KR20240147397A - Method and apparatus for NW indication-based packet discard in wireless communication systems - Google Patents

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting higher data rates.

Description

Method and apparatus for NW indication-based packet discard in wireless communication systems

The present disclosure relates to operations of a terminal and a base station in a wireless communication system, and more particularly, to a method and device for a terminal to discard an uplink transmission packet according to a network instruction.

5G mobile communication technology defines a wide frequency band to enable fast transmission speeds and new services, and can be implemented not only in the sub-6GHz frequency band, such as 3.5 gigahertz (3.5GHz), but also in the ultra-high frequency band called millimeter wave (㎜Wave), such as 28GHz and 39GHz ('Above 6GHz'). In addition, for 6G mobile communication technology, which is called the system after 5G communication (Beyond 5G), implementation in the terahertz band (for example, the 3 terahertz (3THz) band at 95GHz) is being considered to achieve a transmission speed that is 50 times faster than 5G mobile communication technology and an ultra-low delay time that is reduced by one-tenth.

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

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

In addition, standardization of wireless interface architecture/protocols for technologies such as the Industrial Internet of Things (IIoT) to support new services through linkage and convergence with other industries, Integrated Access and Backhaul (IAB) to provide 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 RACH for NR to simplify random access procedures is also in progress, and standardization of system architecture/services for 5G baseline architecture (e.g. Service based Architecture, Service based Interface) for grafting Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and Mobile Edge Computing (MEC) that provides services based on the location of the terminal is also in progress.

When such 5G mobile communication systems are commercialized, an explosive increase in connected devices will be connected to the communication network, which will require enhanced functions and performance of 5G mobile communication systems and integrated operation of connected devices. To this end, new research will be conducted on improving 5G performance and reducing complexity using eXtended Reality (XR), Artificial Intelligence (AI), and Machine Learning (ML) to efficiently support Augmented Reality (AR), Virtual Reality (VR), and Mixed Reality (MR), AI service support, metaverse service support, and drone communications.

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

The disclosed embodiment seeks to provide a device and method capable of effectively providing XR services in a wireless communication system.

The present disclosure for solving the above problems is characterized by a method for processing a control signal in a communication system, comprising: a step of receiving a first control signal transmitted from a base station; a step of processing the received first control signal; and a step of transmitting a second control signal generated based on the processing to the base station.

The present disclosure provides a device and method capable of effectively providing XR service in a wireless communication system.

FIG. 1a illustrates the structure of a next-generation mobile communication system according to one embodiment of the present disclosure.
FIG. 1b illustrates a wireless protocol architecture in a long term evolution (LTE) and new radio (NR) system according to one embodiment of the present disclosure.
FIG. 1c illustrates a configuration of an application data unit (ADU) unit protocol data unit (PDU) set according to one embodiment of the present disclosure.
FIG. 1d illustrates an operation and procedure for a terminal to discard an uplink transmission packet based on PDU set importance according to a network instruction according to one embodiment of the present disclosure.
FIG. 1e illustrates various operation methods and procedures for a terminal to discard uplink transmission packets based on PDU set importance according to a network instruction according to one embodiment of the present disclosure.
FIG. 1f illustrates an operation and procedure for a terminal to discard PDCP SDUs based on PDU set importance for a specific time period according to a network instruction according to an embodiment of the present disclosure.
FIG. 1g illustrates an operation and procedure for a terminal to use a separate discarding timer value per PDU set importance unit according to a network instruction according to one embodiment of the present disclosure.
FIG. 1h illustrates an operation and procedure for changing a PDCP discarding timer value used in a PDCP layer for each DRB unit of a terminal according to a network instruction according to one embodiment of the present disclosure.
FIG. 1i illustrates a procedure for a terminal to report information about uplink packets waiting for transmission to a base station to help indicate PDCP discarding operation based on PDU set importance of a network according to one embodiment of the present disclosure.
FIG. 1j illustrates a PDU set discarding operation method in a PDCP layer according to one embodiment of the present disclosure.
FIG. 2 illustrates a terminal device according to one embodiment of the present disclosure.
FIG. 3 illustrates a base station device according to one embodiment of the present disclosure.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the attached drawings. In addition, when describing the present disclosure, if it is determined that a specific description of a related known function or configuration may unnecessarily obscure the gist of the present disclosure, the detailed description thereof will be omitted. In addition, the terms described below are terms defined in consideration of the functions in the present disclosure, and these may vary depending on the intention or custom of the user or operator. Therefore, the definitions should be made based on the contents throughout this specification. Hereinafter, embodiments of the present invention will be described with reference to the attached drawings.

The advantages and features of the present disclosure, and the methods for achieving them, will become apparent by referring to the embodiments described in detail below together with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below and may be implemented in various different forms, and the embodiments are provided only to make the disclosure of the present disclosure complete and to fully inform those skilled in the art of the scope of the invention, and the present disclosure is defined only by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

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

Additionally, each block may represent a module, segment, or portion of code that contains one or more executable instructions for performing a particular logical function(s). It should also be noted that in some alternative implementation examples, the functions mentioned in the blocks may occur out of order. For example, two blocks shown in succession may in fact be performed substantially concurrently, or the blocks may sometimes be performed in reverse order, depending on the functionality they perform.

Here, the term '~ part' used in this embodiment means software or hardware components such as FPGA (Field Programmable Gate Array) or ASIC (Application Specific Integrated Circuit), and the '~ part' performs certain roles. However, the '~ part' is not limited to software or hardware. The '~ part' may be configured to be in an addressable storage medium and may be configured to reproduce 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, and processes, functions, properties, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functions provided in 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 regenerate one or more CPUs within the device or secure multimedia card. Also, in an embodiment, the '~part' may include one or more processors.

In the following description of the present disclosure, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the gist of the present disclosure, the detailed description thereof will be omitted. Hereinafter, an embodiment of the present disclosure will be described with reference to the attached drawings.

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

In the following description, the terms physical channel and signal may be used interchangeably with data or control signals. For example, PDSCH (physical downlink shared channel) is a term referring 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 'transmitting a physical channel' may be interpreted equivalently to the expression 'transmitting data or a signal through a physical channel'.

In the present disclosure below, upper signaling means a signal transmission method in which a base station transmits a signal to a terminal using a downlink data channel of a physical layer, or a terminal transmits a signal to a base station using an uplink data channel of a physical layer. Upper signaling can be understood as RRC (radio resource control) signaling or MAC (media access control) control element (CE).

For convenience of explanation below, this disclosure uses terms and names defined in the 3rd Generation Partnership Project NR (New Radio) or 3rd Generation Partnership Project Long Term Evolution (LTE) standards. However, this disclosure is not limited by the above terms and names, and can be equally applied to systems conforming to other standards. In this disclosure, gNB may be used interchangeably with eNB for convenience of explanation. That is, a base station described as an eNB may represent a gNB. In addition, the term terminal may represent a mobile phone, an MTC device, an NB-IoT device, a sensor, as well as other wireless communication devices.

Hereinafter, the base station is an entity that performs resource allocation of a terminal, and may be at least one of a gNodeB (gNB), an eNode B (eNB), a NodeB, a BS (Base Station), a wireless access unit, a base station controller, or a node on a network. The terminal may include a UE (User Equipment), an MS (Mobile Station), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing a communication function. Of course, it is not limited to the above examples.

In particular, the present disclosure can be applied to 3GPP NR (5th generation mobile communication standard). In addition, the present disclosure can be applied to intelligent services (e.g., smart home, smart building, smart city, smart car or connected car, healthcare, digital education, retail, security and safety related services, etc.) based on 5G communication technology and IoT related technology. In the present disclosure, eNB may be used interchangeably with gNB for convenience of explanation. That is, a base station described as eNB may represent gNB. In addition, the term terminal may represent not only mobile phones, NB-IoT devices, and sensors, but also other wireless communication devices.

Wireless communication systems are evolving from providing initial voice-oriented services to broadband wireless communication systems that provide high-speed, high-quality packet data services, such as communication standards such as 3GPP's HSPA (High Speed Packet Access), LTE (Long Term Evolution or E-UTRA (Evolved Universal Terrestrial Radio Access), LTE-Advanced (LTE-A), LTE-Pro, 3GPP2's HRPD (High Rate Packet Data), UMB (Ultra Mobile Broadband), and IEEE's 802.16e.

As a representative example of a broadband wireless communication system, the LTE system adopts the OFDM (Orthogonal Frequency Division Multiplexing) method in the downlink (DL) and the SC-FDMA (Single Carrier Frequency Division Multiple Access) method in the uplink (UL). The uplink refers to a wireless link in which a terminal (UE; User Equipment or MS; Mobile Station) transmits data or a control signal to a base station (eNode B or BS; Base Station), and the downlink refers to a wireless link in which a base station transmits data or a control signal to a terminal. The above multiple access method distinguishes the data or control information of each user by allocating and operating the time-frequency resources to be transmitted to each user so that they do not overlap, that is, so as to establish orthogonality.

As a future communication system after LTE, that is, a 5G communication system must be able to freely reflect various requirements of users and service providers, and therefore services that simultaneously satisfy various requirements must be supported. Services being considered for the 5G communication system include enhanced mobile broadband (eMBB), massive machine type communication (mMTC), and ultra-reliable low latency communication (URLLC).

In some embodiments, eMBB may aim to provide a data transmission rate that is higher than that supported by existing LTE, LTE-A or LTE-Pro. For example, in a 5G communication system, eMBB should be able to provide a peak data rate of 20 Gbps in the downlink and a peak data rate of 10 Gbps in the uplink from the perspective of a single base station. In addition, the 5G communication system may need to provide an increased user perceived data rate while providing the peak data rate. To satisfy such requirements, the 5G communication system may require improvements in various transmission and reception technologies, including further enhanced multi-antenna (MIMO; Multi Input Multi Output) transmission technology. In addition, while the current LTE transmits signals using a maximum transmission bandwidth of 20 MHz in the 2 GHz band, the 5G communication system may use a wider frequency bandwidth than 20 MHz in a frequency band of 3 to 6 GHz or higher, thereby satisfying the data transmission rate required by the 5G communication system.

At the same time, mMTC is being considered to support application services such as the Internet of Things (IoT) in 5G communication systems. In order to efficiently provide the Internet of Things, mMTC may require support for large-scale terminal connection within a cell, improved terminal coverage, improved battery life, and reduced terminal costs. Since the Internet of Things provides communication functions by attaching various sensors and various devices, it must be able to support a large number of terminals (e.g., 1,000,000 terminals/km2) within a cell. In addition, terminals supporting mMTC are likely to be located in shadow areas that cells do not cover, such as basements of buildings, due to the nature of the service, and therefore, wider coverage may be required compared to other services provided by 5G communication systems. Terminals supporting mMTC must be composed of low-cost terminals, and since it is difficult to frequently replace the terminal batteries, a very long battery life time, such as 10 to 15 years, may be required.

Finally, URLLC is a cellular-based wireless communication service used for specific purposes (mission-critical), such as remote control of robots or machinery, industrial automation, unmanned aerial vehicles (UAVs), remote health care, emergency alert, etc. Therefore, the communication provided by URLLC may need to provide very low latency (ultra-low latency) and very high reliability (ultra-reliability). For example, a service supporting URLLC may need to satisfy an air interface latency of less than 0.5 milliseconds, and may also have a requirement of a packet error rate (PER) of less than 10-5. Therefore, for services supporting URLLC, 5G systems may be required to provide a smaller Transmit Time Interval (TTI) than other services, while simultaneously allocating wide resources in the frequency band to ensure the reliability of the communication link.

The three services considered in the aforementioned 5G communication system, namely eMBB, URLLC, and mMTC, can be multiplexed and transmitted in one system. At this time, different transmission/reception techniques and transmission/reception parameters can be used between the services in order to satisfy different requirements of each service. However, the aforementioned mMTC, URLLC, and eMBB are only examples of different service types, and the service types to which the present disclosure is applied are not limited to the aforementioned examples.

In addition, although the embodiments of the present disclosure are described below using LTE, LTE-A, LTE Pro or 5G (or NR, next-generation mobile communication) systems as examples, the embodiments of the present disclosure may be applied to other communication systems having similar technical backgrounds or channel types. In addition, the embodiments of the present disclosure may be applied to other communication systems through some modifications without significantly departing from the scope of the present disclosure as judged by a person having skilled technical knowledge.

Referring to FIG. 1a, a wireless access network of a wireless communication system (hereinafter, a next-generation mobile communication system (New Radio, NR or 5G)) as illustrated is composed of a next-generation base station (New Radio Node B, hereinafter, gNB) (1a-10) and an AMF (1a-05, New Radio Core Network). A user terminal (New Radio User Equipment, hereinafter, NR UE or terminal) (1a-15) accesses an external network through the gNB (1a-10) and the AMF (1a-05).

In Fig. 1a, the gNB (1a-10) may correspond to an eNB (Evolved Node B) (1a-30) of an existing LTE system. The gNB (1a-10) is connected to an NR UE (1a-15) via a wireless channel and may provide a service superior to that of an existing Node B (1a-20).

According to one embodiment of the present disclosure, in a next-generation mobile communication system, since all user traffic is serviced through a shared channel, a device that collects status information such as buffer status, available transmission power status, and channel status of UEs and performs scheduling is required, and this is handled by a gNB (1a-10). One gNB can typically control multiple cells.

According to one embodiment of the present disclosure, in order to implement ultra-high-speed data transmission compared to existing LTE, it may have a bandwidth greater than the existing maximum bandwidth, and an orthogonal frequency division multiplexing (hereinafter referred to as OFDM) method may be used as a wireless access technology, and additionally beamforming technology may be used.

In addition, according to one embodiment of the present disclosure, an adaptive modulation & coding (AMC) method that determines a modulation scheme and a channel coding rate according to a channel condition of a terminal can be applied. AMF (1a-05) can perform functions such as mobility support, bearer setup, and QoS setup. AMF is a device that is in charge of various control functions as well as mobility management functions for the terminal and can be connected to a plurality of base stations. In addition, the next-generation mobile communication system can also be interlinked with the existing LTE system, and AMF (1a-05) is connected to MME (1a-25) through a network interface. MME (1a-25) is connected to eNB (1a-30), which is an existing base station. A terminal supporting LTE-NR Dual Connectivity can transmit and receive data while maintaining a connection to not only gNB (1a-10) but also eNB (1a-30) (1a-35).

FIG. 1b illustrates a wireless protocol architecture in an LTE and NR system according to one embodiment of the present disclosure.

Referring to FIG. 1b, the wireless protocol of the NR system may be composed of SDAP (service data adaptation protocol) (1b-05)(1b-10), PDCP (packet data convergence protocol) (1b-15)(1b-20), radio link control (RLC) (1b-25)(1b-30), and MAC (medium access control) (1b-35)(1b-40) in the terminal and the gNB, respectively. SDAP (1b-05)(1b-10) may perform an operation to map each QoS flow to a specific DRB (data radio bearer), and the SDAP configuration corresponding to each DRB may be provided from a higher layer (e.g., RRC layer).

According to one embodiment of the present disclosure, PDCP (1b-15)(1b-20) may be responsible for operations such as IP header compression and/or restoration, and may perform a re-ordering operation on data packets to provide an in-order delivery service to a higher layer. In addition, RLC (1b-25)(1b-30) may reconfigure PDCP PDUs into an appropriate size. MAC (1b-35)(1b-40) may be connected to a plurality of RLC layer devices configured in one terminal, and may perform operations of multiplexing RLC PDUs into MAC PDUs and demultiplexing RLC PDUs from MAC PDUs. The physical (PHY) layer (1b-45)(1b-50) can perform operations of channel coding and modulating upper layer data, creating OFDM (orthogonal frequency-division multiplexing) symbols and transmitting them through a wireless channel, or demodulating OFDM symbols received through a wireless channel and channel decoding them and transmitting them to a higher layer.

In addition, according to one embodiment of the present disclosure, the PHY layer (1b-45)(1b-50) can use HARQ (hybrid automatic repeat request) for additional error correction, and the receiver can transmit whether a packet transmitted by the transmitter has been received with 1 bit. Information on whether the receiver has received a packet received from the transmitter can be referred to as HARQ ACK/NACK information. In the case of an LTE system, downlink HARQ ACK/NACK information for uplink data transmission can be transmitted through a physical hybrid-arq indicator channel (PHICH). In the case of an NR system, downlink HARQ ACK/NACK information for uplink data transmission can be transmitted through a physical dedicated control channel (PDCCH), which is a channel through which downlink and/or uplink resource allocation, etc. are transmitted, and the base station can determine whether retransmission is necessary or whether new transmission can be performed through scheduling information of a terminal.

Unlike LTE, the reason why the base station in the NR system determines whether retransmission is necessary or a new transmission can be performed through the scheduling information of the terminal may be because NR applies asynchronous HARQ. Uplink HARQ ACK/NACK information for downlink data transmission can be transmitted through the physical uplink control channel (PUCCH) or the physical uplink shared channel (PUSCH). PUCCH can generally be transmitted in the uplink of the PCell (primary cell), which will be described later. However, if the terminal supports it, HARQ ACK/NACK information for the SCell (secondary cell), which will be described later, can be transmitted, and in this case, the SCell can be referred to as a PUCCH SCell.

Although not shown in this drawing, an RRC (radio resource control) layer may exist above the PDCP layer of each terminal and base station, and the RRC layer can exchange connection and measurement-related setting control messages for radio resource control.

Meanwhile, the PHY layer (1b-45)(1b-50) may be composed of one or more frequencies and/or carriers, and a technology that sets and uses multiple frequencies simultaneously may be referred to as carrier aggregation (CA). CA technology refers to a technology that uses a primary carrier and one or more secondary carriers in addition to a single carrier for communication between a terminal and a base station (e.g., eNB or gNB), and by using CA technology, the transmission amount can be increased by the number of secondary carriers. Meanwhile, in LTE and NR systems, a cell within a base station that uses a primary carrier may be referred to as a primary cell or PCell, and a cell within a base station that uses a secondary carrier may be referred to as a secondary cell or SCell.

FIG. 1c illustrates an application data unit (ADU) unit PDU set configuration according to one embodiment of the present disclosure.

Referring to FIG. 1c, various types of traffic can be classified into ADUs, which are units of information that can be classified at the application level. According to one embodiment, an ADU can be a single photo or picture, a single frame of video data, or a single unit of audio data. An ADU can be classified into PDU set (1c-10) units, and a PDU set (1c-10) can be divided into at least one PDU (1c-01, 1c-02, 1c-03, 1c-04, 1c-05, 1c-06) according to its size and transmitted.

For example, when the MPEG (moving picture experts group) standard video compression technology is used in video traffic, a PDU set may be composed of at least one of 1) a combination of multiple PDUs corresponding to one I (intra)-frame (1c-30), 2) a combination of multiple PDUs corresponding to one B (bidirectional)-frame (1c-40), and 3) a combination of multiple PDUs corresponding to one P (predicted)-frame (1c-50).

According to one embodiment of the present disclosure, an I-frame (1c-20) is an independent frame and can represent a single complete photograph or picture (1c-21) regardless of the presence or absence of other frames. A P-frame and a B-frame (1c-22) are frames that represent change information of a previous I-frame (1c-20). If the I-frame (1c-20) is not received normally, it may be difficult to normally represent a photograph or picture (1c-23) that was intended to be expressed by the P-frame and B-frame (1c-22). In addition, in the case of a B-frame, since it is stored as data that infers a movement between the two frames by referencing both frames between the I-frame and the P-frame, not only the I-frame in front but also the P-frame behind must be received normally in order for a photograph or picture that was intended to be expressed by the B-frame to be normally represented.

In the embodiment of the present disclosure, for the sake of ease of explanation, the configuration of a PDU set may be described by taking as an example a case where MPEG standard video compression technology is used in video traffic. However, the contents of the present disclosure are not limited to the configuration of a PDU set in video traffic, and may be applied to all PDU set configurations composed of general ADU units.

According to an embodiment of the present disclosure, an XR traffic flow for a specific XR (extended reality) service may be composed of a combination of data (e.g., PDUs, PDU sets, etc.) having different quality of service (QoS) requirements. For example, when video traffic coded in MPEG is transmitted for a specific XR service, several types of PDU sets having different QoS requirements (e.g., delay, reliability, etc.) corresponding to I-frame/B-frame/P-frame may compose a single XR traffic flow.

According to one embodiment of the present disclosure, in order to service an XR traffic flow composed of data having various QoS requirements, a network can map the XR traffic flow to one or more QoS flows. As described above, when one or more QoS flows are used to service a specific XR traffic flow, data constituting the same XR traffic flow can be transmitted through different QoS flows according to the QoS requirements. At this time, the different QoS flows can be mapped to different DRBs or can be mapped to the same DRB. In addition, PDU sets transmitted through the same QoS flow can have different priorities. For example, in the case of the video traffic, a PDU set corresponding to an I-frame can have a relatively higher priority than a PDU set corresponding to a B-frame or a P-frame. The importance of each PDU set can be expressed as a number from 0 to 8, or {True, false} or {0, 1}, and in the case of downlink data, the UPF can include the importance information in the GTP-U header, and the base station can consider the importance when transmitting the PDU set through the downlink. In addition, in the case of the uplink, the importance information can be transmitted from the application layer of the terminal to a lower layer (e.g., SDAP, PDCP, RLC, MAC) through the terminal internal interface, or the importance information can be included in the SDAP/PDCP/RLC header, etc. For example, the MAC layer can check the importance of data included in the RLC PDU through the RLC header information of the RLC PDU, and in this case, the importance of the data can be ultimately determined by the importance of the PDU set to which the data belongs.

Although the embodiments of the present invention below were written on the assumption that a lower importance value of a PDU set indicates a higher importance, the same method can also be applied to a case where a higher importance value of a PDU set indicates a higher importance. However, in this case, only the method of comparing the importance values of each PDU set to determine the relative importance is changed.

The above PDU set importance can be used to abandon transmission of data with relatively low importance (i.e., discard low importance data) when network congestion occurs and wireless resources in the network are not sufficient to transmit data waiting to be transmitted. The base station and the terminal can secure wireless resources required to transmit data packets with high importance by discarding data packets with low importance. In the case of downlink data, the downlink packet discarding operation can be determined according to the base station implementation. On the other hand, the uplink packet discarding operation performed in the terminal can be specified in the standard, and the terminal can perform the packet discarding operation according to the network setting. Therefore, the following embodiments of the present disclosure propose a method and apparatus for instructing a terminal to perform an uplink packet discarding operation based on PDU set importance when the base station recognizes a network congestion situation.

The above PDU set importance-based uplink packet discard operation (hereinafter referred to as 'PSI-based packet discard operation' for the sake of ease of explanation) can be performed on an uplink data packet (e.g., PDCP SDU/PDU, RLC SDU/PDU, MAC SDU/PDU) waiting for transmission in a Layer 2 layer (e.g., MAC, RLC, PDCP layer) of a terminal. At this time, the importance of each packet can be determined by the importance of a PDU set to which data included in the corresponding packet belongs. In the following embodiments of the present disclosure, the packet discard operation in the PDCP layer will be representatively described for the sake of ease of explanation. In this case, the unit of performing the packet discard operation can be a PDCP SDU or a PDCP PDU, and the entity performing the packet discard operation can be the PDCP layer. However, the embodiments of the present disclosure are not limited to the packet discard operation in the PDCP layer, and the unit of performing the packet discard operation and the entity performing the packet discard operation can vary depending on any one of the Layer 2 layers performing the packet discard operation. That is, the packet discard operation can be performed at any one of the Layer 2 layers, and accordingly, at least one of the PDCP SDU, PDCP PDU, or RLC SDU, RLC PDU, or MAC SDU, MAC PDU can be the target of the packet discard operation.

In addition, the above-described uplink packet discard operation (PSI-based packet discard operation) may be performed not in a single packet unit but in a PDU set unit (in other words, in a bundle unit of packets constituting the same PDU set). In the following embodiments (1d, 1e, 1f, 1g, 1h) of the present disclosure, for ease of explanation, the packet unit discard operation (e.g., PDCP SDU unit discard operation) will be representatively described. However, the embodiments of the present invention are not limited to the packet unit discard operation, and may be equally applied to the PDU set unit discard operation (PDU set discarding) as specifically described in FIG. 1j below. (However, in this case, the operations described in a packet unit may be changed to a PDU set unit.)

FIG. 1d illustrates an operation and procedure for a terminal to discard an uplink transmission packet based on PDU set importance according to a network instruction according to one embodiment of the present disclosure.

The gNB (1d-02) can detect network congestion based on the status of schedulable radio resources, etc. In particular, if the gNB determines that uplink data of all UEs cannot be scheduled within a required delay time due to insufficient uplink radio resources, the gNB can transmit a network congestion indicator (1d-07) to the UE (1d-01). The network congestion indicator can be defined as an indicator indicating a network congestion situation to the UE. In this case, the network congestion indicator can be used as an indicator that triggers various operations that the UE should perform when a network congestion situation occurs. Alternatively, the network congestion indicator can be defined as an indicator for instructing the UE to perform an uplink packet discard operation based on PDU set importance (hereinafter, referred to as PDU Set Importance, PSI for ease of explanation). The following options can be considered as a method for transmitting the network congestion indicator.

- SIB (System Information Block) (1d-12)

: The SIB may include an indicator for indicating network congestion. In this case, the gNB may transmit the network congestion indicator to UEs within the cell coverage on a cell-by-cell basis by broadcasting a SIB message. When the UE receives the network congestion indicator through the SIB message, the UE may perform a PSI-based packet drop operation for all DRBs to which the PDU set is mapped (or all DRBs related to the PDU set) (e.g., a DRB to which a PDCP SDU with PSI information is mapped, a DRB configured to process PSI information, a DRB configured to handle packets on a PDU set-by-PDU set basis, etc.) (1d-18).

- MAC CE (MAC Control Element) (1d-14)

: A new MAC CE may be defined to indicate network congestion. In this case, the gNB may transmit a network congestion indicator per UE by transmitting the MAC CE to a specific UE. When the UE receives the network congestion indicator via the MAC CE, the UE may perform a PSI-based packet drop operation for all DRBs to which the PDU set is mapped (or all DRBs related to the PDU set) (e.g., DRBs to which PDCP SDUs with PSI information are mapped, DRBs configured to handle PSI information, DRBs configured to handle packets per PDU set, etc.) (1d-18).

Additionally, the MAC CE may indicate one or more DRBs set to the UE. In this case, the UE may perform PSI-based packet discarding operation only for the DRB(s) indicated via the MAC CE (1d-18).

- DCI (1d-14)

: A new DCI may be defined or an existing DCI may be used to indicate network congestion. In this case, the gNB may transmit a network congestion indicator per UE by transmitting the DCI to a specific UE. When the UE receives the network congestion indicator via the DCI, the UE may perform a PSI-based packet drop operation for all DRBs to which the PDU set is mapped (or all DRBs related to the PDU set) (e.g., a DRB to which a PDCP SDU with PSI information is mapped, a DRB configured to process PSI information, a DRB configured to handle packets per PDU set, etc.).

Alternatively, when the UE receives a network congestion indicator through the DCI, the UE may perform a PSI-based packet discard operation for DRBs that use cellgroup resources that received the DCI (i.e., DRBs mapped to RLC entities that use the cellgroup resources) among DRBs to which the PDU set is mapped (or DRBs related to the PDU set) (e.g., DRBs to which a PDCP SDU with PSI information is mapped, DRBs configured to process PSI information, DRBs configured to handle packets in units of PDU sets, etc.) (1d-18).

- PDCP control PDU (1d-16)

: A new PDCP control PDU can be defined to indicate network congestion. In this case, the gNB can transmit a network congestion indicator to a specific UE on a DRB basis by transmitting the PDCP control PDU over a specific DRB configured for the specific UE. When the UE receives the network congestion indicator through the PDCP control PDU, the UE can perform a PSI-based packet drop operation for the DRB connected to the PDCP entity that received the PDCP control PDU (1d-18).

1d-22 of Fig. 1d shows an uplink packet discarding operation in the PDCP layer of UE (1d-01). When uplink data packets (e.g., PDCP SDUs) arrive at the PDCP layer of the UE, the packets are sequentially stored in the Layer 2 buffer of the UE. In 1d-22 of Fig. 1d, the packet that arrives first in the Layer 2 buffer is packet (1d-24), and the packet that arrives latest is represented as packet (1d-26). The PDCP layer can start a timer (discardTimer) for packet discarding operation for each packet when the uplink data packet arrives. For example, referring to Fig. 1d, discardTimer (1d-28) can be started when packet (1d-26) arrives. Expiration of the discardTimer may mean that transmission of the corresponding packet (e.g., PDCP SDU) is no longer valid. In other words, the receiver may no longer use the packet even if it receives it because the transmission delay time of the packet exceeds a certain threshold. Therefore, the PDCP layer may discard the packet when the discardTimer associated with the packet expires.

The UE may perform a PSI-based packet discard operation separately from the discardTimer-based packet discard operation described above when network congestion is indicated (1d-30) by at least one of the methods (1d-10, 1d-12, 1d-14, 1d-16). When network congestion is indicated from the network (1d-30), the UE may immediately discard low-priority packets (1d-24, 1d-32, 1d-34) among the uplink packets waiting for transmission in the Layer 2 buffer at that time, regardless of whether the discardTimer has expired. At this time, the importance value of each packet (e.g., PDCP SDU) may be the importance value (in other words, PSI) of a PDU set composed of data included in the packet. In Fig. 1d, for ease of explanation, it is assumed that the PSI value has two values, such as {1, 0}, {true, false}, and {high, low}. However, if the PSI value is defined as a more diverse value, such as an integer from 0 to 8, parameters for indicating which packets with which PSI values are to be discarded when the UE performs a PSI-based packet discard operation can be newly defined and set by the base station. The operation is specifically described in the embodiment of Fig. 1e below.

As described above, in case of network congestion, the gNB can instruct the UE to perform PSI-based packet drop operation through the network congestion indicator, thereby instructing the UE to drop low-priority packets and use limited uplink transmission resources for high-priority packets. This operation can help improve the user satisfaction with XR service quality by enabling transmission of high-priority packets even when network congestion occurs.

FIG. 1e illustrates various operation methods and procedures for a terminal to discard uplink transmission packets based on PDU set importance according to a network instruction according to one embodiment of the present disclosure.

The PSI-based packet discard operation described in the above Fig. 1d assumes only the case where the PSI value has two values, such as {1, 0}, {true, false}, {high, low}. In this case, the gNB (1e-02) only indicates whether the network is congested through the network congestion indicator without any additional configuration parameters, and the UE (1e-01) can discard low-priority packets through the PSI-based packet discard operation, as in Case 0 (1e-20) of Fig. 1e. However, the PSI value can be defined to have more diverse values, such as values between 0 and 8. In this case, when the UE (1e-01) performs the PSI-based packet discard operation according to the network congestion indication of the gNB (1e-02), the following variables can be additionally transmitted from the gNB to the UE in order to specifically indicate which PSI values packets to discard. Meanwhile, the following description will exemplify a case where the PSI value has a value between 0 and 8, but the embodiments of the present disclosure are not limited thereto. The PSI value may have a variety of values in a range depending on the criteria for distinguishing importance, such as a value between 0 and 1 (same as described above), a value between 0 and 3, a value between 0 and 15, etc.

- PSI value (or list of PSI values)

: For a PSI-based packet drop operation, a PSI value or a list of PSI values for which a packet drop operation should be performed can be transmitted to the UE. In this case, as in Case 1 (1e-21), the UE can perform a packet drop operation for packets having PSI values included in the PSI value or the list of PSI values set by the gNB.

- PSI value range

: For a PSI-based packet drop operation, a range of PSI values for which a packet drop operation should be performed can be transmitted to the UE. In this case, as in Case 2 (1e-23), the UE can perform a packet drop operation for packets having PSI values that fall within the range (2 to 3) of PSI values set by the gNB.

- PSI threshold

: For the PSI-based packet drop operation, a threshold value of the PSI value at which the packet drop operation should be performed can be transmitted to the UE. In this case, as in Case3 (1e-25), the UE can perform the packet drop operation for packets having a PSI value higher or lower than the PSI threshold value (2) set by the gNB. In the 1e-25 example, it is assumed that the lower the PSI value, the higher the importance, and packets having a PSI value (3) higher than the set threshold value (2) are dropped.

- Timer threshold

: When performing a PSI-based packet discard operation, packets that have just arrived in the Layer2 buffer of the UE (i.e., packets whose remaining time (time remaining until discardTimer expiration) value is still large) can be excluded from the packet discard operation. To this end, the gNB can transmit a timer threshold value to the UE together with the above-mentioned PSI-related variables (at least one of the PSI value/list, PSI range, and PSI threshold value). Case 1a (1e-27) represents a case where the gNB sets the timer threshold value (1000 msec) together with the PSI value (3). In this case, the UE can discard only packets among the packets with the PSI value 3 whose remaining time (time remaining until discardTimer expiration) value is smaller than the timer threshold value.

The gNB may use one of the following two options to configure at least one of the variables (e.g. PSI value/list, PSI range, PSI threshold, timer threshold) to the UE.

- Option 1: The gNB can set variables required for PSI-based packet discard operation to the UE through the RRCReconfiguration message (1e-05). In this case, when the gNB detects network congestion (1e-10), it can transmit only a network congestion indicator (1e-13) to the UE without having to additionally transmit separate variables. After receiving the network congestion indicator in step 1e-13, the UE can perform PSI-based packet discard operation using the variables set in step 1e-05 (1e-15). At this time, at least one of the SIB (1d-12), MAC CE (1d-14), DCI (1d-16), and PDCP control PDU (1d-16) described in the drawing 1d can be used as the network congestion indicator in step 1e-13.

- Option 2: When the gNB detects network congestion (1e-10), it can set variables required for PSI-based packet drop operation to the UE together with a network congestion indicator (1e-13). At this time, as the network congestion indicator of step 1e-13, at least one of SIB (1d-12), MAC CE (1d-14), DCI (1d-16), PDCP control PDU (1d-16) described in the drawing 1d can be used. After receiving the network congestion indicator at step 1e-13, the UE can perform the PSI-based packet drop operation using the variables set together with the indicator (1e-15).

Additionally, the gNB may set the DRB ID and LCID to which the PSI-based packet discarding operation will be applied while indicating network congestion to the UE at step 1e-13.

FIG. 1f illustrates an operation and procedure for a terminal to discard PDCP SDUs based on PDU set importance for a specific time period according to a network instruction according to an embodiment of the present disclosure.

When gNB (1f-02) detects network congestion (1f-05), it can share the network congestion situation with UE (1f-01) through network congestion indicator (1f-07) and instruct PSI-based packet drop operation. At this time, as the network congestion indicator of step 1f-07, at least one of SIB (1d-12), MAC CE (1d-14), DCI (1d-16), PDCP control PDU (1d-16) described in the above-mentioned FIG. 1d can be used. In the embodiment of the above-mentioned FIG. 1d, an operation of one-time drop of packets in the Layer 2 buffer based on the PSI value at the time when the UE receives the network congestion indicator from the gNB is described. However, considering that network congestion can generally last for a certain period of time once it occurs, the gNB can set the UE to continue the PSI-based packet drop operation for a certain period of time during which the network congestion continues (or is expected to continue). For this purpose, at least one of the following two options can be used.

- Option 1: When the gNB detects (1f-05) a network congestion situation (or, when the gNB detects a network congestion situation and the congestion situation is expected to continue for a certain period of time), the gNB may transmit a network congestion indicator to the UE (1f-07) together with a time duration (1f-10) value during which a PSI-based packet discard operation should be performed. When the UE receives the network congestion indicator (1f-07) together with a specific time duration value (1f-10), the UE may start (1f-13) a PSI-based packet discard operation and continue the PSI-based packet discard operation for the specific time duration (1f-10).

- Option 2: The gNB may detect network congestion (1f-05) and transmit a network congestion indicator (1f-07) to the UE. When the UE receives the network congestion indicator (1f-07), the UE may start a PSI-based packet drop operation (1f-13) and continue the PSI-based packet drop operation until it receives an indication (1f-15) from the gNB that the network congestion has been resolved. Thereafter, the gNB may detect that the network congestion has been resolved (1f-14) and instruct the UE that the network congestion has been resolved (1f-15). At this time, a method may be used that does not include an indicator used as a network congestion indicator in step 1f-07 to instruct network congestion relief, or a method may be used that defines a new indicator to explicitly instruct network congestion relief. When the UE receives an indication (1f-15) from the gNB that network congestion has been resolved, the UE may stop (1f-17) the PSI-based packet drop operation.

Through the above-described Option 1 or Option 2 method, the UE can start (1f-30) a PSI-based packet discard operation and continue it for a certain period of time before ending it (1f-31). When starting the PSI-based packet discard operation, the UE can immediately discard low-priority packets (1f-24, 1f-32, 1f-34) among the uplink packets waiting for transmission in the Layer 2 buffer at that time, regardless of whether the discardTimer has expired.

After that, while maintaining the PSI-based packet discard operation, if the importance of a new packet arrival is low (1f-26), the UE can immediately discard the packet. For packets that have arrived previously and are newly arrived but are not discarded, the discardTimer-based packet discard operation (e.g., PDCP SDU discarding operation) can be performed as before. After that, when the network congestion time duration set by the gNB ends or the gNB instructs the UE to resolve network congestion, the UE stops the PSI-based packet discard operation and can perform the discardTimer-based packet discard operation as before for newly arrived packets regardless of their importance. For the convenience of explanation, in Fig. 1f, it is assumed that the PSI value has two values, {1, 0}, {true, false}, {high, low}. However, in cases where the PSI values are defined as more diverse values, such as integers from 0 to 8, parameters for indicating which packets with which PSI values are to be discarded when the UE performs PSI-based packet discarding operation can be newly defined and set by the base station. The operation is as described in the embodiment of Fig. 1e above.

FIG. 1g illustrates an operation and procedure for a terminal to use a separate discarding timer value per PDU set importance unit according to a network instruction according to one embodiment of the present disclosure.

The PDCP layer of the UE (1g-01) can perform a PDCP SDU discarding operation based on a discarding timer as described in the embodiment of the above-described FIG. 1d. Specifically, the PDCP layer of the UE starts a discardTimer (1g-25) for packet discarding operation for each packet when an uplink data packet (PDCP SDU) arrives, and when the discardTimer of a specific packet expires, the transmission of the corresponding packet can be abandoned and discarded. At this time, the discardTimer value is set for each PDCP entity connected to each DRB, so that the same discardTimer value (1g-25) can be used for all PDCP SDUs arriving at the corresponding DRB (PDCP entity). At this time, the discardTimer (1g-25) can mean at least one discardTimer that is started before receiving an instruction (Activation indication) to use a separate discardTimer value according to importance in FIG. 1g.

In addition, in order to discard low-priority packets relatively quickly and increase the transmission success rate of high-priority packets when network congestion occurs, a separate discardTimer value (1g-30, 1g-32, 1g-35) may be set and used according to the importance of each packet during the PDCP SDU discarding operation. More specifically, a relatively short discardTimer value (1g-35) may be set for packets with relatively low importance, and a relatively long discardTimer value (1g-32) may be set for packets with relatively high importance. In this case, when uplink packets are delayed in transmission due to network congestion and the waiting time in the Layer2 buffer of the UE becomes long, the discardTimers of packets with relatively low importance may expire first, so that low-priority packets may be discarded first and the possibility of successful transmission of packets with relatively high importance may increase.

The gNB (1g-02) can configure (instruct) the UE (1g-01) to use one identical discardTimer value per DRB (per PDCP entity connected to the corresponding DRB) or to use separate discardTimer values according to the importance of each uplink packet, depending on the network congestion status (1g-40). The specific step-by-step operations are as follows.

In step 1g-05, the gNB may transmit an RRCReconfiguration message to the UE. The gNB may set a discardTimer value to be used for the PDCP SDU discarding operation through the RRC message. At this time, the gNB may set one discardTimer value to be used per DRB unit (per PDCP entity unit connected to the corresponding DRB). In addition, the gNB may set a separate discardTimer value per UE unit or per DRB unit (per PDCP entity unit connected to the corresponding DRB) according to the importance of the packet. Here, the packet may mean a PDCP SDU, and the importance of each packet may be the importance (PSI) value of a PDU set composed of data included in the corresponding packet. In addition, the gNB may set (instruct) whether to use a separate discardTimer value per packet importance depending on a network congestion situation per DRB unit (per PDCP entity unit connected to the corresponding DRB). At least one of the above-described configuration information may be set through the RRCReconfiguration message. That is, at least one of the following information indicating whether a single discardTimer value to be used per DRB unit, a discardTimer value set per UE or per DRB unit according to packet importance, or a separate discardTimer value according to packet importance can be used can be set via the RRCReconfiguration message.

In step 1g-07, the UE can perform PDCP SDU discarding operation using one discardTimer value set per DRB (per PDCP entity connected to the corresponding DRB) in step 1g-05. Accordingly, the same discardTimer value is applied to all uplink packets arriving at the PDCP entity connected to the corresponding DRB.

At step 1g-10, the gNB can detect that a network congestion situation has occurred.

In step 1g-12, the gNB may transmit (set) to the UE an indicator to activate an operation in which the UE uses a separate discardTimer value according to the importance of each packet. Alternatively, the indicator may be defined to be used as an indicator that triggers various operations that the UE should perform when a network congestion situation occurs. At least one of MAC CE, DCI, PDCP control PDU may be used as the indicator in the manner described in the drawing 1d, and at least one of the following variables may be included.

- Time duration (1g-13): The time value at which the UE should use a separate discardTimer value according to the importance of the packet may be included. If the Time duration value is set together in step 1g-12, the UE can maintain the operation of using a separate discardTimer value according to the importance of each packet for the Time duration. If the Time duration value is not set together in step 1g-12, the UE can maintain the operation of using a separate discardTimer value according to the importance of each packet until it receives a deactivation instruction from the gNB as in step 1g-20 below.

- DiscardTimer values by importance: If separate discardTimer values by importance are not set through RRC signaling in step 1g-05, the values can be set together in step 1g-12.

- DRB ID to be activated: The ID value of one or more target DRBs for which the UE should activate the operation of using a separate discardTimer value according to the importance of each packet may be included.

At step 1g-17, the gNB can detect that network congestion has been resolved.

In step 1g-20, the gNB may transmit (set) to the UE an indicator to disable the operation of the UE using a separate discardTimer value according to the importance of each packet. Alternatively, the indicator may be defined to be used as an indicator that triggers various operations that the UE should perform when resolving a network congestion situation. At least one of MAC CE, DCI, and PDCP control PDU may be used as the indicator, and at least one of the following variables may be included.

- DRB ID to be disabled: The ID value of one or more target DRBs for which the UE should disable the operation of using a separate discardTimer value according to the importance of each packet may be included.

Additionally, the gNB may set the discardTimer value for a specific packet importance to '0' in the discardTimer setting and instruction of steps 1g-05 and 1g-12 so that the UE immediately discards uplink packets (PDCP SDUs) with the corresponding importance upon arrival at the PDCP layer.

FIG. 1h illustrates an operation and procedure for changing a PDCP discarding timer value used in a PDCP layer for each DRB unit of a terminal according to a network instruction according to one embodiment of the present disclosure.

The PDCP layer of the UE (1h-01) can perform a PDCP SDU discarding operation based on a discarding timer as described in the embodiment of the above-described Fig. 1d. Specifically, the PDCP layer of the UE starts a discardTimer (1h-20) for packet discarding operation for each packet unit when an uplink data packet (PDCP SDU) arrives, and when the discardTimer of a specific packet expires, the transmission of the corresponding packet can be abandoned and discarded. At this time, the discardTimer value is set for each PDCP entity connected to each DRB, and the same discardTimer value (1h-20) can be used for all PDCP SDUs arriving at the corresponding DRB (PDCP entity).

In addition, gNB (1h-02) can alleviate network congestion by relatively quickly discarding packets waiting to be transmitted by UE (1h-01) when network congestion occurs. To this end, the gNB can set one or more multiple discardTimer values (1h-20 and 1h-25) for each DRB of the UE and instruct (1h-17) to use one of the values depending on the network congestion situation. The specific step-by-step operations are as follows.

At step 1h-05, the gNB may transmit an RRCReconfiguration message to the UE. The gNB may set a discardTimer value to be used for PDCP SDU discarding operation in the PDCP layer of the UE through the RRC message. At this time, the gNB may set one or more discardTimer values to be used per DRB unit (per PDCP entity unit connected to the corresponding DRB). At this time, when multiple discardTimer values are set for a specific DRB, each discardTimer value may be linked to a specific ID (or index) value and set in the form of a list, and the gNB may instruct (set) which value among the multiple discardTimer values set per DRB unit the UE should use together using the ID or index value.

Alternatively, the gNB may set only two discardTimer values to be used per DRB unit (per PDCP entity unit connected to the corresponding DRB). When only two discardTimers are set, one of them may be a default value (in other words, a value used basically when there is no additional setting or instruction) and the other may be a value that can be used in a network congestion situation (in other words, a value that can be used according to the setting and instruction of the gNB in a network congestion situation). When only two discardTimer values are set in this way per DRB unit, they may be distinguished by being defined as separate fields without using separate ID and index values. In addition, the gNB may set (instruct) whether the discardTimer value of each DRB unit (per PDCP entity unit connected to the corresponding DRB) can be dynamically changed depending on the network congestion situation. In this embodiment, it is assumed that T1 (1h-20) is set (instructed) to be used as the discardTimer value.

In step 1h-07, the UE may perform PDCP SDU discarding operation using the value (T1, 1h-20) instructed to be used among one or more discardTimer values set per DRB (per PDCP entity connected to the corresponding DRB) in step 1h-05. Accordingly, the same discardTimer value (T1, 1h-20) is applied to all uplink packets arriving at the PDCP entity connected to the corresponding DRB.

At step 1h-10, the gNB can detect that a network congestion situation has occurred.

In step 1h-12, the gNB may transmit (configure) to the UE an indicator instructing the UE to use a different discardTimer value for a specific DRB. Alternatively, the indicator may be defined to be used as an indicator that triggers various operations that the UE should perform when a network congestion situation occurs. At least one of MAC CE, DCI, PDCP control PDU as described in the drawing 1d may be used as the indicator, and at least one of the following variables may be included.

- DRB ID to be activated: One or more ID values of the DRBs for which the UE activates the operation of changing the discardTimer value may be included.

- discardTimer ID (or index): If multiple discardTimer values are set per DRB in step 1h-05, each discardTimer value can be set with a specific ID (or index) value. The gNB can include the DRB ID and the discardTimer ID (or index) value to instruct (activate) the UE to use one of the multiple discardTimer values set in step 1h-05 for a specific DRB.

For example, assuming that MAC CE is used to indicate discardTimer activation in step 1h-12, 5 bits out of 8 bits configuring the MAC CE may be used to indicate a specific DRB ID and the remaining 3 bits may be used to indicate one of multiple discardTimer values set for the DRB in step 1h-05. In addition, in order to indicate a discardTimer value to be used in each DRB for a plurality of DRBs, a plurality of 8-bit information consisting of DRB ID and discardTimer ID values as described above may be included in the MAC CE in the form of a list. When the UE receives the MAC CE configured in the above format, it starts using the indicated discardTimer value for each DRB.

In addition, if only two discardTimer values are set for each DRB in the step 1h-05, a zero size MAC CE (a MAC CE without a payload of the MAC CE itself) can be defined, and the discardTimer value to be used in a network congestion situation can be activated and deactivated only with (e)LCID. In this case, MAC CEs for activating and deactivating the discardTimer value to be used in a network congestion situation are separately defined, and the two MAC CEs can be distinguished through the (e)LCID of each MAC CE. The UE, which has received one of the two MAC CEs, can activate or deactivate the discardTimer value to be used in a network congestion situation for all DRBs (or all DRBs for which two discardTimer values are set) for which the discardTimer value is set (instructed) to be dynamically changed depending on the network congestion situation in the step 1h-05 simultaneously.

- DRB-specific discardTimer value: If multiple discardTimer values are not set for each DRB through RRC signaling in step 1h-05, a discardTimer value to be used in a specific DRB can be set in step 1h-12. In other words, a specific DRB ID and a specific discardTimer value can be indicated. In this case, the UE can use the indicated discardTimer value for the corresponding DRB.

At step 1h-15, the UE can perform PDCP SDU discarding operation using the changed discardTimer value for each DRB according to the instruction at step 1h-12. The UE can apply the changed discardTimer (T2, 1h-25) value to packets (PDCP SDUs) arriving after the time point (1h-17) at which the gNB instructed to change the discardTimer value for a specific DRB (or multiple DRBs).

Additionally, the gNB may also configure the UE to immediately discard all uplink packets (PDCP SDUs) arriving at the PDCP layer of a specific DRB by setting the discardTimer value for that DRB to '0' in the discardTimer setting and instruction of steps 1h-05 and 1h-12.

FIG. 1i illustrates a procedure for a terminal to report information about uplink packets waiting for transmission to a base station to help indicate PDCP discarding operation based on PDU set importance of a network according to one embodiment of the present disclosure.

UE (1i-01, 1i-11, 1i-21) can report to gNB information that can be helpful when gNG (1i-02, 1i-12, 1i-22) sets packet discard operation (e.g., PDCP SDU discarding) based on packet importance (e.g., importance of PDU set to which data included in each packet belongs, PSI) described in FIGS. 1d, 1e, 1f, 1g. For reference, since there is no method for gNB to determine importance (e.g., PSI value) of packets transmitted by UE through uplink according to the current specification, it is difficult to set packet importance based packet discard operation described in FIGS. 1d, 1e, 1f, 1g. To solve this problem, UE can provide at least one of the following information (hereinafter, referred to as 'PSI-based terminal assistance information' for ease of explanation) to gNB. For reference, PSI-based terminal assistance information can be calculated (configured) and reported in DRB/RLC/LCH units.

- The importance of uplink packets waiting to be transmitted at the terminal (i.e., PSI)

: A list of importance values (PSIs) of uplink packets (at least one of PDCP SDU/PDU, RLC SDU/PDU, MAC SDU/PDU) waiting for transmission in the Layer2 buffer of the UE can be reported to the gNB. For example, if uplink packets with importance of 1, 2, and 3 are waiting for transmission in the Layer2 buffer of the UE, the UE can report the importance values of the corresponding packets to the gNB in the form of a list. Alternatively, the UE can report only the largest (or smallest) importance values (PSIs) of the uplink packets waiting for transmission in the Layer2 buffer to the gNB.

- The amount of uplink packets waiting to be transmitted for each importance level.

: The amount of uplink packets waiting to be transmitted in the Layer2 buffer of the UE can be reported by importance value (PSI). For example, the UE can report to the gNB the sum of the sizes of uplink packets waiting to be transmitted in the Layer2 buffer by importance. Alternatively, the UE can report to the gNB the ratio of packets having each importance value (PSI) out of the total size of uplink packets waiting to be transmitted in the Layer2 buffer. For example, when the total size of packets waiting to be transmitted in the Layer2 buffer of the UE is 100 MB, if the total size of packets with an importance value of 1 is 30 MB, the total size of packets with an importance value of 2 is 20 MB, and the total size of packets with an importance value of 3 is 50 MB, then 30%, 20%, and 50% for importance values of 1, 2, and 3, respectively, can be reported to the gNB.

- Satisfaction of QoS requirements (e.g. PSER, PER, PSDB, PDB, etc.) for each importance level

: The UE can report to the gNB whether the following QoS requirements are satisfied when transmitting an uplink packet with the corresponding importance for each importance value (PSI).

* Packet Error Rate (PER)

* Packet Delay Budget (PDB)

* PDU Set Error Rate (PSER): defines an upper bound for a rate of non-congestion related PDU Set losses between RAN and the UE.

* PDU Set Delay Budget (PSDB): time between reception of the first PDU (at the UPF in DL, at the UE in UL) and the successful delivery of the last arrived PDU of a PDU Set (at the UE in DL, at the UPF in UL). PSDB is an optional parameter and when provided, the PSDB supersedes the PDB.

- L2 transmission delay time for each importance

: The UE can measure the average delay time from the time when uplink packets with each importance value arrive at the Layer 2 buffer until the actual transmission is completed, and report this to the gNB.

Specifically, the PSI-based terminal assistance information described above can be reported from the UE to the gNB by at least one of the following methods.

- How to use UE Assistance Information (UAI) (1i-00):

The gNB (1i-02) configures the UE (1i-03) to report PSI-based terminal assistance information using UAI, and the UE can report PSI-based terminal assistance information by including it in a UAI message according to the gNB configuration.

In step 1i-03, the gNB can determine that a network congestion situation has occurred. The gNB may require PSI-based UE assistance information to set up a PSI-based packet drop operation according to the network congestion situation. Therefore, the gNB may set up the UE to report PSI-based UE assistance information via a UAI message in step 1i-04. More specifically, at least one of the following variables may be included in the corresponding setting information.

* prohibitTimer: A separate prohibitTimer value may be set to prevent the UE from reporting PSI-based terminal assistance information via UAI messages too frequently. The UE cannot transmit a new UAI message for reporting PSI-based terminal assistance information while the prohibitTimer set in relation to PSI-based terminal assistance information is running.

* Setting reporting conditions: Variables related to conditions for triggering reporting of PSI-based terminal assistance information by the UE can be set. For example, if the gNB wants to receive reports of PSI-based terminal assistance information periodically from the UE, a reporting cycle can be set. As another example, if the gNB wants to receive reports of PSI-based terminal assistance information when the delay time experienced by uplink packets in the Layer2 buffer of the UE exceeds a specific threshold, the threshold can be set.

* Setting report information: Variables indicating information to be included when the UE reports PSI-based terminal assistance information can be set. For example, an indicator indicating whether the UE should report the corresponding information by including it in a UAI message for each piece of information included in the PSI-based terminal assistance information can be included. In addition, DRB/RLC/LCID, etc. to which the PSI-based terminal assistance information should be reported can be indicated together.

At step 1i-06, if the UE has not yet sent a UAI message including PSI-based terminal assistance information after receiving the PSI-based terminal assistance information reporting configuration via UAI message at step 1i-04, the UE may trigger transmission of a UAI message for reporting PSI-based terminal assistance information. The UE may report PSI-based terminal assistance information via UAI message according to the gNB instruction at step 1i-04.

In step 1i-07, a condition for reporting PSI-based terminal assistance information via UAI message may be satisfied. The reporting condition may be set from the gNB as in the example described in step 1i-04. Alternatively, a condition for reporting PSI-based terminal assistance information via UAI may be specified in the specification. For example, if a PDCP SDU discarding operation occurs in the PDCP layer of a specific DRB of the UE and there is PSI-based terminal assistance information measured (or calculated) for the corresponding DRB, the UE may trigger transmission of a UAI message for reporting PSI-based terminal assistance information.

In step 1i-09, the UE may transmit the UAI message triggered for reporting PSI-based terminal assistance information in step 1i-07. However, if the prohibitTimer configured for PSI-based terminal assistance information reporting is running, the UAI transmission may be delayed.

- How to use UE Information Request/Response (1i-10):

The gNB (1i-12) may request the UE (1i-13) to report PSI-based terminal assistance information via a UE Information Request message. The UE may respond by including the PSI-based terminal assistance information in the UE Information Response message according to the gNB request.

In step 1i-13, the gNB can determine that a network congestion situation has occurred. The gNB may require PSI-based UE assistance information to set up a PSI-based packet drop operation depending on the network congestion situation. Therefore, the gNB can request the UE to report PSI-based UE assistance information through a UE Information Request message in step 1i-15 below.

At step 1i-15, the gNB may request the UE to report PSI-based terminal assistance information via a UE Information Request message via a UE Information Response message. More specifically, at least one of the following variables may be included in the UE Information Request message.

* Setting report information: Variables indicating information to be included when the UE reports PSI-based terminal assistance information may be set together. For example, an indicator indicating whether the UE should report the corresponding information by including it in the UE Information Response message may be included for each piece of information included in the PSI-based terminal assistance information. In addition, DRB/RLC/LCID, etc. to which the PSI-based terminal assistance information should be reported may be indicated together.

In step 1i-17, the UE may trigger transmission of a UE Information Response message for reporting PSI-based terminal assistance information after receiving a request for reporting PSI-based terminal assistance information through a UE Information Request message in step 1i-15. The UE may report PSI-based terminal assistance information through a UE Information Response message according to the gNB instruction in step 1i-15.

- How to use PDCP control PDU (1i-20):

The gNB (1i-22) configures the UE (1i-23) to report PSI-based terminal assistance information using the PDCP control PDU, and the UE can transmit the PDCP control PDU containing the PSI-based terminal assistance information according to the gNB configuration.

At step 1i-24, the gNB can configure the UE to report PSI-based terminal assistance information via PDCP control PDU. At this time, the DRB/RLC/LCID, etc., to which the PDCP control PDU including the PSI-based terminal assistance information should be transmitted can be indicated together.

In step 1i-27, a transmission condition of a PDCP control PDU including PSI-based terminal assistance information may be satisfied. The above reporting condition may be specified in the specification. For example, if a PDCP SDU discarding operation occurs in the PDCP layer of a specific DRB of the UE, a PDCP control PDU including PSI-based terminal assistance information may be triggered to be transmitted to the gNB from the PDCP entity of the corresponding DRB of the UE.

In step 1i-29, the UE can transmit a PDCP control PDU containing the PSI-based terminal assistance information triggered in step 1i-27.

FIG. 1j illustrates a PDU set discarding operation method in a PDCP layer according to one embodiment of the present disclosure.

The discardTimer-based uplink packet discarding operation (i.e., PDCP SDU discarding operation) described in the embodiments of the above drawings 1d, 1e, 1f, 1g, and 1h can be performed not only on a single packet (e.g., PDCP SDU/PDU) basis but also on a PDU set basis. The specific PDU set-based packet discarding (i.e., PDU set discarding) operation method is as described below.

Referring to FIG. 1j, when a specific PDU (1j-12) among the PDUs constituting the PDU set (1j-10) is discarded (or discarded) due to expiration of the discardTimer, the PDCP layer of the terminal may perform a PDU set discarding operation to discard the remaining PDUs (1j-11, 1j-13, 1j-14, 1j-15, 1j-16) constituting the PDU set for efficient use of radio resources. At this time, the remaining PDUs may mean 'PDUs not yet transmitted' among the PDUs constituting the PDU set or 'PDUs having a higher SN (sequence number) than the discarded PDUs'. In addition, 'PDU set' and 'PDU' here may mean PDUs in a PDCP upper layer, and may mean PDCP SDUs in the PDCP layer. This PDU set discarding operation (or ADU discarding) can enable efficient use of radio resources by discarding other PDUs belonging to the PDU set when any one of the PDUs constituting the PDU set is discarded, making transmission of the PDU set no longer meaningful.

PDU set discarding operation can be set per DRB. To set PDU set discarding operation, 1-bit indicators such as 'PDU_SetDiscardEnabled', 'PDU_SetDiscard', 'ADU_DiscardEnabled', and 'ADU_Discard' can be newly defined in PDCP-Config of DRB. The base station can set PDU set discarding operation for a specific DRB through the newly defined indicator in PDCP-Config of DRB. In addition, the base station can transmit the IDs of DRBs that must perform PDU set discarding operation to the terminal in the form of a list, and the terminal can perform PDU set discarding operation in the PDCP entity corresponding to the DRBs.

In addition, instead of setting the PDU set discarding operation setting on a DRB basis, the base station can set the PDU set discarding operation on a terminal basis. In case of setting the PDU set discarding operation on a terminal basis, the base station can transmit a 1-bit indicator, such as 'PDU_SetDiscardEnabled', 'PDU_SetDiscard', 'ADU_DiscardEnabled', or 'ADU_Discard', to a specific terminal to set the PDU set discarding operation. Accordingly, a terminal that receives the 1-bit indicator can perform the PDU set discard operation on all DRBs set in the terminal for which the discardTimer is set and for which the configuration information for the PDU set (e.g., PDU set index information) is provided from the upper layer.

The operation of the discardTimer in the PDCP layer may vary depending on whether the PDU set discarding operation is required. If the PDUs (i.e., PDCP SDUs) that constitute the PDU set that requires the PDU set discarding operation arrive at the PDCP layer, the PDCP entity may operate the discardTimer for each PDU set in order to perform the discarding operation for each PDU set.

Specifically, a PDCP entity can start a discardTimer corresponding to a specific PDU set when the first PDU constituting the PDU set arrives at the PDCP layer. Afterwards, when the discardTimer corresponding to the PDU set expires, the PDCP entity can discard all PDUs (i.e., PDCP SDUs) constituting the PDU set together. On the other hand, when PDUs (i.e., PDCP SDUs) constituting a PDU set that does not perform the PDU set discarding operation arrive at the PDCP layer, the PDCP entity can operate the discardTimer for each PDU (i.e., PDCP SDU) regardless of the PDU set. Specifically, the PDCP layer can start a discardTimer corresponding to each PDU (i.e., PDCP SDU) when the PDU arrives at the PDCP layer. Afterwards, when the discardTimer corresponding to each PDU expires, the PDCP layer can discard the PDU. Such an operation can be reflected in the PDCP specification in at least one of the following two options. When using Option 1 among the options below, it is possible to minimize changes in the existing terminal implementation that operates the discardTimer per PDCP SDU unit while realistically operating only one discardTimer per PDU set unit as in the case of Option 2.

In addition, even when PDUs (i.e., PDCP SDUs) constituting a PDU set that performs a PDU set discarding operation arrive at the PDCP layer, a method in which a PDCP entity operates a discardTimer for each PDU may also be considered. In this case, the PDCP entity may start a discardTimer corresponding to each PDU (i.e., PDCP SDU) constituting a specific PDU set at the time when the PDU arrives at the PDCP layer. Thereafter, when a discardTimer corresponding to any PDU (i.e., PDCP SDU) constituting the specific PDU set expires, the PDCP entity may discard all other PDUs (i.e., PDCP SDUs) constituting the PDU set together. However, in the case of the present embodiment, actual PDCP discarding is performed for each PDU set, which may cause inefficiency in that individual timers must be unnecessarily operated for each PDU.

Additionally, in relation to the network indication-based PDU or PDU set discarding operation described through the embodiments of FIGS. 1d, 1e, 1f, 1h, 1i and 1j, the following new UE Capability Information variables may be newly defined in the RRC UECapabilityInformation message.

- PDU set discarding support indicator: A new indicator may be introduced to indicate whether the terminal supports the PDU set discarding operation described in the above-described Fig. 1j. The terminal may report to the base station that it can perform the PDU set discarding operation through the indicator. The base station may configure the terminal to perform the PDU set discarding operation based on the indicator.

- PSI-based PDU/PDU set discarding support indicator: As in the embodiments of FIGS. 1d, 1e, and 1f, a new indicator may be introduced to indicate whether a terminal can perform a PSI (PDU Set Importance)-based PDU/PDU set discarding operation according to a network instruction. The terminal can report to the base station that it can perform the PSI-based PDU/PDU set discarding operation through the indicator. The base station can set the terminal to perform the PDU set discarding operation as in the embodiments of FIGS. 1d, 1e, and 1f based on the indicator. For reference, in order to indicate whether the terminal supports the PSI-based PDU/PDU set discarding operation, the new indicator may not be separately defined, and the PDU set discarding support indicator may be reused. In this case, whether the PDU set discarding operation can be supported and whether the PSI-based PDU/PDU set discarding operation can be supported may be indicated together through the PDU set discarding support indicator.

- PSI-specific Discard timer operation support indicator: A new indicator may be introduced to indicate whether a terminal can perform a PSI-specific discard timer operation as in FIG. 1g. The terminal can report to the base station that it can operate a separate discard timer for each PSI through the indicator. The base station can set the terminal to operate a separate discard timer for each PSI as in the embodiment of FIG. 1g based on the indicator. For reference, in order to indicate whether the terminal supports the PSI-specific Discard timer operation, the PDU set discarding support indicator may be reused instead of a new indicator being separately defined. In this case, whether the PDU set discarding operation can be supported and whether the PSI-specific Discard timer operation can be supported can be indicated together through the PDU set discarding support indicator.

- DRB unit discard timer change operation support indicator: A new indicator may be introduced to indicate whether the terminal can perform an operation of changing a discard timer value to be used in a specific DRB according to a network instruction as in the above Fig. 1h. The terminal can report to the base station through the indicator that it can perform an operation of changing a discard timer value to be used in a specific DRB according to a network instruction. Based on the indicator, the base station can set multiple discard timer values for each DRB of the corresponding UE as in the embodiment of Fig. 1h, and then instruct the terminal to use a specific discard timer value depending on a network situation.

- PSI-based terminal assistance information reporting operation support indicator: A new indicator may be introduced to indicate whether a terminal can perform a PSI-based terminal assistance information reporting operation according to a network instruction as in FIG. 1i. The terminal can report to the base station that it can perform the PSI-based terminal assistance information reporting operation through the indicator. The base station can instruct the terminal to report PSI-based terminal assistance information as in the embodiment of FIG. 1i based on the indicator. For reference, in order to indicate whether the terminal supports the PSI-based terminal assistance information reporting operation, the new indicator may not be defined separately and the PDU set discarding support indicator may be reused. In this case, whether the PDU set discarding operation can be supported and whether the PSI-based terminal assistance information reporting operation can be supported may be indicated together through the PDU set discarding support indicator.

FIG. 2 is a block diagram illustrating the internal structure of a terminal according to one embodiment of the present disclosure.

Referring to FIG. 2, the terminal includes an RF (Radio Frequency) processing unit (2-10), a baseband processing unit (2-20), a storage unit (2-30), and a control unit (2-40). Of course, the present invention is not limited to the above example, and the terminal may include fewer or more components than those illustrated in FIG. 2. The RF processing unit (2-10) may perform functions for transmitting and receiving signals through a wireless channel, such as signal band conversion and amplification. That is, the RF processing unit (2-10) up-converts a baseband signal provided from the baseband processing unit (2-20) into an RF band signal and transmits it through an antenna, and down-converts an RF band signal received through the antenna into a baseband signal. For example, the RF processing unit (2-10) may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC (digital to analog convertor), an ADC (analog to digital convertor), etc. In Fig. 2, only one antenna is illustrated, but the terminal may have multiple antennas. In addition, the RF processing unit (2-10) may include multiple RF chains. In addition, the RF processing unit (2-10) may perform beamforming. For beamforming, the RF processing unit (2-10) may adjust the phase and size of each signal transmitted and received through multiple antennas or antenna elements. In addition, the RF processing unit (2-10) may perform MIMO (multi input multi output) and may receive multiple layers when performing a MIMO operation. The RF processing unit (2-10) may appropriately set multiple antennas or antenna elements under the control of the control unit (2-40) to perform reception beam sweeping, or adjust the direction and beam width of the reception beam so that the reception beam is coordinated with the transmission beam.

The baseband processing unit (2-20) can perform a conversion function between a baseband signal and a bit stream according to the physical layer specifications of the system. For example, when transmitting data, the baseband processing unit (2-20) can generate complex symbols by encoding and modulating a transmission bit stream. In addition, when receiving data, the baseband processing unit (2-20) can restore a reception bit stream by demodulating and decoding a baseband signal provided from the RF processing unit (2-10). For example, in the case of following the OFDM (orthogonal frequency division multiplexing) method, when transmitting data, the baseband processing unit (2-20) can generate complex symbols by encoding and modulating a transmission bit stream, map the complex symbols to subcarriers, and then configure OFDM symbols by performing an IFFT (inverse fast Fourier transform) operation and CP (cyclic prefix) insertion. In addition, when receiving data, the baseband processing unit (2-20) divides the baseband signal provided from the RF processing unit (2-10) into OFDM symbol units, restores signals mapped to subcarriers through an FFT (fast Fourier transform) operation, and then restores the received bit string through demodulation and decoding.

The baseband processing unit (2-20) and the RF processing unit (2-10) can transmit and receive signals as described above. 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. Furthermore, at least one of the baseband processing unit (2-20) and the RF processing unit (2-10) may include a plurality of communication modules to support a plurality of different wireless access technologies. In addition, at least one of the baseband processing unit (2-20) and the RF processing unit (2-10) may include different communication modules to process signals of different frequency bands. For example, the different wireless access technologies may include a wireless LAN (e.g., IEEE 802.11), a cellular network (e.g., LTE), etc. In addition, the different frequency bands may include a super high frequency (SHF) (e.g., 2.NRHz, NRhz) band, a millimeter wave (mm wave) (e.g., 60GHz) band. The terminal may transmit and receive signals with the base station using the baseband processing unit (2-20) and the RF processing unit (2-10), and the signals may include control information and data.

The storage unit (2-30) can store data such as basic programs, application programs, and setting information for the operation of the terminal. In particular, the storage unit (2-30) can store information related to a second access node that performs wireless communication using the second wireless access technology. In addition, the storage unit (2-30) can provide the stored data according to a request from the control unit (2-40). In addition, the storage unit (2-30) can be composed of a plurality of memories. According to one embodiment, the storage unit (2-30) can store a program for performing the split bearer operation method of the present disclosure.

The control unit (2-40) can control the overall operations of the terminal. For example, the control unit (2-40) can transmit and receive signals through the baseband processing unit (2-20) and the RF processing unit (2-10). In addition, the control unit (2-40) can record and read data in the storage unit (2-40). To this end, the control unit (2-40) can include at least one processor. For example, the control unit (2-40) can include a CP (communication processor) that performs control for communication and an AP (application processor) that controls upper layers such as application programs. In addition, at least one component in the terminal can be implemented as one chip. In addition, according to one embodiment of the present disclosure, the control unit (2-40) can include a multi-connection processing unit (2-42) that performs processing for operating in a multi-connection mode.

FIG. 3 is a block diagram showing the configuration of a base station according to one embodiment of the present disclosure.

Referring to FIG. 3, the base station 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 control unit (3-50). Of course, it is not limited to the above example, and the base station may include fewer or more components than the configuration illustrated in FIG. 3.

The RF processing unit (3-10) can perform functions for transmitting and receiving signals through a wireless channel, such as signal band conversion and amplification. That is, the RF processing unit (3-10) can up-convert a baseband signal provided from the baseband processing unit (3-20) into an RF band signal and transmit it through an antenna, and down-convert an RF band signal received through the antenna into a baseband signal. For example, the RF processing unit (3-10) can include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, etc. In Fig. 3, only one antenna is illustrated, but the base station can have multiple antennas. In addition, the RF processing unit (3-10) can include multiple RF chains. Furthermore, the RF processing unit (3-10) can perform beamforming. For beamforming, the RF processing unit (3-10) can adjust the phase and size of each of the signals transmitted and received through multiple antennas or antenna elements. The RF processing unit (3-10) can perform a downward MIMO operation by transmitting one or more layers. The RF processing unit (3-10) can perform reception beam sweeping by appropriately setting a plurality of antennas or antenna elements under the control of the control unit, or can adjust the direction and beam width of the reception beam so that the reception beam is coordinated with the transmission beam.

The baseband processing unit (3-20) can perform a conversion function between a baseband signal and a bit stream according to the physical layer specifications of the first wireless access technology. For example, when transmitting data, the baseband processing unit (3-20) can generate complex symbols by encoding and modulating a transmission bit stream. In addition, when receiving data, the baseband processing unit (3-20) can restore a reception bit stream by demodulating and decoding a baseband signal provided from the RF processing unit (3-10). For example, in the case of following the OFDM method, when transmitting data, the baseband processing unit (3-20) can generate complex symbols by encoding and modulating a transmission bit stream, map the complex symbols to subcarriers, and then configure OFDM symbols through an IFFT operation and CP insertion. In addition, when receiving data, the baseband processing unit (3-20) can divide the baseband signal provided from the RF processing unit (3-10) into OFDM symbol units, restore the signals mapped to subcarriers through FFT operation, and then restore the received bit stream through demodulation and decoding. The baseband processing unit (3-20) and the RF processing unit (3-10) can transmit and receive signals as described above. Accordingly, the baseband processing unit (3-20) and the RF processing unit (3-10) can be referred to as a transmitter, a receiver, a transceiver, a communication unit, or a wireless communication unit. The base station can transmit and receive signals with the terminal using the baseband processing unit (3-20) and the RF processing unit (3-10), and the signals can include control information and data.

The backhaul communication unit (3-30) can provide an interface for performing communication with other nodes within the network. That is, the backhaul communication unit (3-30) can convert a bit string transmitted from a main base station to another node, such as an auxiliary base station or core network, into a physical signal, and can convert a physical signal received from another node into a bit string.

The storage unit (3-40) can store data such as basic programs, application programs, and setting information for the operation of the base station. In particular, the storage unit (3-40) can store information on bearers allocated to connected terminals, measurement results reported from connected terminals, and the like. In addition, the storage unit (3-40) can store information that serves as a judgment criterion for whether to provide or terminate multiple connections to the terminal. In addition, the storage unit (3-40) can provide stored data according to a request from the control unit (3-50). The storage unit (3-40) can also store a program for performing the split bearer operation method of the present disclosure.

The control unit (3-50) can control the overall operations of the base station. For example, the control unit (3-50) can transmit and 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 control unit (3-50) can record and read data in the storage unit (3-40). For this purpose, the control unit (3-50) can include at least one processor. In addition, at least one component of the base station can be implemented with one chip. In addition, at least one component of the base station can be implemented with one chip. In addition, each component of the base station can operate to perform the embodiments of the present disclosure described above.

The methods according to the embodiments described in the claims or specification of the present disclosure may be implemented in the form of hardware, software, or a combination of hardware and software.

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

These programs (software modules, software) may be stored in a random access memory, a non-volatile memory including a flash memory, a ROM (Read Only Memory), an Electrically Erasable Programmable Read Only Memory (EEPROM), a magnetic disc storage device, a Compact Disc-ROM (CD-ROM), a Digital Versatile Discs (DVDs) or other forms of optical storage devices, a magnetic cassette. Or, they may be stored in a memory composed of a combination of some or all of these. In addition, each configuration memory may be included in multiple numbers.

Additionally, the program may be stored in an attachable storage device that is accessible via a communication network, such as the Internet, an Intranet, a Local Area Network (LAN), a Wide LAN (WLAN), or a Storage Area Network (SAN), or a combination thereof. The storage device may be connected to a device performing an embodiment of the present disclosure via an external port. Additionally, a separate storage device on the communication network may be connected to a device performing an embodiment of the present disclosure.

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

Meanwhile, although the detailed description of the present disclosure has described specific embodiments, it is obvious that various modifications are possible within the scope of the present disclosure. Therefore, the scope of the present disclosure should not be limited to the described embodiments, but should be determined not only by the scope of the claims described below, but also by equivalents of the scope of the claims.

Claims (1)

In a method for processing a control signal in a wireless communication system,
A step of receiving a first control signal transmitted from a base station;
a step of processing the received first control signal; and
A control signal processing method, characterized by comprising a step of transmitting a second control signal generated based on the above processing to the base station.

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