KR20240127200A - Method and apparatus for handling xr traffic with different importance in wireless communication system - Google Patents

Abstract

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

Description

{METHOD AND APPARATUS FOR HANDLING XR TRAFFIC WITH DIFFERENT IMPORTANCE IN WIRELESS COMMUNICATION SYSTEM}

The present disclosure relates to a wireless communication system (or a mobile communication system). Specifically, the present disclosure relates to operations of a terminal and a base station in a wireless communication system (or a mobile communication system), and more particularly, to a method and device for servicing XR (extended reality) traffic with different priorities.

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, in the case of 6G mobile communication technology, which is called the system after 5G communication (Beyond 5G), implementation in the terahertz (THz) band (for example, 3 THz band at 95GHz) is being considered to achieve a transmission speed that is 50 times faster than 5G mobile communication technology and an ultra-low delay time that is reduced to 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), including 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, taking into account 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 vehicle's own 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, AI service support, metaverse service support, drone communications, etc. using eXtended Reality (XR), Artificial Intelligence (AI), and Machine Learning (ML) to efficiently support Augmented Reality (AR), Virtual Reality (VR), and Mixed Reality (MR).

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 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 frequency efficiency and system network of 6G mobile communication technology, satellite, AI (Artificial Intelligence) from the design stage and AI-based communication technology that implements end-to-end AI support functions to realize system optimization, and ultra-high-performance communication and computing resources to provide services with 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.

Meanwhile, with the development of communication systems, the demand for efficient provision of XR services is increasing day by day.

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

A method performed by a terminal according to one embodiment of the present disclosure comprises the steps of: receiving a first control signal transmitted from a base station; processing the received first control signal; and transmitting a second control signal generated based on the processing to the base station.

According to various embodiments of the present disclosure, XR traffic and XR services can be effectively provided 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 a protocol layer structure for servicing PDU sets with different importance levels according to one embodiment of the present disclosure.
FIG. 1e illustrates an example of a priority-based buffer status report (BSR) triggering operation of a logical channel (LCH) according to one embodiment of the present disclosure.
FIG. 1f illustrates an example of importance-based BSR triggering operation of a PDU set according to one embodiment of the present disclosure.
FIG. 1ga and FIG. 1gb illustrate examples of LCP (Logical Channel Prioritization) operation that considers both priority of LCH and importance of PDU set according to one embodiment of the present disclosure.
FIG. 1h illustrates a split bearer configuration according to an embodiment of the present disclosure.
FIG. 1i illustrates an example of a packet transmission operation when setting up a DRB (Data Radio Bearer) unit split bearer operation according to one embodiment of the present disclosure.
FIG. 1j illustrates an example of a packet transmission operation when setting a split bearer operation of an importance unit of a PDU set according to one embodiment of the present disclosure.
FIG. 1k illustrates a signaling procedure between a terminal and a base station for setting and operating terminal operations based on PDU set importance in a next-generation mobile communication system according to an embodiment of the present disclosure.
FIG. 1l illustrates a MAC (medium access control) CE (control element) structure that can be used to enable/disable PDCP (packet data convergence protocol) duplication in units of importance of a PDU set according to one embodiment of the present disclosure.
FIG. 1m illustrates a terminal device according to one embodiment of the present disclosure.
FIG. 1n 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 disclosure will be described with reference to the attached drawings.

For the same reason, some components in the attached drawings are exaggerated, omitted, or schematically illustrated. In addition, the size of each component does not entirely reflect the actual size. The same or corresponding components in each drawing are given the same reference numbers.

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 a person having ordinary skill in the art to which the present disclosure belongs of the scope of the disclosure, 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 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, 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 (medium 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 one 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/km^2) 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 may require wider coverage than 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)) is composed of a next-generation base station (New Radio Node B, hereinafter, gNB) (1a-10) and an access and mobility management function (AMF, 1a-05). 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 maximum bandwidth greater than the existing one, and additionally beamforming technology may be used with orthogonal frequency division multiplexing (OFDM) as a wireless access technology.

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 linked with the existing LTE system, and AMF (1a-05) is connected to MME (mobility management function, 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. The 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., an RRC (radio resource control) layer).

According to one embodiment of the present disclosure, PDCP (1b-15)(1b-20) may perform operations such as IP (internet protocol) header compression and/or restoration, and may additionally 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 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 downlink 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 additionally uses a primary component carrier and one or more secondary component carriers instead of only one 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 the 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 using the MPEG (moving picture experts group) standard video compression technology in video traffic, a PDU set can be composed of 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 or PDU sets, etc.) having different quality of service (QoS) requirements. Taking the MPEG described above as an 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}, for example. In the case of downlink data, the UPF (user plane function) can include the importance information in the GTP-U (GPRS (General Packet Radio Service) Tunnelling Protocol - user plane) header, and the base station can consider the importance when transmitting the PDU set in the downlink. In addition, in the case of the uplink, the importance information can be transmitted from the application layer of the terminal to the 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 at this time, the importance of the data can be ultimately determined by the importance of the PDU set that the data constitutes.

In the embodiments of the present disclosure below, it is explained on the premise that a lower importance value of a PDU set indicates a higher importance, but 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.

FIG. 1d illustrates a protocol layer structure for servicing PDU sets with different importance levels according to one embodiment of the present disclosure.

Referring to Fig. 1d, the PDU sets constituting the XR traffic flow may have different priorities. In order to service the PDU sets with different priorities, various protocol hierarchies as follows may be considered.

- Structure 1 (1d-01): When PDU sets (1d-02 and 1d-03) with different importance have different QoS requirements, the PDU sets (1d-02 and 1d-03) can be transmitted through different QoS flows (1d-04 and 1d-05). The QoS flows can be transmitted through different DRBs (1d-06 and 1d-07) to satisfy different QoS requirements. In addition, the DRBs can be mapped to different LCHs (1d-08 and 1d-09) to satisfy different QoS requirements. In the current specification, each LCH can have a different priority. In addition, the priority of each LCH can be used for scheduling related operations performed in the MAC layer (e.g., LCP and BSR triggering operations). Therefore, PDU sets transmitted through different LCHs can be scheduled with different priorities. In the above structure (1d-01), PDU sets (1d-02 and 1d-03) with different importance can be scheduled with different priorities by being transmitted through different QoS flows, different DRBs, and different LCHs.

However, when the above-described structure 1 (1d-01) is used, in-order delivery may not be guaranteed for PDU sets constituting the same XR traffic flow. For reference, in-order delivery may be guaranteed for packets transmitted through the same DRB. To this end, the transmitting PDCP layer of each DRB sequentially attaches a PDCP SN (sequence number) to data received from the upper layer, includes the data in the PDCP header, and transmits the data, and the receiving PDCP layer sequentially transmits the data to the upper layer based on the PDCP SN. In the above structure (1d-01), since the PDU sets constituting the XR traffic flow are mapped to different QoS flows according to importance and transmitted again through different DRBs, the order between the PDU sets may be changed during data transmission, so in-order delivery cannot be guaranteed.

- Structure 2 (1d-10): If PDU sets (1d-11 and 1d-12) with different importance have the same QoS requirements, the PDU sets (1d-11 and 1d-12) can be transmitted through the same QoS flow (1d-13). The QoS flow can be mapped to one DRB (1d-15). In this case, the sequential transmission for the PDU sets constituting the XR traffic flow can be guaranteed due to the sequential transmission function provided in the PDCP layer of the DRB (1d-15).

The above DRB can be mapped to different LCHs (1d-17 and 1d-19) to process PDU sets (1d-11, 1d-12) with different importance differently according to their importance. According to the current specification, each LCH can have a different priority, and the priority of each LCH can be used for scheduling-related operations (e.g., LCP and BSR triggering operations) performed in the MAC layer. Therefore, PDU sets transmitted through different LCHs according to their importance can be eventually scheduled with different priorities. In the above structure (1d-10), PDU sets (1d-11 and 1d-12) with different importance can be scheduled with different priorities by being transmitted through different LCHs. In order to transmit PDU sets through different LCHs according to their importance within the same DRB as in the above method, an improvement in the DRB configuration method is required. The following Examples 1i, 1j, and 1k of the present disclosure specifically describe a method for supporting the above-described structure 2 (1d-10).

In order to use the above structure 2 (1d-10), the base station must already know in advance information about which PDU sets have which priorities to be transmitted through the QoS flow at the stage of setting the DRB mapped to a specific QoS flow to the terminal. In other words, the CN (core network) must be able to inform the base station in advance information about the importance of the PDU sets to be transmitted through the QoS flow for each QoS flow. If not, the base station cannot know the importance of the PDU sets to be transmitted from the QoS flow mapped to the DRB at the stage of setting the DRB to the terminal. Therefore, the base station must create separate LCH settings for all possible importance values (e.g., values from 0 to 8) and map them to the DRB.

- Structure 3 (1d-20): If PDU sets (1d-21 and 1d-22) with different importance levels have the same QoS requirements, the PDU sets (1d-21 and 1d-22) can be transmitted through the same QoS flow (1d-23). The QoS flow (1d-23) can be mapped to one DRB (1d-25). In this case, the sequential transmission for the PDU sets constituting the XR traffic flow can be guaranteed due to the sequential transmission function provided by the PDCP layer of the DRB.

Again, the above DRB (1d-25) can be mapped to one LCH (1d-27). If the CN cannot inform the base station in advance of the importance information of the PDU set to be transmitted through the QoS flow, the base station can set the LCH by referring only to the QoS requirements of the QoS flow mapped to the DRB and map the LCH to the DRB.

However, in this case, when PDU sets having different importance are transmitted through the QoS flow, the PDU sets are mapped to the same LCH and thus are processed at the MAC layer with the same priority. For reference, since scheduling-related operations (e.g., LCP and BSR triggering operations) performed at the MAC layer according to the current standard are performed based on the priority of the LCH, data transmitted through the same LCH is serviced at the MAC layer with the same priority. Therefore, when the structure 3 (1d-20) is used, PDU sets having different importance may not be serviced differently according to the current MAC standard operation. Therefore, the present disclosure proposes a method for improving scheduling-related operations (e.g., LCP and BSR triggering operations) performed at the MAC layer so that PDU sets having different importance can be processed at the MAC layer with different priorities, through the embodiments of FIGS. 1e, 1f, 1ga, and 1gb. More specifically, we propose a method in which the importance of an RLC PDU (i.e., the importance of the PDU set composed of the data included in the corresponding RLC PDU) can be considered together with the priority of the LCH in MAC layer operations (LCP and BSR triggering operations).

FIG. 1e illustrates an example of a priority-based BSR triggering operation of a logical channel (LCH) according to one embodiment of the present disclosure.

Referring to the above drawing 1e, when UL data to be transmitted arrives in the buffer, the MAC layer of the terminal can trigger Regular BSR (Regular Buffer Status Report) transmission to notify the base station of the existence of the corresponding UL data. The BSR transmitted by the terminal can include the amount of UL data currently buffered in units of Logical Channel Groups (LCGs) that group logical channels. The base station that receives the BSR from the terminal can allocate a UL grant (or radio resources required for uplink transmission) to the terminal based on the information included in the BSR. The MAC layer of the terminal can determine whether to trigger the BSR by considering the priority of the logical channel on which the corresponding UL data arrived in order to reduce the load that occurs when triggering the Regular BSR every time new UL data arrives in the buffer. More specifically, the MAC layer can trigger the Regular BSR when new UL data arrives and at least one of the following two conditions is satisfied.

- Condition 1: When UL data arrives on a logical channel that has a higher priority than any logical channel that already has UL data available for transmission.

For example, in Example 1 (1e-10), when new UL data (1e-11) arrives in LCH A (or the buffer of LCH A), the UE can trigger regular BSR because LCH A (with priority 1) has higher priority than LCH B (with priority 2) and LCH D (with priority 3), which already have transmittable UL data (1e-12 and 1e-14).

- Condition 2: If there is no other logical channel that already has UL data that can be transmitted in the LCG to which the logical channel to which the UL data arrived belongs.

For example, in case new UL data (1e-21) arrives in LCH B (or the buffer of LCH B) as in Example 2 (1e-20), the UE can trigger regular BSR because there is no other logical channel having transmittable UL data in LCG 1 (1e-22) to which LCH B belongs (in other words, there is no transmittable UL data in LCH A). In this case, even though there is LCH C having transmittable UL data (1e-23) in another LCG2 (1e-24) to which LCH B does not belong and the priority of LCH C (with priority 1) is higher than that of LCH B (with priority 2), the UE can trigger regular BSR to inform the presence of newly arrived UL data in LCG1.

Through the operation corresponding to condition 1 among the two conditions above, when UL data arrives on a logical channel with high priority, the terminal can request the base station for UL grant resources for transmitting the UL data. In this case, the priority of the newly arrived UL data is determined only by the priority of the logical channel on which the UL data arrived. However, as described for structure 3 (1d-20) of the above Fig. 1d, the PDU sets constituting the XR traffic flow can have different importances and be mapped to the same QoS flow, the same DRB, and the same LCH and transmitted. In this case, PDU sets with different importances can be mapped to the same LCH. In this case, since the regular BSR triggering conditions are designed by considering only the priority of the LCH, even if UL data with higher importance than the UL data currently waiting for transmission arrives on a specific LCH, the regular BSR cannot be triggered. For example, as in Example 3 (1e-30), UL data with different importance levels may be mapped and arrive at LCH A. At this time, if new UL data (1e-31) with importance level 2 arrives, regular BSR cannot be triggered because Conditions 1 and 2 are not satisfied even though the UL data has a higher importance level than other UL data (1e-32) with importance level 3 that were previously waiting to be transmitted on LCH A.

More specifically, looking at whether Condition 2 is satisfied, since there is already an LCH B with transmittable UL data (1e-33) in LCG 1 to which LCH A belongs, the UL data (1e-31) newly arrived on LCH A cannot trigger regular BSR. In addition, looking at whether Condition 1 is satisfied, the highest priority among the priorities of the logical channels (LCH A, LCH B, LCH D) that already have transmittable UL data (1e-32, 1e-33, 1e-36) is 1, and the priority of LCH A to which the newly arrived UL data belongs is also (not high) 1, so the newly arrived UL data (1e-31) cannot trigger regular BSR. Therefore, the two conditions above, which only consider the priorities of logical channels, cannot process UL data with different priorities differently according to their priorities.

Therefore, in this disclosure, we propose a method to improve the conditions for triggering regular BSR in the MAC layer so that different PDU sets constituting an XR traffic flow can be processed differently according to their importance even when mapped to the same LCH.

For reference, UL data in the MAC layer can mean RLC PDU (or MAC SDU (service data unit)). In addition, the importance of the UL data here can mean the importance of the PDU set composed of the corresponding UL data (RLC PDU), and the corresponding importance can be determined in the application layer of the terminal and transmitted to the MAC layer. In addition, the present embodiment was written assuming that a lower importance value indicates a higher importance for ease of explanation, but the method described in the embodiments of the present disclosure can also be applied in cases where a higher importance value indicates a higher importance, or where the importance values are given as {true, false}, etc. and the 'true' value indicates a higher importance than the 'false' value.

FIG. 1f illustrates an example of importance-based BSR triggering operation of a PDU set according to one embodiment of the present disclosure.

Referring to Fig. 1f, when UL data to be transmitted arrives, the MAC layer of the terminal can trigger Regular BSR transmission to notify the base station of the existence of the corresponding UL data. At this time, not only the priority of the LCH where the corresponding UL data arrived for the Regular BSR triggering condition but also the importance of the corresponding UL data can be considered. For this, two methods can be considered.

- Method 1 (1f-10): If newly arrived UL data has higher importance than any UL data that could be transmitted (or was waiting to be transmitted) previously, the MAC layer of the terminal may trigger regular BSR. In this regard, the method may be applied only when an indicator (e.g., BSRbasedOnImportance) is set in the configuration information for MAC operation of the terminal (e.g., MAC-CellGroupConfig) to instruct to perform BSR triggering based on the importance of a PDU set. The operation can be expressed as shown in Table 1 below.

[Table 1]

More specifically, if new UL data (1f-12) arrives at LCH A as in Example 1 (1f-11), the UL data (with importance 1) has a higher importance than any of the UL data (1f-13, 1f-14, 1f-15, 1f-16) that were previously transmittable (or queued for transmission). Therefore, the MAC layer of the terminal can trigger regular BSR. On the other hand, if there is data (1f-18) among the UL data (queued for transmission) that has a higher or equal importance than the newly arrived UL data as in Example 2 (1f-19), the MAC layer of the terminal cannot trigger regular BSR.

According to the above method 1 (1f-10), the importance of UL data is considered separately regardless of the priority of the logical channel under regular BSR triggering conditions. Therefore, if the importance of newly arrived UL data is higher than the importance of UL data that were previously waiting, the terminal can trigger regular BSR, and the base station can allocate a new UL grant (uplink transmission resource) to the terminal by considering the data with high importance based on the BSR.

Method 2 (1f-20): If UL data arrives on a logical channel having the highest priority among any logical channels that already have transmittable UL data and has higher importance than other UL data belonging to the logical channels having the corresponding priority, the MAC layer of the terminal may trigger regular BSR. Additionally, the method may be applied only when a directive (e.g., BSRbasedOnImportance) is set in the MAC operation configuration of the terminal (e.g., MAC-CellGroupConfig) to instruct to perform BSR triggering based on importance of a PDU set. The operation may be expressed as shown in Table 2 below.

[Table 2]

More specifically, a case where new UL data (1f-22) arrives at LCH A as in Example 1 (1f-21) is described. In Example 1 (1f-21), if the UL data (1f-22) arrives at a logical channel (LCH A with priority 1 and LCH C with priority 1) having the highest priority among any logical channels (LCH A, LCH B, LCH C, LCH D) that already have transmittable UL data, and the newly arrived UL data (1f-22 with importance 1) has a higher importance than other UL data (1f-23 with importance 3 and 1f-24 with importance 2) belonging to the logical channels (LCH A and LCH C) with the corresponding priorities, the MAC layer of the terminal may trigger regular BSR.

On the other hand, if new UL data (1f-25) arrives on LCH B as in Example 2 (1f-25), and the LCH B with priority 2 on which the UL data (1f-25) arrives has a lower priority (priority 2) than the highest priority (Priority 1) among any of the priorities of logical channels (LCH A, LCH B, LCH C, LCH D) that already have transmittable UL data, the MAC layer of the terminal cannot trigger regular BSR.

Also, when new UL data (1f-26) arrives at LCH A as in Example 3 (1f-28), the UL data (1f-26) arrives at the logical channel (LCH A with priority 1) having the highest priority among any logical channels (LCH A, LCH B, LCH C, LCH D) that already have transmittable UL data. However, since the newly arrived UL data (1f-26 with importance 2) has the same importance as other UL data (1f-27 with importance 2) belonging to the logical channels (LCH A and LCH C) with the corresponding priorities, the MAC layer of the terminal cannot trigger regular BSR.

According to the above method 2 (1f-20), in the regular BSR triggering condition, the priority of the logical channel is considered first as before, but the importance of UL data is considered separately again within the logical channels with the highest priority. Therefore, if the importance of newly arrived UL data is higher than the importance of the UL data that were previously waiting, the terminal can trigger the regular BSR, and the base station can consider the data with high importance based on the BSR and allocate a new UL grant (uplink transmission resource) to the terminal.

For reference, UL data in the MAC layer can mean RLC PDU (or MAC SDU). In addition, the importance of UL data can mean the importance of the PDU set composed of the corresponding UL data (RLC PDU), and the importance can be determined in the application layer of the terminal and transmitted to the MAC layer. In addition, the present embodiment was written assuming that a lower importance value means a higher importance for ease of explanation, but the method described in the embodiments of the present disclosure can also be applied in cases where a higher importance value means a higher importance, or where the importance values are given as {true, false}, etc. and the 'true' value means a higher importance than the 'false' value.

FIGS. 1ga and 1gb illustrate examples of LCP (Logical Channel Prioritization) operation that considers both priority of LCH and importance of PDU set according to one embodiment of the present disclosure.

Referring to FIGS. 1ga and 1gb, when a terminal is allocated a UL grant from a base station, the terminal can calculate the size of uplink data (Transport Block (TB) size or MAC PDU size) (1g-02) that can be transmitted using the UL grant. Thereafter, the MAC layer of the terminal can perform an LCP (Logical Channel Prioritization) operation to determine in which order to fill UL data (1g-03, 1g-04, 1g-05) waiting for transmission in each LCH into MAC PDUs of the calculated size (in other words, to determine in which order to allocate uplink transmission resources to each logical channel). More specifically, the LCP operation performed in the MAC layer can be performed in one of the following manners.

- Mode 0 (1g-01): The MAC layer can perform LCP by considering only the priority of the logical channel. The LCP operation considering only the logical channel can be expressed as shown in Table 3 below.

[Table 3]

In the above operation, the Bj value is a value calculated for each LCH in the stage before performing LCP, and can be calculated based on the PBR (Prioritized Bit Rate) value that is set separately for each LCH. At this time, the Bj value can be understood as the size of the uplink transmission resource expected to be allocated to each LCH (in other words, the size of the MAC SDU expected to be provided to each LCH).

The process of performing LCP in the above manner can be described more specifically through an example (1g-01). In this example, it is assumed that LCH A, LCH B, and LCH C are set as logical channels to be LCP performed in a step prior to performing LCP. At this time, LCH A is a logical channel to which XR traffic is not mapped (in other words, a PDU set with high importance is not mapped), and only UL data (RLC PDU or MAC SDU) that is not assigned a specific importance value can exist in LCH A. The MAC layer of the terminal can allocate uplink transmission resources to logical channels (LCH A, LCH B, LCH C) for which the Bj value is calculated to be greater than 0. For reference, in this embodiment, the Bj values (Bj_a, Bj_b, Bj_c) of each LCH are expressed to be the same, but in reality, the corresponding values may be calculated differently for each LCH. The above transmission resource allocation can be performed in the descending order of the priorities of each LCH, and when the priorities of the LCHs are the same, the resource allocation priority can be determined according to the terminal implementation. In this example, although the priority values of LCH A and LCH B are the same (1), resource allocation can be performed first for LCH A in the order in which the LCHs are set by the terminal implementation, and then resource allocation can be performed in the order of LCH B and LCH C. More specifically, resource allocation can be performed Bj_a for UL data (1g-03) waiting for LCH A first. Afterwards, since there is more space left on the MAC PDU, resource allocation can be performed for UL data (1g-04) waiting for LCH B. However, in this example, after performing resource allocation for UL data with importance 3 among the UL data (1g-04) waiting in LCH B (in other words, after including UL data with importance 3 in the MAC PDU), there are no resources left, so the LCP operation ends.

If LCP is performed by considering only the priority of the logical channel as in the above example (1g-01), UL data with relatively high importance (in other words, UL data belonging to LCH B and LCH C and having relatively high importance 2 or 3) may be pushed down in the LCP process and may experience high delay time. Therefore, in this disclosure, we propose the following LCP methods that can consider not only the priority of the logical channel but also the importance of UL data.

- Method 1 (1g-10): The MAC layer performs LCP by giving priority to the priority of the Logical channel, and for Logical channels with the same priority, the importance of UL data waiting for each logical channel may be considered together. In addition, the MAC layer of the terminal may apply the above method only when it is set to consider the importance of UL data in scheduling-related operations (more specifically, when the 'SchedulingBasedonImportance' indicator is set to the terminal by RRC settings). The LCP operation can be expressed as shown in Table 4 below.

[Table 4]

In the above operation, the Bj value is a value calculated for each LCH in the stage before performing LCP, and can be calculated based on the PBR (Prioritized Bit Rate) value that is set separately for each LCH. At this time, the Bj value can be understood as the size of the uplink transmission resource expected to be allocated to each LCH (in other words, the size of the MAC SDU expected to be provided to each LCH).

The process of performing LCP in the above manner can be described more specifically through an example (1g-10). In this example, it is assumed that LCH A, LCH B, and LCH C are set as logical channels to be LCP performed in a step prior to performing LCP. At this time, LCH A is a logical channel to which XR traffic is not mapped (in other words, a PDU set with importance is not mapped), and only UL data (RLC PDU or MAC SDU) that is not assigned a specific importance value can exist in LCH A. The MAC layer of the terminal can allocate uplink transmission resources to logical channels (LCH A, LCH B, LCH C) for which the Bj value is calculated to be greater than 0. For reference, in this embodiment, the Bj values (Bj_a, Bj_b, Bj_c) of each LCH are expressed equally, but in reality, the corresponding values may be calculated differently for each LCH.

The above transmission resource allocation can be performed in the descending order of the priority of each LCH, and the transmission resources can be allocated in the descending order of the importance of each LCH for LCHs with the same priority. For reference, as in the present example (1g-10), the importance of each LCH can be determined according to the importance of UL data waiting in the corresponding LCH. For example, the importance of a specific LCH can be determined as the importance value of UL data with the highest importance among the UL data waiting in the corresponding LCH. For example, in the present example (1g-10), the importance of LCH B can be determined as 2 and the importance of LCH C can be determined as 1. In addition, if the importance values of the PDU set to be transmitted through the corresponding LCH are set in advance for each LCH by RRC signaling, the importance value indicating the highest importance among them can be determined as the importance value of the corresponding LCH.

On the other hand, for an LCH that does not include UL data with importance, such as LCH A (or when the DRB connected to the LCH A is not configured to handle the Importance of the PDU set), the LCH may be specified in the specification to have the lowest importance value or an arbitrary importance value. Alternatively, the importance value of the LCH that does not include UL data with importance, such as LCH A, may be separately configured to the UE through RRC signaling. In this example, it is assumed that LCH A that does not include UL data with importance has the lowest importance, and it is assumed that the importance value of the LCH B and LCH C that include UL data with importance is determined as the importance value of the UL data with the highest importance among the UL data waiting in the LCH. That is, in this embodiment, the importance value of LCH B is 2, and the importance value of LCH C is 1.

In this example (1g-10), the priority values of LCH A and LCH B are the same (1), but since the importance of LCH B is 2 and the importance of LCH A is the lowest, resource allocation is performed first for LCH B in descending order of importance, and then resource allocation can be performed in the order of LCH A and LCH C. More specifically, resource allocation Bj_b can be performed for UL data (1g-12) waiting in LCH B first. Afterwards, resource allocation can be performed for UL data (1g-11) waiting in LCH A because there is more space remaining in the MAC PDU. However, in this example, after resource allocation is performed for UL data (1g-11) waiting in LCH A, the LCP operation ends because there are no resources remaining.

As in the above example (1g-10), when the priority values of logical channels are the same, if LCP is performed by additionally considering the importance value of each logical channel, UL data with relatively high importance (in other words, UL data belonging to LCH B and having relatively high importance 2 or 3) among logical channels with the same priority value can have priority in the LCP process. However, resource allocation for UL data (1g-05) belonging to LCH C with low priority is pushed down and may experience high delay time. Therefore, in this disclosure, we would like to additionally propose the following LCP methods that can first consider the importance of UL data included in each LCH before comparing the priorities of logical channels.

- Method 2-1 (1g-20): The MAC layer may preferentially allocate resources to LCHs in which UL data having importance exists, and then perform resource allocation for the remaining resources in the same manner as in Method 1. Additionally, the MAC layer of the terminal may apply the method only when it is set to consider the importance of UL data in scheduling-related operations (more specifically, when the 'SchedulingBasedonImportance' indicator is set to the terminal by RRC settings). The LCP operation can be expressed as shown in Table 5 below.

[Table 5]

In the above operation, the Bj value is a value calculated for each LCH in the stage before performing LCP, and can be calculated based on the PBR (Prioritized Bit Rate) value that is set separately for each LCH. At this time, the Bj value can be understood as the size of the uplink transmission resource expected to be allocated to each LCH (in other words, the size of the MAC SDU expected to be provided to each LCH).

The process of performing LCP according to the above method 2-1 can be described more specifically through an example (1g-20). In this example, it is assumed that LCH A, LCH B, and LCH C are set as logical channels to be LCP performed in a step prior to performing LCP. At this time, LCH A is a logical channel to which XR traffic is not mapped (in other words, a PDU set with importance is not mapped), and only UL data (RLC PDU or MAC SDU) that is not assigned a specific importance value can exist in LCH A. The MAC layer of the terminal can allocate uplink transmission resources to logical channels (LCH A, LCH B, LCH C) for which the Bj value is calculated to be greater than 0.

The above transmission resource allocation is performed preferentially for LCHs in which UL data having importance exists, and at this time, resource allocation can be performed in descending order of priority of each LCH, and for LCHs with the same priority, transmission resources can be allocated in descending order of importance of each LCH. As a reference, the method in which the importance of each LCH is determined as in this example can be applied identically or similarly to the method 1 (1g-10) described above.

In this example (1g-20), resource allocation may be performed first for LCH B and LCH C including UL data having importance as in step 1 of Table 5 above. At this time, since the priority of LCH B (with priority 1) is higher than that of LCH C (with priority 2), resource allocation may be performed first for LCH B in the descending order of LCH priorities, and then for LCH C. Specifically, resource allocation Bj_b may be performed first for UL data (1g-22) waiting for LCH B. Afterwards, since there is more space left on the MAC PDU, resource allocation may be performed for UL data (1g-23) waiting for LCH C (1g-24). In addition, the Bj values (Bj_a and Bj_c) of LCH B and LCH C may be updated to 0.

Afterwards, it proceeds to step 2 of the above Table 5, and resource allocation can be performed in the same manner as described in the above method 1 (1g-10). First, since LCH A is the only LCH left with a Bj value greater than 0, resource allocation for LCH A can be performed (1g-25). Afterwards, the Bj value (Bj_a) of LCH A can be updated to 0.

Afterwards, the resource allocation can be performed in the descending order of priority of the LCHs by proceeding to Step 3 of Table 5 until the remaining UL grant resources are exhausted. In this example (1g-20), there is one UL data (e.g., RLC PDU or MAC SDU) remaining in LCH A and LCH C respectively, and since the priority (1) of LCH A is higher than the priority (2) of LCH C, resource allocation for LCH A is performed first (1g-26). Afterwards, the transmission of the UL data with importance 2 remaining in LCH C may be delayed because all MAC PDUs are full (i.e., all available UL grants are used).

- Method 2-2 (1g-30): Resources are preferentially allocated to LCHs in which UL data having an importance higher than a threshold (e.g., ThreImportance) set by the network exist, and resource allocation can be performed for the remaining resources in the same manner as in Method 1. Additionally, the MAC layer of the terminal may apply the method only when it is set to consider the importance of UL data in scheduling-related operations (more specifically, when the 'SchedulingBasedonImportance' indicator is set to the terminal by RRC configuration). In addition, the threshold (e.g., ThreImportance) can be set to the terminal through RRC signaling. The LCP operation can be expressed as in Table 6 below.

[Table 6]

In the above operation, the Bj value is a value calculated for each LCH in the stage before performing LCP, and can be calculated based on the PBR (Prioritized Bit Rate) value that is set separately for each LCH. At this time, the Bj value can be understood as the size of the uplink transmission resource expected to be allocated to each LCH (in other words, the size of the MAC SDU expected to be provided to each LCH).

The process of performing LCP in the above manner can be described more specifically through an example (1g-30). In this example, it is assumed that LCH A, LCH B, and LCH C are set as logical channels to be LCP-performed in a step prior to performing LCP. At this time, LCH A is a logical channel to which XR traffic is not mapped (in other words, a PDU set with importance is not mapped), and only UL data (RLC PDU or MAC SDU) that is not assigned a specific importance value can exist in LCH A. The MAC layer of the terminal can allocate uplink transmission resources to logical channels (LCH A, LCH B, LCH C) for which the Bj value is calculated to be greater than 0.

The above transmission resource allocation is performed preferentially for LCHs in which UL data having an importance higher than a specific threshold exists, and at this time, resource allocation can be performed in descending order of priority of each LCH, and for LCHs with the same priority, transmission resources can be allocated in descending order of importance of each LCH. For reference, the method by which the importance of each LCH is determined as in this example is as described in detail in Method 1 (1g-10).

In this example (1g-30), resource allocation may be performed first for LCH B (with importance 2) and LCH C (with importance 1) including UL data having an importance higher than a specific threshold (1g-32) set to 3 as in Step 1 of Table 6 above. At this time, since the priority of LCH B (with priority 1) is higher than that of LCH C (with priority 2), resource allocation may be performed first for LCH B in the descending order of LCH priorities, and then for LCH C. Specifically, resource allocation may be performed first for UL data (1g-34) waiting for LCH B as much as Bj_b. Afterwards, resource allocation may be performed for UL data (1g-35) waiting for LCH C because there is more space left on the MAC PDU (1g-36). And the Bj values (Bj_a and Bj_c) of LCH B and LCH C can be updated to 0.

Afterwards, it proceeds to step 2 of the above Table 6, and resource allocation can be performed in the same manner as described in the above method 1 (1g-10). First, since LCH A is the only LCH left with a Bj value greater than 0, resource allocation for LCH A can be performed (1g-37). Afterwards, the Bj value (Bj_a) of LCH A can be updated to 0.

Afterwards, the resource allocation can be performed in the descending order of priority of the LCHs by proceeding to Step 3 of Table 6 until the remaining UL grant resources are exhausted. In this example (1g-30), there is one UL data (e.g., RLC PDU or MAC SDU) remaining in LCH A and LCH C respectively, and since the priority (1) of LCH A is higher than the priority (2) of LCH C, resource allocation for LCH A is performed first (1g-38). Afterwards, the transmission of the UL data with importance 2 remaining in LCH C may be delayed because all MAC PDUs are full (i.e., all available UL grants are used).

On the other hand, if the threImportance value is set to 2 as in the example (1g-41), resource allocation can be performed first only for LCH C (with importance 1) including UL data with higher importance. Specifically, resource allocation can be performed for Bj_c for UL data (1g-45) waiting in LCH C (1g-46), and then the Bj_c value can be updated to 0.

Afterwards, it proceeds to step 2 of the above Table 6, and resource allocation can be performed in the same manner as described in the above method 1 (1g-10). First, LCH A and LCH B remain as LCHs having Bj values greater than 0, and since the priorities of the two LCHs are the same, resource allocation can be performed in the descending order of the importance of each LCH. In this case, since the importance (2) of LCH B is higher than that of LCH A (the lowest), resource allocation for LCH B can be performed as much as Bj_b, and then resource allocation for LCH A can be performed as much as Bj_a (1g-47). Afterwards, the Bj values (Bj_a and Bj_b) of LCH A and LCH B can be updated to 0.

Afterwards, the resource allocation can be performed in the descending order of priority of the LCHs by proceeding to Step 3 of Table 6 until the remaining UL grant resources are exhausted. In this example (1g-40), there is one UL data (e.g., RLC PDU or MAC SDU) remaining in LCH A and LCH C respectively, and since the priority (1) of LCH A is higher than the priority (2) of LCH C, resource allocation for LCH A is performed first (1g-48). Afterwards, the transmission of the UL data with importance 2 remaining in LCH C may be delayed because all MAC PDUs are full (i.e., all available UL grants are used).

- Method 2-3 (1g-50): The MAC layer preferentially allocates resources to LCHs that contain UL data with importance, and performs resource allocation in descending order of importance, not in order of priority of LCHs. Afterwards, resource allocation can be performed as in Method 1 for the remaining resources. In addition, the MAC layer of the terminal may apply the method only when it is set to consider the importance of UL data in scheduling-related operations (more specifically, when the 'SchedulingBasedonImportance' indicator is set for the terminal by RRC settings). The LCP operation can be expressed as in Table 7 below.

[Table 7]

In the above operation, the Bj value is a value calculated for each LCH in the stage before performing LCP, and can be calculated based on the PBR (Prioritized Bit Rate) value that is set separately for each LCH. At this time, the Bj value can be understood as the size of the uplink transmission resource expected to be allocated to each LCH (in other words, the size of the MAC SDU expected to be provided to each LCH).

The process of performing LCP in the above manner can be described more specifically through an example (1g-50). In this example, it is assumed that LCH A, LCH B, and LCH C are set as logical channels to be LCP performed in a step prior to performing LCP. At this time, LCH A is a logical channel to which XR traffic is not mapped (in other words, a PDU set with importance is not mapped), and only UL data (RLC PDU or MAC SDU) that is not assigned a specific importance value can exist in LCH A. The MAC layer of the terminal can allocate uplink transmission resources to logical channels (LCH A, LCH B, LCH C) for which the Bj value is calculated to be greater than 0.

The above transmission resource allocation is performed preferentially for LCHs in which UL data having importance exists, and at this time, resource allocation can be performed in the descending order of importance of each LCH, and for LCHs with the same importance, transmission resources can be allocated in the descending order of priority of each LCH. For reference, the method by which the importance of each LCH is determined as in this example is as described in detail in Method 1 (1g-10) above.

In this example, resource allocation may be performed first for LCH B and LCH C including UL data having importance as in Step 1 of Table 7 above. At this time, since the importance of LCH C (with importance 1) is higher than that of LCH B (with importance 2), resource allocation may be performed first for LCH C in descending order of importance, and then resource allocation may be performed for LCH B. Specifically, resource allocation may be performed first for UL data (1g-53) waiting for LCH C as much as Bj_c. Afterwards, resource allocation may be performed for UL data (1g-52) waiting for LCH B because there is more space left on the MAC PDU (1g-54). Then, the Bj values (Bj_a and Bj_c) of LCH B and LCH C may be updated to 0.

Afterwards, it proceeds to step 2 of the above Table 7, and resource allocation can be performed in the same manner as described in the above method 1 (1g-10). First, since LCH A is the only LCH left with a Bj value greater than 0, resource allocation for LCH A can be performed (1g-55). Afterwards, the Bj value (Bj_a) of LCH A can be updated to 0.

Afterwards, the resource allocation can be performed in the descending order of priority of the LCHs by proceeding to Step 3 of Table 7 until the remaining UL grant resources are exhausted. In the present example (1g-50), there is one UL data (e.g., RLC PDU or MAC SDU) remaining in LCH A and LCH C respectively, and since the priority (1) of LCH A is higher than the priority (2) of LCH C, resource allocation for LCH A is performed first. (1g-56) Afterwards, since all MAC PDUs are full (i.e., all available UL grants are allocated), transmission of the remaining UL data with importance 2 in LCH C may be delayed.

FIG. 1h illustrates a split bearer configuration according to an embodiment of the present disclosure.

Referring to Fig. 1h, the SDAP (1h-10) layer can map each QoS flow (1h-40) to a specific DRB. When one or more QoS flows exist, multiple QoS flows can be mapped to one DRB. In the present disclosure, a split bearer is defined as a DRB (1h-50) that transmits data using two or more RLC bearers (or RLC entities) (1h-30)(1h-31)(1h-32). In a dual connectivity scenario, RLC entities configured in different cell groups (e.g., master cell group (MCG) or secondary cell group (SCG)) can be mapped together to the same split bearer. Additionally, each RLC entity can be mapped to each logical channel again. There are two ways to utilize multiple RLC bearers when transmitting data through a split bearer.

1) Duplication operation: To increase reliability and safety when transmitting packets, the same packets are transmitted repeatedly through different RLC entities at the PDCP layer.

2) Split operation: To increase data throughput when transmitting packets, the PDCP layer transmits packets through one of the different RLC entities.

When a terminal transmits UL data through a Split bearer, a PDCP entity (1h-20) can be linked with multiple RLC entities to perform duplication and split operations according to the RRC settings. For this purpose, one primary path (or primary RLC entity) (1h-30) can be set for each Split bearer. If neither the duplication operation nor the split operation is activated, the packet can be transmitted through the primary path (1h-30). For the split operation, one split secondary path (or split secondary RLC entity) (1h-31) and ul-DataSplitThreshold can be set for each Split bearer. The PDCP layer can forward the packet (PDCP PDU) to either the primary RLC entity (1h-30) or the split secondary RLC entity (1h-31) if the split operation conditions of the split bearer are satisfied (i.e., duplication operation is not enabled for the split bearer and the total amount of data queued in the PDCP and RLC layers to be transmitted to the primary RLC entity and the split secondary RLC entity is greater than or equal to ul-DataSplitThreshold). This split operation may be allowed only in a dual connectivity scenario when RLC entities configured in different cell groups are mapped to the split bearer, in which case the split secondary RLC entity can only be configured with an RLC entity configured in a different cellgroup than the one in which the primary RLC entity is configured. For duplication operation, more than one secondary path (or secondary RLC entity) (1h-32) can be configured per split bearer. Secondary path(1h-32) can be explicitly set via RRC or MAC signaling, or all RLC entities other than the primary path among the RLC entities mapped to the split bearer without explicit setting can be considered as secondary RLC entities(1h-32). The duplication operation of the split bearer can be activated and deactivated on a DRB basis via RRC and MAC layer signaling. If the duplication operation of the split bearer is activated, the PDCP layer can transmit the same packet (PDCP PDU) through the primary RLC entity(1h-30) and one or more secondary RLC entities(1h-32).

FIG. 1i illustrates an example of a packet transmission operation when setting a DRB (Data Radio Bearer) unit split bearer operation according to one embodiment of the present disclosure.

Referring to FIG. 1i, in the present embodiment, the XR traffic flow may be composed of a combination of data (e.g., PDUs or PDU sets corresponding to I-frame (1i-05), B-frame (1i-06), P-frame (1i-07) in the case of video traffic) having different QoS requirements (e.g., delay, reliability-related requirements) and importance, as in FIG. 1c. In addition, data included in the same XR traffic flow may be mapped to one or more QoS flows (1i-01)(1i-41) as in FIG. 1d and delivered to the SDAP layer (1i-10)(1i-50). The SDAP layer may map one or more QoS flows mapped to the same XR traffic flow to the same DRB. At this time, the DRB can be set up as a Split bearer that transmits data through multiple RLC bearers to handle XR traffic with different QOS requirements and importance.

In the present embodiment, as in the above-mentioned FIG. 1h, settings related to the split and duplication operations of the Split bearer (at least one of the primary path, the secondary path, the split secondary path, the ul-DataSplitThreshold, or the duplication operation enable/disable status) can be set per DRB. Therefore, all packets transmitted through the Split bearer can be transmitted according to the same split bearer operation settings. In addition, in the present embodiment, for the sake of ease of explanation, it is assumed that the XR traffic flow is composed of video traffic (e.g., PDUs or PDU sets corresponding to each of I-frame, B-frame, and P-frame) having different QoS requirements and priorities; however, the operations described through the embodiment can be equally applied to general XR traffic flows.

Data (e.g., PDU or PDU set) corresponding to each I-frame (1i-05), B-frame (1i-06), and P-frame (1i-07) included in the same XR traffic flow have different QoS requirements and priorities, and can be delivered to the SDAP (1i-10)(1i-50) layer through one or more QoS flows (or QoS sub-flows)(1i-01)(1i-41). The SDAP layer can map one or more QoS flows mapped to the same XR traffic flow to a DRB set as a split bearer. If the split bearer is set to perform the duplication operation as in the embodiment of FIG. 1h (1i-80), the PDCP layer (1i-20) can perform the duplication operation on all packets through the primary path (1i-31) and secondary path (1i-32) set per DRB unit, without distinguishing between packets (PDCP SDUs) corresponding to each of the I-frame, B-frame, and P-frame. Meanwhile, if the split bearer is set to perform the split operation as in the embodiment of FIG. 1h (1i-90), the PDCP layer (1i-60) can perform the split operation according to the split operation settings set per DRB unit (e.g., Primary path (1i-71), Split secondary path (1i-72), ul-DataSplitThreshold, etc.) without distinguishing between packets (PDCP SDUs) corresponding to each of the I-frame, B-frame, and P-frame. When split bearer operation is set per DRB as in the above embodiment, since duplication (1i-80) and split (1i-90) operations are performed equally for all data transmitted through the corresponding DRB, when XR traffic has different QoS requirements and importance, there may be restrictions in performing duplication and split operations according to the requirements for each packet.

FIG. 1j illustrates an example of a packet transmission operation when setting a split bearer operation of an importance unit of a PDU set according to one embodiment of the present disclosure.

Referring to FIG. 1j, in the present embodiment, the XR traffic flow may be composed of a combination of data having different QoS requirements (e.g., delay, reliability-related requirements) and importance (e.g., PDUs or PDU sets corresponding to each of I-frame (1j-40), P-frame (1j-41), and B-frame (1j-42) in the case of video traffic) as in FIG. 1c. In the present embodiment, for the sake of ease of explanation, it is assumed that the XR traffic flow is composed of video traffic having different QoS requirements and importance (e.g., PDUs or PDU sets corresponding to each of I-frame, B-frame, and P-frame). However, the operations described in the present embodiment may be equally applied to general XR traffic flows. The data included in the XR traffic flow may be mapped to one or more QoS flows (or QoS sub-flows) (1j-01) and delivered to the SDAP layer (1j-10). The SDAP layer can map one or more QoS flows that are mapped to the same XR traffic flow to the same DRB. In this case, the DRB can be configured as a Split bearer that transmits data over multiple RLC bearers to process XR traffic (e.g., PDU sets) with different priorities.

In the present embodiment, as shown in the above-described FIG. 1h, settings related to split and duplication operations of the Split bearer (at least one of primary path, secondary path, split secondary path, ul-DataSplitThreshold, or duplication operation enable/disable status) can be set in units of importance of the PDU set. Accordingly, packets (e.g., PDCP SDUs) transmitted through the same Split bearer can be transmitted according to different Split bearer operation settings depending on their importance (e.g., importance of the PDU set that the packet constitutes), and thus different levels of service can be guaranteed.

This embodiment describes the operation when the split bearer operation is set by importance unit of PDU set. For example, high importance is given to the PDU set corresponding to I-frame (1j-40), and accordingly, duplication operation can be set to ensure a high level of reliability. Therefore, when transmitting the PDU set corresponding to the I-frame in the PDCP layer (1j-20), the same packet can be transmitted in duplicate through the primary RLC entity (1j-31) and the secondary RLC entity (1j-32). A relatively low level of importance is given to the PDU sets corresponding to P-frame (1j-41) and B-frame (1j-42), and accordingly, split operation can be set to increase the data transmission throughput. However, if the PDU sets corresponding to the P-frame (1j-41) and the B-frame (1j-42) have different priorities, different primary RLC entities and split secondary RLC entities may be set according to the priorities of the PDU sets since the RLC/MAC settings (e.g., number of RLC retransmissions, etc.) suitable for transmitting the PDU sets corresponding to each frame type may be different. In this embodiment, an example is shown in which RLC1 (1j-31) is set as the primary path and RLC2 (1j-32) is set as the split secondary path for the importance of the PDU set corresponding to the P-frame (1j-41), and RLC2 (1j-32) is set as the primary path and RLC1 (1j-31) is set as the split secondary path for the importance of the PDU set corresponding to the B-frame (1j-42).

Specifically, the following variables related to split bearer operation can be set separately according to PDU set importance.

- Primary path: LCID (Logical Channel ID) and cell group ID values of the primary RLC entity.

- Split secondary path: LCID value of the split secondary RLC entity. If split operation is not required, split secondary path may not be set. Even if split operation is required, if there are two RLC entities mapped to the corresponding DRB, one RLC entity other than the primary RLC entity can become the split secondary path without explicitly setting the split secondary path.

- Secondary path: LCID value of the secondary path RLC entity. If there are multiple secondary paths, multiple LCID values can be set. If the duplication operation is disabled, the secondary path may not be set. If the duplication operation is enabled but the secondary path is not explicitly set, it may mean that all RLC entities mapped to the DRB, other than the primary RLC entity, are set as secondary paths.

- ul-DataSplitThreshold: The threshold value used for split operation. Split operation can be activated only when the total amount of data waiting in PDCP and RLC layers to be transmitted to the primary RLC entity and the split secondary RLC entity (if this value is set in units of Sets, the total amount of data waiting in units of Sets can be calculated individually.) is greater than or equal to ul-DataSplitThreshold. If this value is set to infinity, packets can be transmitted only through the primary path.

- pdcp-Duplication (or duplicationState): A variable that indicates the activation status of the duplication operation. If the value is set to 'True', it means that duplication is activated. If two or more secondary RLC entities are set, you can individually indicate whether the duplication operation is activated for each secondary RLC entity.

FIG. 1k illustrates a signaling procedure between a terminal and a base station for setting and operating a terminal operation based on PDU set importance in a next-generation mobile communication system according to an embodiment of the present disclosure.

Referring to Figure 1k, a signaling procedure between a terminal (1k-01) and a base station (1k-03) for setting and operating terminal operation based on PDU set importance is shown. The procedure for each step is as follows.

- UECapabilityEnquiry(gNB->UE)(1k-10): gNB(1k-03) can transmit UECapabilityEnquiry message requesting capability report to RRC connected state terminal(1k-01). gNB(1k-03) can include terminal capability request by RAT(radio access type) type in the UECapabilityEnquiry message. The request by RAT type can include requested frequency band information. In addition, when gNB(1k-03) requests generation of UECapabilityInformation message to terminal(1k-01), filtering information that can indicate conditions and restrictions can be included. At this time, through the filtering information, the gNB (1k-03) can instruct the terminal (1k-01) whether to report capabilities related to terminal operations based on PDU set importance (e.g., BSR triggering operation considering PDU set importance, LCP operation, split bearer setup, etc.).

- UECapabilityInformation(UE->gNB)(1k-11): The terminal (1k-01) can generate a UECapabilityInformation message corresponding to the UECapabilityEnquiry(1k-10) message and report a response to the request to the gNB (1k-03). At this time, the UECapabilityInformation message can include a parameter indicating whether the terminal (1k-01) supports a terminal operation based on PDU set importance (Importance) (e.g., BSR triggering operation considering PDU set importance, LCP operation, split bearer configuration, etc.). The gNB (1k-03) can determine whether the terminal (1k-01) supports the terminal operation based on PDU set importance (Importance) based on the received UECapabilityInformation message.

- UEAssistanceInformation(UE->gNB)(1k-12): The UE (1k-01) can transmit to the gNB (1k-03) the assistance information required to set the UE operation by PDU set importance by including it in the UEAssistanceInformation message. For example, the importance of each PDU set transmitted through one or more QoS flows and the corresponding QoS requirements (e.g., delay and reliability requirements) and traffic characteristics (e.g., period and data size) information can be included in the UEAssistanceInformation message.

- QoS profile(CN->gNB)(1k-13): Core network(CN)(1k-05) can transmit QoS profile information required for gNB(1k-03) to set terminal operation (e.g., BSR triggering operation considering PDU set importance, LCP operation, split bearer setting) by PDU set importance(Importance). At this time, the importance of each PDU set transmitted through one or more QoS flows and corresponding QoS requirements (e.g., delay and reliability requirements) and traffic characteristics (e.g., period and data size) information can be included in the QoS profile. The CN of step 1k-13 can be, but is not limited to, SMF(session management function), AMF, or PCF(policy control function).

- RRCReconfiguration(gNB->UE)(1k-14): gNB(1k-03) can send RRCReconfiguration message to UE(1k-01) to set UE operation (e.g. BSR triggering operation considering PDU set importance, LCP operation, split bearer setting, etc.) according to PDU set importance. At this time, the following setting information can be included in the RRCReconfiguration message.

For example, when the terminal performs a BSR triggering operation in the MAC layer as described in the above-described FIG. 1f, an indicator (e.g., BSRbasedOnImportance) for setting consideration of the importance of UL data (in other words, the importance of the PDU set composed of the corresponding UL data) may be included in the configuration information for the MAC operation (e.g., MAC-CellGroupConfig).

For example, when a terminal performs an LCP operation in the MAC layer as described in the above drawings 1ga and 1gb, an indicator (e.g., SchedulingBasedonImportance) for setting consideration of the importance of UL data (in other words, the importance of the PDU set composed of the corresponding UL data) may be included in the configuration information for the MAC operation (e.g., MAC-CellGroupConfig).

As another example, an indicator (e.g., HandlingImportance) may be set on a per-DRB (or per-PDCP entity) basis to indicate whether packets transmitted through a PDCP connected to a specific DRB can be handled differently depending on the importance of each packet (in other words, the importance of the PDU set that the packet constitutes). When the indicator is set, the following parameters related to the Split bearer operation configuration as described in the above-described Fig. 1j may be included according to the importance of the PDU set.

* Primary path, Split secondary path, Secondary path, ul-DataSplitThreshold, pdcp-Duplication (or duplicationState)

As another example, when different delay requirements are required for each importance of a PDU set, a discardTimer value can be set for each importance of the PDU set for discarding packets at the PDCP layer. The discardTimer value can be used for discarding PDCP SDU packets corresponding to the importance of the PDU set. For example, when a PDCP SDU packet arrives at the PDCP layer, a discard timer is started, and when the timer value reaches the discardTimer value set for the importance of the PDU set corresponding to the packet, the packet can be discarded when the timer expires. If the L2 transmission for the packet is successful before the discardTimer expires, the terminal can terminate the discardTimer and discard the packet.

- RRCReconfigurationComplete(UE->gNB)(1k-15): The UE (1k-01) can apply the settings included in the RRCReconfiguration message received from the gNB (1k-03) in step 1k-14 and send the RRCReconfigurationComplete message to report to the gNB that the settings have been completed.

- MAC CE for Duplication Activation/deactivation per Set (gNB->UE)(1k-16): gNB (1k-03) can transmit MAC CE to UE (1k-01) to activate or deactivate the duplication operation of Split bearer set in importance unit of PDU set. For this purpose, Duplication Activation/Deactivation MAC CE can be recycled (for example, UE operation can be changed upon receiving the corresponding MAC CE) or a new MAC CE can be defined as in Fig. 1l below.

- MAC CE for Duplication RLC Activation per set (gNB->UE)(1k-17): If there are two or more RLC entities available as secondary path (or secondary RLC path) for duplication operation (or three or more RLC entities connected to the corresponding DRB), gNB (1k-03) can transmit MAC CE to UE (1k-01) to activate or deactivate duplication operation of each RLC entity in importance unit of PDU set. For this purpose, Duplication RLC Activation/Deactivation MAC CE can be recycled (for example, UE operation can be changed upon receiving the corresponding MAC CE) or a new MAC CE can be defined as in Fig. 1l below.

Additionally, if the HandlingImportance indication is set (true) for a specific DRB (or PDCP entity corresponding to the DRB), when the terminal receives a retransmission resource addressed to a configured scheduling radio network temporary identifier (CS-RNTI) value (i.e., a retransmission grant addressed to CS-RNTI), all RLC entities connected to the PDCP entity can be activated for PDCP duplication operation.

FIG. 1l illustrates a MAC CE structure that can be used to enable/disable PDCP duplication on a per-PDU set importance basis according to one embodiment of the present disclosure.

Referring to FIG. 1l, FIGS. 1l-01, 1l-02 and 1l-03 show examples of newly defined MAC CEs for enabling or disabling the Duplication operation of a Split bearer set in PDU set importance units as in step 1k-16.

In Fig. 1l-01, the DRB ID indicates the DRB to which the corresponding MAC CE is applied, and each IPT_i value can indicate the duplication operation activation status for the corresponding PDU set importance. Therefore, when the MAC CE is defined as in the above 1l-01, duplication operation activation or deactivation for multiple PDU set importances can be indicated through a single MAC CE transmission. At this time, i in IPT_i can be the ascending or descending order of the PDU set importance set in the DRB indicated through the DRB ID. When the IPT_i value is set to 1, this can indicate duplication function activation for the corresponding PDU set importance, and when it is set to 0, this can indicate duplication function deactivation for the corresponding PDU set importance. In this example, it is assumed that there are at most 3 PDU set importances mapped to one DRB (3 bits are used for IPT_i value), but the structure of MAC CE can be extended so that more than 4 bits can be used for IPT_i value if more than 4 PDU set importances can be transmitted through the same DRB.

In Fig. 1l-02, the DRB ID indicates the DRB to which the corresponding MAC CE is applied, and the IPT ID value can indicate a PDU set importance value for which duplication operation is to be enabled or disabled. Therefore, when the MAC CE is defined as in 1l-02, one MAC CE transmission can indicate activation or deactivation of duplication operation for one PDU set importance. If it is desired to simultaneously activate or deactivate duplication operation for multiple PDU set importances set to a specific DRB using the same structure, the 1l-02 structure can be extended to include multiple IPT IDs.

In Fig. 1l-03, each IPT_i value can indicate duplication operation activation status for the corresponding PDU set importance. Therefore, if MAC CE is defined as in the above 1l-03, duplication operation activation or deactivation for multiple PDU set importances can be indicated through a single MAC CE transmission. At this time, i in IPT_i can be the ascending or descending order of PDU set importance set to the corresponding terminal. (In this case, it is assumed that the PDU set importance for each PDU set importance is uniquely set within the corresponding terminal.) If the IPT_i value is set to 1, this can indicate duplication function activation for the corresponding set, and if it is set to 0, this can indicate duplication function deactivation for the corresponding set. In this example, it is assumed that the maximum number of PDU set priorities set for the terminal is 8 (8 bits are used for the IPT_i value), but if more than 9 PDU set priorities can be set for the same terminal, the structure of MAC CE can be extended so that more than 9 bits can be used for the IPT_i value.

In Fig. 1l-04, the DRB ID indicates the DRB to which the corresponding MAC CE is applied, and the IPT Threshold value can indicate the threshold value of the PDU set importance for activating or deactivating the duplication operation. Therefore, when the MAC CE is defined as in 1l-04, the IPT Threshold value for activating or deactivating the duplication operation based on the PDU set importance value can be indicated through a single MAC CE transmission in a specific DRB. In this case, the terminal can activate duplication only for packets having a higher importance than the IPT Threshold among the packets (i.e., PDCP SDUs) transmitted through the corresponding DRB.

Figures 1l-10 and 1l-11 show the MAC CE structures that can be used to enable or disable duplication operation for each RLC entity on a per PDU set importance basis when there are two or more RLC entities available as secondary path (or secondary RLC path) for duplication operation for a specific PDU set importance (or when there are three or more RLC entities connected to the corresponding DRB).

In Fig. 1l-10, the IPT ID can indicate the PDU set importance to which the corresponding MAC CE is to be applied. (In this case, it is assumed that each PDU set importance is uniquely set within the corresponding terminal.) In addition, each RLC_i value can indicate the duplication operation activation status for the corresponding RLC entity. At this time, in RLC_i, i can be the ascending or descending LCID values of the RLC entities set as secondary path for the PDU set importance indicated through the IPT ID (or for the DRB to which the PDU set importance indicated through the IPT ID is mapped). If the RLC_i value is set to 1, this can indicate duplication function activation for the corresponding RLC entity, and if it is set to 0, this can indicate duplication function deactivation for the corresponding RLC entity. In this example, it is assumed that there are at most 3 secondary paths set for one PDU set importance (3 bits are used for RLC_i value), but the structure of MAC CE can be extended so that more than 4 bits can be used for RLC_i value when 4 or more RLC entities are set as secondary paths for the corresponding PDU set importance.

In Fig. 1l-11, the DRB ID and IPT id can indicate the DRB and PDU set importance to which the corresponding MAC CE is applied, respectively. (In this case, it is assumed that the IPT ID for the PDU set importance is uniquely set per DRB.) In addition, each RLC_i value can indicate the duplication operation activation status for the corresponding RLC entity. At this time, in RLC_i, i can be the ascending or descending LCID values of the RLC entities set as the secondary path for the PDU set importance indicated by the IPT ID (or for the DRB indicated by the DRB ID). If the RLC_i value is set to 1, this can indicate activation of the duplication function for the corresponding RLC entity, and if it is set to 0, this can indicate deactivation of the duplication function for the corresponding RLC entity. In this example, it is assumed that there are up to 8 secondary paths set for one PDU set importance (8 bits are used for the RLC_i value), but the structure of MAC CE can be extended so that more than 9 bits can be used for the RLC_i value when more than 9 RLC entities are set as secondary paths for the set.

FIG. 1m is a block diagram illustrating the internal structure of a terminal according to one embodiment of the present disclosure.

Referring to FIG. 1m, the terminal includes an RF (Radio Frequency) processing unit (1m-10), a baseband processing unit (1m-20), a storage unit (1m-30), and a control unit (1m-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 (1m-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 (1m-10) up-converts a baseband signal provided from the baseband processing unit (1m-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 (1m-10) may include a transmitting filter, a receiving filter, an amplifier, a mixer, an oscillator, a digital to analog convertor (DAC), an analog to digital convertor (ADC), etc. In FIG. 2, only one antenna is illustrated, but the terminal may have multiple antennas. In addition, the RF processing unit (1m-10) may include multiple RF chains. Furthermore, the RF processing unit (1m-10) may perform beamforming. For beamforming, the RF processing unit (1m-10) may adjust the phase and size of each of the signals transmitted and received through the multiple antennas or antenna elements. In addition, the RF processing unit (1m-10) may perform MIMO (multi input multi output) and may receive multiple layers when performing a MIMO operation. The RF processing unit (1m-10) can perform receiving beam sweeping by appropriately setting multiple antennas or antenna elements under the control of the control unit (1m-40), or adjust the direction and beam width of the receiving beam so that the receiving beam is coordinated with the transmitting beam.

The baseband processing unit (1m-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 (1m-20) can generate complex symbols by encoding and modulating a transmission bit stream. In addition, when receiving data, the baseband processing unit (1m-20) can restore a reception bit stream by demodulating and decoding a baseband signal provided from the RF processing unit (1m-10). For example, in the case of following the OFDM (orthogonal frequency division multiplexing) method, when transmitting data, the baseband processing unit (1m-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 (1m-20) divides the baseband signal provided from the RF processing unit (1m-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 (1m-20) and the RF processing unit (1m-10) can transmit and receive signals as described above. The baseband processing unit (1m-20) and the RF processing unit (1m-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 (1m-20) and the RF processing unit (1m-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 (1m-20) and the RF processing unit (1m-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 a baseband processing unit (1m-20) and an RF processing unit (1m-10), and the signals may include control information and data.

The storage unit (1m-30) can store data such as basic programs, application programs, and setting information for the operation of the terminal. In particular, the storage unit (1m-30) can store information related to a second access node that performs wireless communication using a second wireless access technology. In addition, the storage unit (1m-30) can provide the stored data according to a request of the control unit (1m-40). In addition, the storage unit (1m-30) can be composed of a plurality of memories. According to one embodiment, the storage unit (1m-30) can store a program for performing the split bearer operation method of the present disclosure.

The control unit (1m-40) can control the overall operations of the terminal. For example, the control unit (1m-40) can transmit and receive signals through the baseband processing unit (1m-20) and the RF processing unit (1m-10). In addition, the control unit (1m-40) can record and read data in the storage unit (1m-40). To this end, the control unit (1m-40) can include at least one processor. For example, the control unit (1m-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 (1m-40) can include a multi-connection processing unit (1m-42) that performs processing for operating in a multi-connection mode.

FIG. 1n is a block diagram showing the configuration of a base station according to one embodiment of the present disclosure.

Referring to FIG. 1n, the base station may include an RF processing unit (1n-10), a baseband processing unit (1n-20), a backhaul communication unit (1n-30), a storage unit (1n-40), and a control unit (1n-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 (1n-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 (1n-10) can up-convert a baseband signal provided from the baseband processing unit (1n-20) into an RF band signal and transmit the same through an antenna, and down-convert an RF band signal received through the antenna into a baseband signal. For example, the RF processing unit (1n-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 be equipped with multiple antennas. In addition, the RF processing unit (1n-10) can include multiple RF chains. Furthermore, the RF processing unit (1n-10) can perform beamforming. For beamforming, the RF processing unit (1n-10) can adjust the phase and size of each signal transmitted and received through multiple antennas or antenna elements. The RF processing unit (1n-10) can perform a downward MIMO operation by transmitting one or more layers. The RF processing unit (1n-10) can perform reception beam sweeping by appropriately setting multiple antennas or antenna elements according to 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 (1n-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 (1n-20) can generate complex symbols by encoding and modulating a transmission bit stream. In addition, when receiving data, the baseband processing unit (1n-20) can restore a reception bit stream by demodulating and decoding a baseband signal provided from the RF processing unit (1n-10). For example, in the case of following the OFDM method, when transmitting data, the baseband processing unit (1n-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 (1n-20) can divide the baseband signal provided from the RF processing unit (1n-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 (1n-20) and the RF processing unit (1n-10) can transmit and receive signals as described above. Accordingly, the baseband processing unit (1n-20) and the RF processing unit (1n-10) may 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 (1n-20) and the RF processing unit (1n-10), and the signals may include control information and data.

The backhaul communication unit (1n-30) can provide an interface for performing communication with other nodes within the network. That is, the backhaul communication unit (1n-30) can convert a bit string transmitted from a main base station to another node, such as an auxiliary base station or a core network, into a physical signal, and can convert a physical signal received from another node into a bit string.

The storage unit (1n-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 (1n-40) can store information on bearers allocated to connected terminals, measurement results reported from connected terminals, and the like. In addition, the storage unit (1n-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 (1n-40) can provide stored data according to a request from the control unit (1n-50). The storage unit (1n-40) can also store a program for performing the split bearer operation method of the present disclosure.

The control unit (1n-50) can control the overall operations of the base station. For example, the control unit (1n-50) can transmit and receive signals through the baseband processing unit (1n-20) and the RF processing unit (1n-10) or through the backhaul communication unit (1n-30). In addition, the control unit (1n-50) can record and read data in the storage unit (1n-40). For this purpose, the control unit (1n-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, according to one embodiment of the present disclosure, the control unit (1n-50) can include a multi-connection processing unit (1n-52) that performs processing for operating in a multi-connection mode. 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 disclosure are expressed in the singular or plural form depending on the specific embodiment presented. However, the singular or plural expressions are selected to suit the presented situation for 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.

In addition, the methods described in FIGS. 1A to 1L of the present disclosure may include methods in which at least one of the drawings is combined according to various implementations. For example, FIGS. 1A to 1N may be combined (performed) to form a single flow. In addition, a part or all of an embodiment of the present disclosure may be performed in combination with a part or all of one or more other embodiments. The present disclosure may include methods in which at least one of the drawings is combined according to various implementations.

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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