical layer specification. For example, during data transmission, the baseband processing unit 3-20 can encode and modulate the transmitted bit string to generate a complex symbol. In addition, during data reception, the baseband processing unit 3-20 can demodulate and decode the baseband signal provided from the RF processing unit 3-10 to recover the received bit string. For example, when following the OFDM scheme, during data transmission, the baseband processing unit 3-20 can encode and modulate the transmitted bit string to generate a complex symbol, the complex symbol can be mapped to a subcarrier, and the OFDM symbol can be configured by IFFT operation and CP insertion. In addition, during data reception, the baseband processing unit 3-20 can divide the baseband signal provided from the RF processing unit 3-10 into OFDM symbols, the signal mapped to the subcarrier can be recovered by FFT operation, and the received bit string can be recovered by demodulation and decoding. The baseband processing unit 3-20 and the RF processing unit 3-10 can transmit and receive signals as described above. Therefore, the baseband processing unit 3-20 and the RF processing unit 3-10 can be called a transmitter, a receiver, a transceiver, a communication unit, or a wireless communication unit. The gNB can transmit / receive signals with the UE by using the baseband processing unit 3-20 and the RF processing unit 3-10, and the signals may include control information and data.

[0114] According to an embodiment of the present disclosure, the backhaul communication unit 3-30 may provide an interface for communicating with other nodes in the network. For example, the backhaul communication unit 3-30 may convert a bit string sent from the master gNB to other nodes (e.g., secondary gNB, core network) into a physical signal, and may convert a physical signal received from other nodes into a bit string.

[0115] According to an embodiment of the present disclosure, the storage unit 3-40 may store data such as basic programs, applications, and configuration information for the operation of the master gNB. For example, the storage unit 3-40 may store information about the bearers assigned to the connected UE, measurement results reported from the connected UE, and the like. In addition, the storage unit 3-40 may store information used as a reference to determine whether to provide multiple connections to the UE or to suspend the multiple connections. In addition, the storage unit 3-40 may provide the stored data at the request of the controller 3-50. The storage unit 3-40 may be configured by a storage medium such as a ROM, a RAM, a hard disk, a CD-ROM, and a DVD, or a combination of storage media. In addition, the storage unit 3-40 may be configured by a plurality of memories.

[0116] According to an embodiment of the present disclosure, the controller 3-50 may control the overall operation of the master gNB. For example, the controller 3-50 may send / receive signals through the baseband processing unit 3-20 and the RF processing unit 3-10 or through the backhaul communication unit 3-30. In addition, the controller 3-50 may record and read data in the storage unit 3-40. To this end, the controller 3-50 may include at least one processor. In addition, according to an embodiment of the present disclosure, the controller 3-50 may include a multi-connection processing unit 3-52 configured to process a process running in a multi-connection mode.

[0117] The methods disclosed in the claims and / or the methods according to the embodiments described in the specification of the present disclosure may be implemented by hardware, software, or a combination of hardware and software.

[0118] When these methods are implemented by software, a computer-readable storage medium for storing one or more programs (software modules) may be provided. One or more programs stored in the computer-readable storage medium may be configured to be executed by one or more processors in the electronic device. At least one program includes instructions for causing the electronic device to perform the methods according to the various embodiments of the present disclosure as defined by the appended claims and / or disclosed herein.

[0119] These programs (software modules or software) can be stored in non-volatile memory, including random access memory and flash memory, read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), magnetic disk storage device, compact disk ROM (CD-ROM), digital versatile disk (DVD) or other types of optical storage devices, or magnetic tape. Or, any combination of some or all of them can form a memory for storing programs. In addition, multiple such memories can be included in the electronic device.

[0120] In addition, the program can be stored in an attachable storage device that can access the electronic device through a communication network such as the Internet, an intranet, a local area network (LAN), a wide area network (WLAN), and a storage area network (SAN), or a combination thereof. Such a storage device can access the electronic device through an external port. In addition, a separate storage device on a communication network can access the portable electronic device.

[0121] In the present disclosure, the term "computer program product" or "computer-readable medium" generally refers to a medium such as a memory, a hard disk installed in a hard disk drive, or a signal. The "computer program product" or "computer-readable medium" is an element provided to the method for reporting UE capabilities in a wireless communication system according to the present disclosure.

[0122] The machine-readable storage medium may be provided in the form of a non-transitory storage medium. Here, the term "non-transitory" simply means that the storage medium is a tangible device and does not include signals (e.g., electromagnetic waves), but the term does not distinguish between where data is semi-permanently stored in the storage medium and where data is temporarily stored in the storage medium. For example, a "non-transitory storage medium" may include a buffer that temporarily stores data.

[0123] According to an embodiment, the method according to various embodiments of the present disclosure may be included and provided in a computer program product. The computer program product may be traded between a seller and a buyer as a product. The computer program product may be released in the form of a machine-readable storage medium (e.g., a compact disk read-only memory (CD-ROM)), or may be downloaded via an application store (e.g., Play Store TM ) the computer program product may be published online (e.g., downloaded or uploaded) or the computer program product may be distributed directly between two user devices (e.g., smart phones). If published online, at least part of the computer program product may be temporarily generated or at least part of the computer program product may be at least temporarily stored in a machine-readable storage medium (such as a memory of a manufacturer's server, an application store's server, or a relay server).

[0124] In the above detailed embodiments of the present disclosure, the elements included in the present disclosure are expressed in the singular or plural, depending on the detailed embodiments presented. However, for ease of description, the singular form or plural form is appropriately selected for the presented situation, and the present disclosure is not limited to the elements expressed in the singular or plural. Therefore, the elements expressed in the plural may also include a single element, or the elements expressed in the singular may also include multiple elements.

[0125] The embodiments of the present disclosure described and shown in the specification and the drawings are merely specific examples proposed to easily explain the technical content of the present disclosure and help understand the present disclosure, and are not intended to limit the scope of the present disclosure. That is, it will be understood by those skilled in the art that other variants of the technical ideas based on the present disclosure can be implemented. In addition, the above-mentioned various embodiments can be used in combination as needed. For example, a part of an embodiment of the present disclosure can be combined with a part of another embodiment to operate a base station and a terminal. In addition, the embodiments of the present disclosure can be applied to other communication systems, and other variants of the technical ideas based on the embodiments can also be implemented. For example, the embodiments can be applied to LTE, 5G, NR or 6G systems. Therefore, the scope of the present disclosure should not be defined as being limited to the embodiments described herein, but should be defined by the attached claims and their equivalents.

Claims

1. A method performed by a terminal in a wireless communication system, the method comprising: receiving a terminal capability query message from a base station; In response to the terminal capability query message, sending terminal capability information including information related to discarded protocol data unit (PDU) sets to the base station; as well as In a case where the terminal supports discarding the PDU set, receiving configuration information on discarding the PDU set from the base station, Wherein, in a case where at least one PDU constituting the PDU set needs to be discarded, the PDU set is discarded based on the configuration information.

2. The method according to claim 1, wherein: The configuration information includes at least one of the following: a timer for determining whether to discard the at least one PDU, a discard indicator, a data radio bearer DRB identifier, a type of the PDU set, or a threshold value regarding an importance level of the PDU set.

3. The method according to claim 2, wherein: The importance level is identified for each PDU set, and whether to discard the PDU set is determined based on the importance level and the threshold.

4. The method according to claim 2, wherein: The threshold is configured for each DRB or terminal, and the configuration unit and size of the threshold are determined according to the service type.

5. A method performed by a base station in a wireless communication system, the method comprising: Sending a terminal capability query message to the terminal; In response to the terminal capability query message, receiving terminal capability information including information related to discarding a protocol data unit (PDU) set from the terminal; as well as In a case where the terminal supports discarding the PDU set, sending configuration information about discarding the PDU set to the terminal, Wherein, in a case where at least one PDU constituting the PDU set needs to be discarded, the PDU set is discarded based on the configuration information.

6. The method according to claim 5, wherein: The configuration information includes at least one of the following: a timer for determining whether to discard the at least one PDU, a discard indicator, a data radio bearer DRB identifier, a type of the PDU set, or a threshold value regarding an importance level of the PDU set.

7. The method according to claim 6, wherein: The importance level is identified for each PDU set, and whether to discard the PDU set is determined based on the importance level and the threshold.

8. The method according to claim 6, wherein: The threshold is configured for each DRB or terminal, and the configuration unit and size of the threshold are determined according to the service type.

9. A terminal in a wireless communication system, the terminal comprising: Transceiver; as well as at least one processor coupled to the transceiver and configured to: receiving a terminal capability query message from a base station; In response to the terminal capability query message, sending terminal capability information including information related to discarded protocol data unit (PDU) sets to the base station; as well as In a case where the terminal supports discarding the PDU set, receiving configuration information on discarding the PDU set from the base station, Wherein, in a case where at least one PDU constituting the PDU set needs to be discarded, the PDU set is discarded based on the configuration information.

10. The terminal according to claim 9, wherein: The configuration information includes at least one of the following: a timer for determining whether to discard the at least one PDU, a discard indicator, a data radio bearer DRB identifier, a type of the PDU set, or a threshold value regarding an importance level of the PDU set. The terminal according to claim 10 , wherein: The importance level is identified for each PDU set, and whether to discard the PDU set is determined based on the importance level and the threshold.

12. The terminal according to claim 10, wherein: The threshold is configured for each DRB or terminal, and the configuration unit and size of the threshold are determined according to the service type.

13. A base station in a wireless communication system, the base station comprising: Transceiver; as well as at least one processor coupled to the transceiver and configured to: Sending a terminal capability query message to the terminal; In response to the terminal capability query message, receiving terminal capability information including information related to discarding a protocol data unit (PDU) set from the terminal; as well as In a case where the terminal supports discarding the PDU set, sending configuration information about discarding the PDU set to the terminal, Wherein, in a case where at least one PDU constituting the PDU set needs to be discarded, the PDU set is discarded based on the configuration information.

14. The base station according to claim 13, wherein: The configuration information includes at least one of the following: a timer for determining whether to discard the at least one PDU, a discard indicator, a data radio bearer DRB identifier, a type of the PDU set, or a threshold value regarding an importance level of the PDU set.

15. The base station according to claim 14, wherein: The importance level is identified for each PDU set, and whether to discard the PDU set is determined based on the importance level and the threshold.

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