Method and apparatus for controlling beam failure detection in wireless communication system

Abstract

The invention relates to a method and device for controlling beam fault detection. The present disclosure provides a method of receiving, from a base station, a Radio Resource Control (RRC) message configuring one or more Beam Fault Detection (BFD) sets, where each of the one or more BFD sets includes at least one BFD Reference Signal (BFD-RS); identifying that the BFD-RSs are activated for the corresponding BFD set under the condition that the number of the BFD-RSs of the corresponding BFD set is smaller than or equal to a threshold value; and identifying that the BFD-RSs are deactivated for the respective BFD set if the number of BFD-RSs for the respective BFD set is greater than the threshold value.

Description

Technical Field

[0001] The present disclosure relates to a wireless communication system, and more particularly, to a method, device and / or system for controlling beam failure detection (BFD) in a wireless communication system. Background Art

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

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

[0004] Currently, discussions on improvements and performance enhancements of initial 5G mobile communication technologies are being conducted in consideration of services to be supported by the 5G mobile communication technologies, and there is already physical layer standardization on technologies such as: V2X (Vehicle to Everything) for assisting driving determination by autonomous vehicles based on information about the location and status of the vehicle sent by the vehicle and enhancing user convenience, NR-U (Unlicensed New Radio) for system operation that aims to comply with regulatory requirements in unlicensed bands, NR UE power saving, Non-Terrestrial Network (NTN) for UE-satellite direct communication for providing coverage and positioning in areas where communication with terrestrial networks is unavailable.

[0005] Furthermore, standardization in air interface architecture / protocols has been conducted with respect to technologies such as Industrial Internet of Things (IIoT) for supporting new services through interaction and convergence with other industries, IAB (Integrated Access and Backhaul) for providing nodes for network service area extension by supporting wireless backhaul links and access links in an integrated manner, mobility enhancement including conditional handover and DAPS (Dual Active Protocol Stack) handover, and two-step random access (2-step RACH for NR) for simplifying the random access procedure. Standardization of system architecture / services for a 5G reference architecture (e.g., service-based architecture or service-based interface) for combining network function virtualization (NFV) and software defined network (SDN) technologies, and mobile edge computing (MEC) for receiving services based on UE location has also been conducted.

[0006] With the commercialization of 5G mobile communication systems, the number of connected devices that have been exponentially increasing will be connected to the communication network, so it can be expected that enhanced functions and performance of 5G mobile communication systems and integrated operations of connected devices will be necessary. To this end, new research is planned related to the following items: Extended Reality (XR) for efficiently supporting AR (Augmented Reality), VR (Virtual Reality), MR (Mixed Reality), etc., 5G performance improvement and complexity reduction by utilizing artificial intelligence (AI) and machine learning (ML), AI service support, Metaverse service support, and drone communication.

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

[0008] Meanwhile, as discussed above, with the development of wireless communication systems, solutions for seamlessly providing various services are needed. In particular, a solution for beam failure detection (BFD) that efficiently controls communication is needed. Summary of the invention

[0009] Solution to the problem The present disclosure provides an apparatus and method for efficiently providing various services in a wireless communication system or a mobile communication system.

[0010] In order to support beam failure detection in a next generation mobile communication system using beams (specifically, in multiple transmit receive points (TRPs)), a terminal needs to be configured with beam resource information sent from a corresponding TRP and listen to it. More specifically, the present disclosure proposes an operation associated with a medium access control (MAC) control element (CE), which indicates resource activation for beam failure detection at multiple TRPs.

[0011] According to an embodiment of the present disclosure, a method performed by a terminal is provided. The method includes: receiving a radio resource control (RRC) message configuring one or more beam failure detection (BFD) sets from a base station, wherein each of the one or more BFD sets includes at least one BFD reference signal (BFD-RS); in a case where the number of BFD-RSs of the corresponding BFD set is less than or equal to a threshold, identifying that the BFD-RS of the corresponding BFD set is activated; and in a case where the number of BFD-RSs of the corresponding BFD set is greater than the threshold, identifying that the BFD-RS of the corresponding BFD set is deactivated.

[0012] According to an embodiment of the present disclosure, a method performed by a base station is provided. The method includes: sending a radio resource control (RRC) message to a terminal to configure one or more beam failure detection (BFD) sets, wherein each of the one or more BFD sets includes at least one BFD reference signal (BFD-RS); activating the BFD-RS of the corresponding BFD set when the number of BFD-RSs of the corresponding BFD set is less than or equal to a threshold; and deactivating the BFD-RS of the corresponding BFD set when the number of BFD-RSs of the corresponding BFD set is greater than the threshold.

[0013] According to an embodiment of the present disclosure, a terminal is provided. The terminal includes: a transceiver; and a controller, the controller being coupled to the transceiver and configured to: receive a radio resource control (RRC) message configuring one or more beam failure detection (BFD) sets from a base station, wherein each of the one or more BFD sets includes at least one BFD reference signal (BFD-RS), and when the number of BFD-RSs of the corresponding BFD set is less than or equal to a threshold, identify that the BFD-RS of the corresponding BFD set is activated, and when the number of BFD-RSs of the corresponding BFD set is greater than the threshold, identify that the BFD-RS of the corresponding BFD set is deactivated.

[0014] According to an embodiment of the present disclosure, a base station is provided. The base station includes: a transceiver; and a controller, the controller being coupled to the transceiver and configured to: send a radio resource control (RRC) message to a terminal to configure one or more beam failure detection (BFD) sets, wherein each of the one or more BFD sets includes at least one BFD reference signal (BFD-RS), activate the BFD-RS of the corresponding BFD set when the number of BFD-RSs of the corresponding BFD set is less than or equal to a threshold, and deactivate the BFD-RS of the corresponding BFD set when the number of BFD-RSs of the corresponding BFD set is greater than the threshold.

[0015] According to the embodiments of the present disclosure, beam failure can be efficiently controlled in a wireless communication system or a mobile communication system so as to effectively and seamlessly provide various services.

[0016] Before proceeding to the following detailed description, it may be helpful to set forth definitions of certain words and phrases used throughout this patent document; the terms "include" and "comprising" and their derivatives mean including but not limiting; the term "or" is inclusive, meaning and / or; the phrases "associated with" and "associated with" and their derivatives may mean including, included, interconnected with, contained, contained within, connected to or connected with, coupled to or coupled with, communicable with, cooperating with, interlaced, juxtaposed, proximate to, bound to and bound with, having, having the property of, and the like; and the term "controller" means any device, system, or part thereof that controls at least one operation, such device may be implemented in hardware, firmware, or software, or some combination of at least two thereof. It should be noted that any functionality associated with a particular controller may be centralized or distributed, whether locally or remotely.

[0017] Moreover, various functions as described below can be implemented or supported by one or more computer programs, each of which is formed by a computer-readable program code and embodied in a computer-readable medium. The terms "application" and "program" refer to one or more computer programs, software components, instruction sets, procedures, functions, objects, classes, instances, related data, or parts thereof suitable for implementation with suitable computer-readable program codes. The phrase "computer-readable program code" includes any type of computer code, including source code, object code, and executable code. The phrase "computer-readable medium" includes any type of medium that can be accessed by a computer, such as a read-only memory (ROM), a random access memory (RAM), a hard drive, a compact disk (CD), a digital video disk (DVD), or any other type of memory. "Non-transitory" computer-readable media exclude wired, wireless, optical, or other communication links that convey instantaneous electrical signals or other signals. Non-transitory computer-readable media include media in which data can be permanently stored and media in which data can be stored and later rewritten, such as rewritable optical disks or erasable memory devices.

[0018] Definitions for certain words and phrases are provided throughout this patent document, those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] For a more complete understanding of the present disclosure and advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings, wherein like reference numerals represent like parts.

[0020] Figure 1 A diagram showing a mobile communication system structure to which the present disclosure is applied.

[0021] Figure 2 A diagram showing a wireless protocol structure of a mobile communication system to which the present disclosure is applied.

[0022] Figure 3 A diagram showing another mobile communication system structure to which the present disclosure is applied.

[0023] Figure 4 A diagram showing scenarios of cell-level and transmit reception point (TRP)-level beam failure detection / recovery procedures in a next-generation mobile communication system to which the present disclosure is applied.

[0024] Figure 5 A diagram showing a cell-level beam failure detection and recovery process using multiple TRPs adopted in a new radio (NR) system referenced in this disclosure is shown.

[0025] Figure 6 A diagram showing a TRP-level beam failure detection and recovery process using multiple TRPs adopted in an NR system as applied to the present disclosure.

[0026] Figure 7 A diagram showing a medium access control (MAC) control element (CE) structure for activating / updating beam failure detection (BFD) reference signal (RF) per TRP referenced in this disclosure.

[0027] Figure 8 A diagram showing a method in which a terminal receives a BFD RS set per TRP from a base station and performs BFD RS monitoring when a BFD RS indication MAC CE is received according to an embodiment of the present disclosure.

[0028] Fig. 9 A diagram showing a method of receiving a BFD RS set per TRP from a base station and performing BFD RS monitoring before a terminal receives a BFD RS indication MAC CE according to an embodiment of the present disclosure.

[0029] Fig.10 A diagram showing the operation of a base station to which an embodiment of the present disclosure is applied.

[0030] Fig.11 A block diagram showing a terminal structure to which the present disclosure is applied.

[0031] Fig.12 A block diagram showing a base station structure to which the present disclosure is applied is shown. DETAILED DESCRIPTION

[0032] The following discussion Figures 1 to 12 The various embodiments used to describe the principles of the present disclosure in this patent document are only for illustration and should not be interpreted in any way as limiting the scope of the present disclosure. Those skilled in the art will understand that the principles of the present disclosure can be implemented in any appropriately arranged system or device.

[0033] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In this case, please note that similar reference numerals in the accompanying drawings represent similar elements. In addition, detailed descriptions related to well-known functions or configurations that may make the subject matter of the present disclosure unnecessarily obscure should be omitted.

[0034] When describing the embodiments, technical contents that are well known in the technical field to which the present disclosure belongs and are not directly related to the present disclosure will be omitted in the specification. This is to provide the subject matter of the present disclosure more clearly by omitting unnecessary descriptions without obscuring the subject matter of the present disclosure.

[0035] For the same reason, some components in the drawings are exaggerated, omitted or schematically shown. Moreover, the size of each component does not fully reflect the actual size. The same reference numerals are given to the same or corresponding elements in each figure.

[0036] Reference will be made to the following and attached Figure 1 The embodiments described in detail below are used to clarify the advantages and features of the present disclosure and methods for achieving the same. However, the present disclosure is not limited to the embodiments disclosed below, but can be implemented in various different forms. The embodiments are provided only to complete the scope of the present disclosure and to enable those skilled in the art to which the present disclosure belongs to fully understand the category of the present disclosure, and the present disclosure is limited only to the scope of the claims. The same reference numerals refer to the same elements throughout the specification.

[0037] At this point, it will be understood that each box of the process flow diagram and the combination of the flow diagram can be performed by computer program instructions. Because these computer program instructions can be installed on a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, the instructions executed by the processor of the computer or other programmable data processing device can generate a device for performing the functions described in the process box. Because these computer program instructions can also be stored in a computer-available or computer-readable memory that can guide the computer or other programmable data processing device to operate in a specific manner, the instructions stored in the computer-available or computer-readable memory produce an article, which includes an instruction device that implements the functions described in the process box. Because the computer program instructions can also be loaded on a computer or other programmable data processing device, a series of operating steps can be performed on the computer or other programmable data processing device to generate a computer-executed process, so the instructions of the execution computer or other programmable data processing device can provide for performing the functions described in the process box.

[0038] In addition, each box may represent a module, segment or part of a code that includes one or more executable instructions for implementing a specified logical function. Moreover, it should be noted that in some alternative implementations, the functions mentioned in the box may appear out of order. For example, depending on the corresponding functions, two boxes shown in succession may actually be executed substantially concurrently, or sometimes the boxes may be executed in reverse order.

[0039] At this time, the term "~ unit" used in the current embodiment represents a software or hardware component such as a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC), and the "~ unit" performs a specific function. However, the "~ unit" is not limited to software or hardware. The "~ unit" can be configured to exist in an addressable storage medium and is configured to be reproduced on one or more processors. Therefore, for example, the "~ unit" may include, for example, components (e.g., software components, object-oriented software components, class components, and task components), processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcodes, circuits, data, databases, data structures, tables, arrays, and variables. The functions provided in the components and "units" can be combined into fewer components and "units", or can be divided into additional components and "units". In addition, these components and "~ units" can be implemented as one or more central processing units (CPUs) in a reproduction device or a secure multimedia card. Moreover, in one embodiment, the "~ unit" may include one or more processors.

[0040] For ease of description only, terms for identifying access nodes, terms for indicating network entities, terms for indicating messages, terms for indicating interfaces between network entities, and terms for indicating various identification information used in the following description are shown. Therefore, the present disclosure is not limited to the terms to be described, and other terms with the same technical meaning may be used.

[0041] Hereinafter, for convenience of description, terms and names defined in the 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) standard may be used. However, the present disclosure is not limited to these terms and names and may be applied to systems conforming to other standards in the same manner.

[0042] Hereinafter, a base station as an entity for performing resource allocation of a terminal may be at least one of a next generation Node B (gNB), an evolved Node B (eNB), a Node B, a radio access unit, a base station controller, or a node on a network. In the present disclosure, eNB and gNB may be used interchangeably for ease of explanation. That is, a base station described as an eNB may also indicate a gNB. The terminal may include a user equipment (UE), a mobile station (MS), a cellular phone, a smart phone, a computer, or a multimedia system that performs a communication function. It is noteworthy that the present disclosure is not limited to those examples.

[0043] Specifically, the present disclosure may be applied to 3GPP New Radio (NR) (5G mobile communication standard). The present disclosure may be applied to smart services based on 5G communication and Internet of Things (IoT) related technologies (such as smart home, smart building, smart city, smart car, connected car, health care, digital education, retail, safety and security services, etc.). Moreover, the term "terminal" may indicate other wireless communication devices as well as narrowband (NB)-IoT devices and sensors.

[0044] Wireless communication systems are evolving from early voice-oriented services to broadband wireless communication systems for providing high-speed, high-quality packet data services according to communication standards such as 3GPP's High Speed ​​Packet Access (HSPA), LTE, Evolved Universal Terrestrial Radio Access (E-UTRA), Advanced LTE (LTE-A), LTE-Pro, 3GPP2's High Rate Packet Data (HRPD), Ultra Mobile Broadband (UMB), and Institute of Electrical and Electronics Engineers (IEEE) 802.16e.

[0045] As a representative example of a broadband wireless communication system, the LTE system adopts an orthogonal frequency division multiplexing (OFDM) scheme in the downlink (DL) and a single carrier frequency division multiple access (SC-FDMA) scheme in the uplink (UL). UL refers to a wireless link through which a terminal (or UE) sends data or a control signal to a base station (or eNB, gNB), and DL refers to a wireless link through which a base station sends data or a control signal to a terminal. This multiple access scheme distinguishes the data or control information of each user by allocating and operating the time-frequency resources used to carry the data or control information of each user to be non-overlapping, that is, establishing orthogonality.

[0046] As the future communication system after LTE, that is, the 5G communication system, it should be able to freely reflect the various needs of users and service providers, and should support services that meet various needs simultaneously. The services considered for the 5G communication system include enhanced mobile broadband (eMBB), massive machine type communication (mMTC), ultra-reliable low latency communication (URLLC), etc.

[0047] According to an embodiment, eMBB aims to provide a faster data rate than the data rate supported by the existing LTE, LTE-A or LTE-Pro. For example, in terms of a base station, the eMBB in the 5G communication system should be able to provide a peak data rate of 20 gigabits per second (Gbp) in the DL and a peak data rate of 10 Gbps in the UL. In addition, the 5G communication system should provide a peak data rate and simultaneously provide an increased user-perceived data rate of the terminal. In order to meet these requirements, it is necessary to improve various transmission and reception technologies, including more advanced multiple-input multiple-output (MIMO) transmission technologies. In addition, when a maximum 20 megahertz (MHz) transmission bandwidth is used to transmit signals in the 2 GHz band used by LTE, the 5G communication system uses a frequency bandwidth wider than 20 MHz in a frequency band of 3~6 GHz or 6 GHz or higher, thereby meeting the required data rate in the 5G communication system.

[0048] Meanwhile, 5G communication systems are considering mMTC to support application services such as IoT. mMTC requires large-scale terminal access support in a cell, enhanced terminal coverage, improved battery time, and reduced terminal costs to efficiently provide IoT. IoT is attached to various sensors and various devices to provide communication functions, so it should be able to support a large number of terminals in a cell (e.g., 1,000,000 terminals / km 2 ). In addition, mMTC-enabled terminals are likely to be located in shaded areas not covered by cells, such as basements of buildings, due to their service characteristics, and therefore may require wider coverage than other services provided by 5G communication systems. Because it is difficult to frequently replace the battery of a terminal, a terminal that supports mMTC should be configured with a low-cost terminal and may require a fairly long battery life, such as 10 to 15 years.

[0049] Finally, URLLC is a cellular-based wireless communication service for mission-critical purposes and can be used for robotic or mechanical remote control, industrial automation, drones, remote healthcare, emergency alerts, etc. Therefore, the communication provided by URLLC should provide very low latency (ultra-low latency) and very high reliability (ultra-high reliability). For example, a service supporting URLLC should meet an air interface latency of less than 0.5 milliseconds and at the same time have a reliability of less than 10 -5 Therefore, for services supporting URLLC, the 5G system should provide a transmission time interval (TTI) that is smaller than other services, and at the same time require a design problem for allocating wide resources in the frequency band to obtain communication link reliability.

[0050] The three services of the 5G communication system, namely, eMBB, URLLC and mMTC, can be multiplexed and transmitted in one system. At this time, in order to meet the different needs of the corresponding services, different transmission and reception schemes and transmission and reception parameters can be used between services. It is worth noting that the aforementioned mMTC, URLLC and URLLC 5G are only examples of different service types, and the service types according to the present disclosure are not limited to those examples.

[0051] In addition, LTE, LTE-A, LTE Pro, 5G (or NR) or 6G systems can be used as examples to illustrate the embodiments of the present disclosure, but the embodiments of the present disclosure can be applied to other communication systems with similar technical backgrounds or channel forms. In addition, based on the determination of those skilled in the art, the present disclosure can also be applied to other communication systems with some modifications without significantly departing from the scope of the present disclosure.

[0052] Figure 1 A diagram showing a mobile communication system structure to which the present disclosure is applied.

[0053] Reference Figure 1 , the radio access network of the next generation mobile communication system includes NR Node B (NR NB) 1-10 and NR Core Network (NR CN) or Next Generation Core Network (NG CN) 1-05. NR UE or terminal 1-15 accesses the external network via NR NB 1-10 and NR CN 1-05.

[0054] exist Figure 1In the present invention, NR NB 1-10 (or gNB) corresponds to the eNB of the existing LTE system. NR NB 1-10 can be connected to NR UE 1-15 through a wireless channel to provide more advanced services compared with the existing Node B. Because each user service is served by a shared channel in the next generation mobile communication system, a device for performing scheduling by collecting status information of the terminal (or UE) such as buffer status, available transmission power status, and channel status is required, which is managed by NR NB 1-10. One NR NB generally controls multiple cells. In order to achieve ultra-high-speed data transmission compared with the LTE system, a maximum bandwidth greater than the existing maximum bandwidth can be used, and a beamforming technology can be adopted in addition to OFDM as a radio access technology. Moreover, adaptive modulation & coding (AMC) that determines a modulation scheme and a channel coding rate based on the channel status of the UE is applied. NR CN 1-05 performs functions such as mobility support, bearer setting, quality of service (QoS) setting, etc. NR CN1-05 is a device that not only performs a mobility management function for UE but also performs various control functions and is connected to multiple base stations. The next generation mobile communication system can also cooperate with the existing LTE system, and the NR CN 1-105 is connected to the mobility management entity (MME) 1-25 through a network interface. The MME 1-25 is connected to the eNB 1-30 which is an existing base station.

[0055] Figure 2 A diagram showing a wireless protocol structure of a mobile communication system to which the present disclosure is applied.

[0056] Reference Figure 2 , the radio protocols of the next generation mobile communication system include NR Service Data Adaptation Protocol (SDAP) 2-01 and 2-45, NR Packet Data Convergence Protocol (PDCP) 2-05 and 2-40, NR Radio Link Control (RLC) 2-10 and 2-35, and NR MAC 2-15 and 2-30 at UE and NR gNB respectively.

[0057] The main functions of NR SDAP 2-01 and 2-45 may include some of the following functions.

[0058] -Transmission of user plane data - Mapping between QoS flows and Data Radio Bearers (DRBs) for both DL and UL - Marking QoS Flow ID in both DL and UL packets - Reflective QoS flow to DRB mapping for UL SDAP protocol data units (PDUs).

[0059] For SDAP layer devices, the UE may be configured with a header or a function of whether to use the SDAP layer device for each PDCP layer device, for each bearer or for each logical channel through a radio resource control (RRC) message, and if the SDAP header is configured, the 1-bit non-access layer (NAS) reflection QoS configuration indicator and the 1-bit AS reflection QoS configuration indicator of the SDAP header may indicate that the UE updates or reconfigures the mapping information of the QoS flow and the data bearer in UL and DL. The SDAP header may include QoS flow ID information indicating QoS. QoS information can be used as data processing priority, scheduling information, etc. to support seamless services.

[0060] The main functions of NR PDCP 2-05 and 2-40 may include some of the following functions.

[0061] -Header compression and decompression: Robust Header Compression (ROHC) only -Transmission of user data - Sequential delivery of upper layer PDUs - Out-of-order delivery of upper layer PDUs - Reordering of received PDCP PDUs - Duplicate detection of lower layer SDU -Retransmission of PDCP SDU -Encryption and decryption - Timer based SDU discard in uplink.

[0062] The reordering of the NR PDCP layer device means a function of reordering the PDCP PDU received from the lower layer based on the PDCP sequence number (SN), and may include a function of sending the reordered data to a higher layer, or may include a function of directly sending data without considering the order, a function of reordering and recording lost PDCP PDUs, a function of sending a status report of lost PDCP PDUs to the transmitting side, and a function of requesting retransmission of lost PDCP PDUs.

[0063] The main functions of NR RLC 2-10 and 2-35 may include some of the following functions.

[0064] -Transmission of upper layer PDU - Sequential delivery of upper layer PDUs - Out-of-order delivery of upper layer PDUs - Error correction through Automatic Repeat Request (ARQ) - Concatenation, segmentation and reassembly of RLC SDU - Re-segmentation of RLC data PDUs - Reordering of RLC data PDUs - Duplicate detection -Protocol error detection -RLC SDU discarded -RLC re-establishment.

[0065] The sequential delivery of the NR RLC layer device means a function of sequentially transmitting the RLC SDU received from the lower layer to the higher layer. If an initial RLC SDU is divided into a plurality of RLC SDUs and is received, the sequential delivery of the NR RLC layer device may include a function of reassembling and transmitting them, a function of reordering the received RLC PDU based on the RLC SN or PDCP SN, a function of reordering and recording the lost RLC PDU, a function of sending a status report of the lost RLC PDU to the transmitting side, and a function of requesting retransmission of the lost RLC PDU. If there is a lost RLC SDU, the sequential delivery of the NR RLC layer device may include a function of sequentially transmitting only the RLC SDU before the lost RLC SDU to the higher layer, or if there is a lost RLC SDU but the specified timer expires, it may include a function of sequentially transmitting to the higher layer all RLC SDUs received before the timer starts, or if there is a lost RLC SDU but the specified timer expires, it may include a function of sequentially transmitting to the higher layer all RLC SDUs received so far. In addition, the RLC PDUs may be processed in their reception order (in arrival order, regardless of sequence number or SN), transmitted to the PDCP layer device with out-of-order delivery, and segments stored in a buffer or to be received may be received and reconstructed into a complete RLC PDU, and then processed and transmitted to the PDCP layer device. The NRRLC layer may not include a cascading function, and the function may be performed in the NR MAC layer or may be replaced by a multiplexing function of the NR MAC layer.

[0066] Out-of-order delivery of the NR RLC layer device means a function of directly transmitting RLC SDUs received from a lower layer to a higher layer regardless of the order, and if an initial RLC SDU is divided into multiple RLC SDUs and received, it may include a function of reassembling and transmitting them, and may include a function of storing and sorting the RLC SN or PDCP SN of the received RLC PDU and thus recording the lost RLC PDU.

[0067] NR MAC 2-15 and 2-30 can be connected to multiple NR RLC layer devices configured in one UE, and the main functions of NR MAC may include some of the following functions.

[0068] - Mapping between logical channels and transport channels -Multiplexing / demultiplexing of MAC SDU -Dispatch information report - Error correction via Hybrid ARQ (HARQ) - Priority handling between logical channels of a UE - Prioritization between UEs through dynamic scheduling -Multimedia Broadcast Multicast Service (MBMS) service identification -Transmission format selection -filling.

[0069] NR PHY 2-20 and 2-25 can channel encode and modulate upper layer data and convert the data into OFDM symbols and transmit the OFDM symbols through a wireless channel, or demodulate OFDM symbols received through a wireless channel and channel-decode the OFDM symbols and transmit them to an upper layer.

[0070] Figure 3 A diagram showing another next-generation mobile communication system structure to which the present disclosure is applied.

[0071] Reference Figure 3 , a cell served by a beam-based operated NR gNB 3-05 may include a plurality of transmit receive points (TRPs) 3-10, 3-15, 3-20, 3-25, 3-30, 3-35, and 3-40. TRPs 3-10 to 3-40 represent blocks in which some functions of transmitting and receiving physical signals in an existing NReNB are separated and include multiple antennas. The NR gNB 3-05 may be represented as a central unit (CU), and the TRP may be represented as a distributed unit (DU). The functions of the NR gNB 3-05 and the TRP may be configured by separating each layer from the PDCP / RLC / MAC / PHY layer as shown in 3-45. That is, the TRP may have only the PHY layer and perform the functions of the corresponding layers 3-15 and 3-25, the TRP may have only the PHY layer and the MAC layer and perform the functions of the corresponding layers 3-10, 3-35 and 3-40, and the TRP may have only the PHY layer, the MAC layer and the RLC layer and perform the functions of the corresponding layers 3-20 and 3-30. Specifically, TRP 3-10 to TRP 3-40 may use beamforming technology for sending and receiving data by generating narrow beams in several directions using multiple transmit and receive antennas. The UE 3-50 accesses the NR gNB 3-05 and the external network via the TRP 3-10 to TRP 3-40. The NR gNB 3-05 collects and schedules status information such as the buffer status, available transmission power status and channel status of the UE to serve the user, and supports the connection between the UE and the CN, specifically, the connection between the access and mobility management function (AMF) / session management function (SMF) 3-50.

[0072] In the present disclosure, TRP is based on structures 3-15 and 3-25 having only a PHY layer to perform the functions of the corresponding layers.

[0073] Improvements in MIMO operations in next-generation mobile communication systems (specifically, in frequency range 2 (FR2) using beams to transmit data) require methods for measuring and reporting multiple beams, methods for selecting and using the optimal beam for data transmission and reception, methods for measuring and recovering from beam failures of current beams, and the like.

[0074] Hereinafter, the present disclosure basically explains the above methods and additionally proposes their specific operations. Specifically, the present disclosure provides a technique for improving operations related to beam failure detection (BFD) and beam failure recovery (BFR).

[0075] Conventional BFD and BFR can be divided into special cell (SpCell) BFR and secondary cell (SCell) BFR, and the two methods jointly perform cell-specific BFD / BFR. Depending on the cell of BFD / BFR, the two methods are different in their subsequent operations, which can be briefly described as follows.

[0076] -SCell BFR *If BFD occurs in a specific SCell, the UE sends a BFR MAC CE via UL resources * If the UL resources for transmitting the BFR MAC CE are insufficient, a Scheduling Request (SR) for BFR transmission is triggered (SR configuration and Physical Uplink Control Channel (PUCCH) resources are configured at the gNB on a cell basis) *BFR MAC CE configuration: SCell information of beam failure, candidate beam indicator, candidate beam identifier * The BFR procedure is completed if a Physical Downlink Control Channel (PDCCH) addressed by the Cell (C)-Radio Network Temporary Identifier (RNTI) is received -SpCell BFR * If BFD occurs in the SpCell, the UE triggers a random access procedure and sends messageA (msgA) or msg3 including BFR MAC CE *BFR MAC CE configuration: SpCell beam failure indicator, candidate beam indicator, candidate beam identifier * If a PDCCH addressed by C-RNTI is received, the BFR procedure is completed The following embodiments of the present disclosure illustrate BFD / BFR operations at multiple TRPs and refer to SCell BFD / BFR and SpCell BFD / BFR for comparison. Some of the aforementioned operations may be omitted in the reference for operation comparison, but the application of these operations is specified at the beginning of the specification of the present disclosure.

[0077] In the present disclosure, FR1 indicates 410 MHz to 7125 MHz in which the NR system operates, and FR2, which is a method of transmitting wireless resources using directional beams, covers all of 24250 MHz to 52600 MHz and extended FR2 52600 MHz to 71000 MHz.

[0078] Figure 4 A diagram showing a scenario of cell-level and TRP-level beam failure detection / recovery procedures in a next-generation mobile communication system to which the present disclosure is applied.

[0079] exist Figure 4 In the conventional cell-level BFD / BFR scenario ( Figure 4 A (Case 1)) and TRP-level BFD / BFR scenario ( Figure 4 Both scenarios may include multiple TRPs, but the cell-level BFD / BFR scenario performs BFD / BFR based on cells, while the TRP-level BFD / BFR scenario performs BFD / BFR based on TRPs.

[0080] First, the cell-level BFD / BFR scenario A will be briefly summarized as follows.

[0081] The first TRP 4-05 and the second TRP 4-10 may exist in one service cell, and the UE 4-15 may perform multi-TRP operation according to the base station configuration. In this case, the multi-TRP operation means UL / DL transmission and reception (PDCCH / physical downlink shared channel (PDSCH) / PUCCH / physical uplink shared channel (PUSCH) resource transmission and reception) via multiple TRPs, and may include one or more improvements, such as transmission configuration indicator (TCI) state configuration, PDSCH transmission based on a single downlink control information (DCI) through multiple TRPs, and PDSCH transmission based on multiple DCIs via multiple TRPs.

[0082] In addition, beam configuration through multiple TRPs may be applied to configure cell-level BFD / BFR, and the UE performs its operation according to the corresponding configuration. That is, a resource list (e.g., a list of BFD reference signals (RS)) for serving cell-level / cell BFD may be provided, and the UE monitors the BFD resource set configured for BFD in the corresponding serving cell. Moreover, a candidate beam RS list is also provided to the UE together with the configuration so that the UE can report available beams in the BFR report. Reference Figure 4 , among the BFD resources 4-20 to 4-25 configured for the UE, even if a beam failure occurs in each of the beams 4-23, 4-24, and 4-25 allocated to a specific TRP (herein, the second TRP 4-10), BFR is not triggered. Figure 4 Among the beams 4-20, 4-21 and 4-22 of the first TRP 4-05 shown in the figure, one beam 4-21 is valid, so in view of the corresponding service cell, there is a valid beam, and accordingly, the service is provided through the corresponding beam without triggering BFR.

[0083] In conventional systems, only cell-level BFD and BFR are allowed, but according to TRP-level BFD and BFR, if beam failure is detected in each beam of a specific TRP, BFD is reported to the gNB for the TRP level.

[0084] That is, the first TRP 4-30 and the second TRP 4-35 may exist in one service cell, and the UE 4-40 may perform multi-TRP operation according to the base station configuration. The present disclosure shows a scenario in which multiple TRPs exist in one service cell, but in this scenario the TRPs may belong to different cells. That is, the first TRP may belong to the first service cell, and the second TRP may belong to the second service cell. Unlike the service cell level / unit BFD / BFR scenario, the TRP level / unit BFD / BFR scenario can configure the BFD resources to be monitored separately by each TRP and the candidate beam RS list.

[0085] -TRP 1 dedicated BFD RS list, candidate beam RS list.

[0086] -TRP 2 dedicated BFD RS list, candidate beam RS list.

[0087] The UE monitors the BFD resources configured per TRP independently and triggers TRP-level BFR if all BFD RS resources of a particular TRP fail. Figure 4, among the BFD resources 4-45 to 4-50 configured for the UE, if a beam failure occurs in each beam 4-48, 4-49, and 4-50 assigned to a specific TRP (herein, the second TRP 4-35), a TRP-level BFR is triggered. Figure 4 Among beams 4-45, 4-46, and 4-47 of the first TRP 4-30 shown in FIG, one beam 4-46 is valid, and the valid beam exists in the corresponding first TRP, and accordingly, the service is provided through the corresponding beam without triggering BFR. In contrast, with respect to the second TRP, the UE reports the failure of each beam of the corresponding TRP to the gNB, and if a valid candidate beam RS is detected in the corresponding process, it is sent together. Therefore, the gNB can improve the transmission and reception of the terminal through the TRP-level beam.

[0088] Figure 5 A diagram showing a cell-level BFD / BFR process using multiple TRPs adopted in an NR system referenced in this disclosure. Figure 5 Corresponding to Figure 4 The specific process of the cell-level BFD / BFR scenario of scenario A is described in.

[0089] In operation 5-05, a UE 5-01 in idle mode RRC_IDLE is camping (or residing) on ​​a corresponding gNB 5-02 to search for a suitable cell, and in operation 5-10, accesses the gNB or primary cell (PCell) 5-02 because data transmission occurs. In this document, the gNB 5-02 may include multiple TRPs 5-03 and 5-04. In idle mode, no data is transmitted without connecting to the network for UE power saving, and it is necessary to transition to connected mode RRC_CONNECTED for data transmission. UE camping as described above means that the UE is present in the corresponding cell and receives a paging message to determine whether data is received in DL. If the gNB 5-02 is successfully accessed, the UE transitions to connected mode RRC_CONNECTED, and the UE in connected mode can send data to the gNB and receive data from the gNB.

[0090] In operation 5-15, the gNB and the UE in RRC_CONNECTED mode perform a process of acquiring UE capabilities. That is, the gNB sends a UE capability inquiry message to the UE, and performs UE capability inquiry by screening the UE capabilities required by the corresponding gNB. The UE receives the UE capabilities supported by the UE within the inquiry range of the corresponding gNB, and sends them to the gNB using a UE capability information message.

[0091] In operation 5-20, the gNB sends an RRC reconfiguration message including configuration information of the corresponding gNB to the UE. The RRC message may include the configurations of the cell-level BFD / BFR RadioLinkMonitoringConfig, beamFailureRecoverySCellConfig, and beamFailureRecoveryConfig, and provide the associated measurement resource configuration and TCI state configuration.

[0092] In operation 5-25, the UE monitors the BFD resources configured for the BFD of the corresponding serving cell by applying the list of BFD RS configurations for the serving cell level / unit BFD received in the RRC message. In operation 5-30, if it is determined that all monitored BFD RSs fail (if the corresponding BFD RS indicates beam failure exceeding beamFailureInstanceMaxCount when beamFailureDetectionTimer is running), the UE triggers BFR.

[0093] In operation 5-35, if the UL resources for transmitting the SCell BFR MAC CE are insufficient, the UE sends an SR to the gNB and receives a UL grant for the request. If the SCell BFR is not triggered in the corresponding operation but the SpCell (PCell or primary secondary cell group (SCG) cell (PSCell)) BFR is triggered, random access is triggered in the corresponding operation. If the UL resources for carrying the SCell BFR MAC CE from the UE exist, the operation is omitted.

[0094] In operation 5-40, the UE generates a BFR MAC CE including the triggered BFR information and transmits it to the gNB. If the SpCell (PCell or PSCell) BFR is triggered, the UE sends msgA (for 2-step random access) / msg3 (for 4-step random access) including the BFR MAC CE in the random access procedure. In operation 5-45, the gNB may reconfigure the appropriate beam by referring to the BFR MAC CE information received from the UE. This operation may be performed by a TCI state configuration change in an RRC message and a DL TCI state change via a MAC CE. In operation 5-50, the UE performs data transmission and reception with the gNB through the beam restored via the reconfiguration.

[0095] Figure 6 A diagram showing a TRP-level BFD / BFR process using multiple TRPs employed in a NR system as applied to the present disclosure. Figure 6 Corresponding to Figure 4The specific procedures for the TRP-level BFD / BFR scenario for Scenario B are described in .

[0096] In operation 6-05, the UE 6-01 in idle mode RRC_IDLE is camping (or residing) on ​​the corresponding gNB 6-02 to search for a suitable cell, and in operation 6-10, the gNB or PCell 6-02 is accessed because data transmission occurs. In this article, the gNB 6-02 may include multiple TRPs, but as Figure 6 Each serving cell shown in 6-02 may include each TRP (cell 1-TRP 1, 6-02; cell 2-TRP 2, 6-03), and perform inter-cell multi-TRP operation. In idle mode, no data is transmitted without connecting to the network for UE power saving, and it is necessary to transition to connected mode RRC_CONNECTED for data transmission. Camping means that the UE exists in the corresponding cell and receives a paging message to determine whether data is received in DL. If the gNB 6-02 is successfully accessed, the UE transitions to connected mode RRC_CONNECTED, and the UE in connected mode can send data to the gNB and receive data from the gNB.

[0097] In the RRC_CONNECTED mode, in operations 6-15, the gNB and the UE perform a procedure for acquiring UE capabilities. That is, the gNB sends a UE capability inquiry message to the UE, and performs UE capability inquiry by screening the UE capabilities required by the corresponding gNB. The UE receives the UE capabilities supported by the UE within the inquiry range of the corresponding gNB, and sends them to the gNB using a UE capability information message. In this operation, if BFD is performed via multiple TRPs, the UE may indicate through a MAC CE whether an operation of activating a BFDRS set is supported. In this operation, the UE may indicate the maximum number of BFD RS resources configurable per TRP, and thus indicate the capability of activating a BFD RS set in BFD through a MAC CE. If the UE does not indicate the corresponding capability, the gNB may only configure a maximum of two BFD RS resources per TRP for the UE.

[0098] In operation 6-20, the gNB sends an RRC reconfiguration message including configuration information of the corresponding gNB to the UE. The RRC message may include the configurations of TRP-level BFD / BFR RadioLinkMonitoringConfig, beamFailureRecoverySCellConfig, and beamFailureRecoveryConfig, and gives the associated measurement resource configuration and TCI state configuration. Specifically, the corresponding operation is different from Figure 5, because BFD / BFR is managed per TRP, and RadioLinkMonitoringConfig and BeamFailureRecoveryRSConfig can be configured for multiple TRPs (two TRPs), as described below.

[0099] - Independent BFD RS set configuration for two TRPs (BFD RS set for TRP1, BFD RS set for TRP2; failureDetectionSet1, failureDetectionSet2 in RadioLinkMonitoringConfig).

[0100] *BeamFailureDetectionSet-r17 includes the BFD RS resources configured per TRP and includes the timer and counter values ​​required to monitor BFD and trigger BFR.

[0101] *BeamLinkMonitoringRS-r17 provides the actual configured BFD RS, which may indicate synchronization signal block (SSB) resources and channel state information (CSI) RS resources, and may include an identifier for identifying the corresponding resources. Up to 64 resources may be configured according to UE capabilities (to be described in operations 10-15).

[0102] *If the BFD RS set of two TRPs is configured, the existing cell-level BFD RS configuration may not be provided (the following configuration in ASN.1 may be conditional, and the corresponding condition may be added. Alternatively, its corresponding description may be added to the field description.).

[0103] -BeamFailureRecoveryRSConfig of two TRPs, including candidate beam RS list information (candidateBeamRSList, candidateBeamRSList2).

[0104] In operation 6-25, the gNB may send a BFD RS activation / update MAC CE to the UE to indicate the update information configured with the resource list of the TRP level / unit BFD (the list of BFD RSs of TRP1 and TRP2) configured with the RRC. MAC CE transmission is always possible, and it is necessary to clarify the UE operation before receiving the corresponding MAC CE on the UE side. The following embodiment proposes its specific operation.

[0105] The features of the present disclosure are applied to the corresponding operations. If a MAC CE is received in this operation, the UE initializes its BFR-related parameter BFI_COUNTER value to 0 and cancels the BFR of the ongoing BFD RS set. This is to initialize the BFR process of the ongoing BFD RS before receiving the MAC CE, because the BFDRS applied to measure the BFD of the corresponding TRP is updated. If a BFD RS update MAC CE is received, the UE applies it after receiving "X" time slots from the time slot of the transport block (TB) including the corresponding MAC CE. In this article, "X" time slots can be a value defined in the standard and can be a value given by RRC configuration. The value can be given in an explicit time unit other than a symbol or a time slot (e.g., milliseconds).

[0106] In operation 6-30, the UE monitors the BFD resources per TRP configured for BFD of a specific TRP by applying the resource list for TRP-level / cell BFD (list of BFD RSs for TRP1 and TRP2) received in the RRC message or MAC CE. In operation 6-35, if failure of all BFD RSs monitored per TRP is determined (if the corresponding BFD RS indicates beam failure exceeding beamFailureInstanceMaxCount while beamFailureDetectionTimer is running), the UE triggers BFR for the corresponding TRP. In operation 6-40, if the UL resources for transmitting the BFR MAC CE per TRP are insufficient, the UE sends an SR to the gNB and receives a UL grant for the request. If SCell BFR is not triggered in the corresponding operation but SpCell (PCell or PSCell) BFR is triggered, random access is triggered in the corresponding operation. If UL resources for carrying the BFR MAC CE per TRP from the UE exist, this operation is omitted.

[0107] In operation 6-45, the UE generates a BFR MAC CE (hereinafter, used together with a multi-TRP (mTRP) BFR MAC CE) including BFR information of the triggered TRP, and transmits it to the gNB. If the SpCell (PCell or PSCell) BFR is triggered, the UE sends msgA (for 2-step random access) / msg3 (for 4-step random access) including an mTRP BFR MAC CE in the random access procedure. In operation 6-50, the gNB may reconfigure an appropriate beam by referring to the BFR MAC CE information received from the UE. This operation may be performed by a TCI state configuration change in an RRC message and a DL TCI state change via a MAC CE. In operation 6-55, the UE performs data transmission and reception with the gNB by using the beam restored via the reconfiguration.

[0108] In operation 6-60, because the BFD RS configuration to be measured by the UE per TRP may vary according to the changed beam configuration, the gNB retransmits the MAC CE for BFD RS activation / update to the UE. If the MAC is received in this operation, the UE initializes its BFR-related parameter BFI_COUNTER value to 0 and cancels the BFR of the ongoing BFD RS set (or if the beam change is received from the gNB in ​​operation 6-50, the value BFI_COUNTER is initialized to 0 and the BFR of the ongoing BFD RS set is canceled). This is to initialize the BFR process of the ongoing BFD RS before receiving the MAC CE, because the BFD RS applied to measure the BFD of the corresponding TRP is updated. If the BFD RS update MAC CE is received, the UE applies it after receiving "X" time slots from the time slot of the TB including the corresponding MAC CE. Herein, "X" time slots may be a value defined in the standard and may be a value given by RRC configuration. The value may be given in an explicit time unit (e.g., milliseconds) other than a symbol or a time slot. In a base station implementation, the beam update indication MAC CE 6-50 and the BFD update MAC CE 6-60 may be included in one MAC PDU and transmitted.

[0109] In operation 6-65, the UE monitors the updated BFD RS per TRP and then performs the BFD / BFR process. That is, the UE performs operations after operation 6-35.

[0110] The present disclosure provides multiple (up to 64) BFD RS configurations to be measured by the UE per TRP through RRC configuration, and then dynamically activates and updates up to two BFD RSs to be measured by the UE for BFD per TRP through MAC CE. Specifically, the BFD RS resources per TRP provided through RRC configuration are different according to the UE capability (BFD RS set activation MAC CE operation support). That is, if the UE has the capability of BFD RS set activation MAC CE operation support, the gNB can configure the UE with up to 64 BFD RSs to be measured per TRP for BFD, and if the UE does not have the capability of BFD RS set activation MAC CE operation support, the gNB can configure the UE with up to two BFD RSs to be measured per TRP for BFD. In this case, the UE applies and monitors the BFD RS resources configured with RRC.

[0111] In contrast, if the UE has the capability of BFD RS set activation MAC CE operation support and the gNB supports it and configures multiple BFD RS resources, the UE can identify the resources to be actually monitored by receiving activation via MAC CE. However, the following issues should be considered in addition.

[0112] 1. Question 1: It is necessary to clarify when the BFD RS Set Activation / Update MAC CE (or BFD RS Indication MAC CE) is sent.

[0113] - For example, whether to send MAC even if the BFD RS sets configured for two TRPs through RRC are two or less.

[0114] - For example, whether to send MAC even if only one BFD RS set is configured for two TRPs through RRC.

[0115] 2. Question 2: Whether and how the UE performs BFD before receiving the BFD RS set activation / update MAC CE.

[0116] Hereinafter, embodiments of the present disclosure propose explicit UE operations for the above two problems, thereby clarifying the UE operations. In addition, the present disclosure provides the following solutions to the above problems. First, a solution to Problem 1 is described.

[0117] 1. Solution 1-1: Although the UE supports BFD RS indication MAC CE, the gNB sends the corresponding MAC CE only if the number of BFD RSs in any BFD RS set configured per TRP exceeds 2.

[0118] - For example, if more than two (>2) BFD RSs are configured in one BFD RS set and two or less (<=2) BFD RSs are configured in another BFD RS set, signaling related to BFD RS indication of the BFD RS set configured with two or less BFD RSs is omitted from the MAC CE. That is, with respect to the BFD RS set configured with two or less BFD RSs through RRC, Figure 7 Skip the octet including the BFD RS ID in the MAC CE format described in (Skip the octet including the BFD RS ID of a set with <= 2 BFD RSs in the MAC CE).

[0119] - In this case, the UE considers that the BFD RSs of the omitted BFD RS set are activated.

[0120] 2. Solution 1-2: If the UE supports BFD RS indication MAC CE, the gNB sends the corresponding MAC CE only if the number of BFD RS in any BFDRS set configured per TRP exceeds 1.

[0121] - For example, if more than 1 (>1) BFD RSs are configured in one BFD RS set and one BFD RS is configured in another BFD RS set, signaling related to BFD RS indication of the BFD RS set configured with one BFD RS is omitted from the MAC CE. That is, regarding the BFD RS set configured with one BFD RS through RRC, Figure 7 The octet including the BFD RS ID in the MAC CE format is omitted in the MAC described in (the octet including the BFD RS ID of the set with 1 BFD RS is skipped in the MAC CE).

[0122] - In this case, the UE considers that the BFD RSs of the omitted BFD RS set are activated.

[0123] -The difference from solution 1-1 is that although two BFD RSs are initially configured through RRC, the gNB can indicate only one BFD RS through MAC CE, and therefore, even if the number of BFD RSs of the BFD RS set exceeds 1, the UE determines the BFD RS to be monitored by receiving MAC CE.

[0124] 3. Solution 1-3: If the UE supports BFD RS indication MAC CE, the gNB always sends the corresponding MAC CE.

[0125] - That is, regardless of the number of BFD RSs in the BFD RS set, the UE always waits for the MAC CE.

[0126] In this case, if the gNB configures two or less BFD RSs in the BFD RS set, a solution is required for the UE to determine whether to wait for MAC CE. For example, the RRC configuration can provide a 1-bit indicator.

[0127] Next, a solution to Problem 2 is described.

[0128] 1. Solution 2-1: The UE does not perform BFD operation until BFD RS Indication MAC CE is received from the gNB. That is, the UE performs BFD operation after receiving BFD RS Indication MAC CE and BFD RS is indicated.

[0129] - In this case, a time gap may occur between the RRC configuration and the MAC CE signaling.

[0130] - In an embodiment, the gNB may transmit the RRC configuration message and the BFD RS indication MAC CE in the same MAC PDU. However, due to the difference in RRC processing time and MAC CE processing time, the received messages may be stored in the UE's buffer and processed after each message is decoded.

[0131] 2. Solution 2-2: RRC configuration indicates the BFD RS to be initially monitored by the UE.

[0132] - For example, one or two BFD RSs with low indexes in the BFD RS list per BFD RS set provided by the initial RRC configuration are set as BFD RSs to be initially monitored.

[0133] - In this case, corresponding instructions can be added to the specification. In this case, the UE operation can be clearly defined at all times by adding explicit operations in the RRC specification.

[0134] 3. Solution 2-3: UE monitors the activated TCI state with BFD RS.

[0135] - That is, its operation is the same as the case where BFD RS is not configured. In this case, the relevant UE operation can always be clearly defined.

[0136] Figure 7 A diagram showing the MAC CE structure for BFD RS activation / update per TRP referenced in this disclosure.

[0137] The UE may perform BFD RS activation and update per TRP by providing specific resource information of the BFD RS to be monitored by the UE in the MAC CE for BFD RS activation and update per TRP.

[0138] like Figure 6 The following RRC configuration is applied as mentioned above.

[0139] - Separate BFD RS set configuration for two TRPs (BFD RS set for TRP1, BFD RS set for TRP2; failureDetectionSet1, failureDetectionSet2 in RadioLinkMonitoringConfig).

[0140] *BeamFailureDetectionSet-r17 includes the BFD RS resources configured per TRP and includes the timer and counter values ​​required to monitor BFD and trigger BFR.

[0141] *BeamLinkMonitoringRS-r17 provides the actually configured BFD RS, which may indicate SSB resources and CSIRS resources, and may include an identifier beamLinkMonitoringRS-id-r17 for identifying the corresponding resource. A maximum of 64 resources may be configured according to UE capabilities (to be described in operations 10-15).

[0142] *If the BFD RS set of two TRPs is configured, the existing cell-level BFD RS configuration may not be provided (the following configuration in ASN.1 may be conditional, and the corresponding condition may be added. Alternatively, its corresponding description may be added to the field description.).

[0143] -BeamFailureRecoveryRSConfig of two TRPs, including candidate beam RS list information (candidateBeamRSList, candidateBeamRSList2).

[0144] Now, it will Figure 7 The BFD RS activation / update MAC CE structure for multiple TRPs is described in. Figure 7 The BFD RS activation / update MAC CE for multiple TRPs proposed in may include at least the following fields.

[0145] - Reserved bits (7-05, 7-20, 7-40): Detailed description of reserved bits is omitted in the figure - Serving Cell ID (5 bits; 7-10): Serving cell identifier to which the information indicated in the corresponding MAC CE is applied - BWP ID (2 bits; 7-15): BWP identifier of the serving cell to which the information indicated in the corresponding MAC CE applies -S (1 bit; 7-25, 7-45): Identifier indicating whether there is a second activated BFD RS ID. If the corresponding bit indicates 1, there are two activated BFD RS IDs for one BFD RS set. If the corresponding bit indicates 0, there is one activated BFD RS ID for one BFD RS set.

[0146] - BFD RS ID of TRP1 (7-30, 7-35): A BFD RS resource identifier that actually indicates UE monitoring among BFD RS resources for TRP1 configured through RRC and mapped to beamLinkMonitoringRS-Id-r17 configured in RRC. A maximum of two BFD RS resources are indicated.

[0147] - BFD RS ID of TRP2 (7-50, 7-55): A BFD RS resource identifier that actually indicates UE monitoring among BFD RS resources used to configure TRP2 through RRC and mapped to beamLinkMonitoringRS-id-r17 configured in RRC. A maximum of two BFD RS resources are indicated.

[0148] The BFD RS activation / update MAC CE for multiple TRPs described in the figure has a new enhanced logical channel identifier (eLCID) value and can be distinguished by the eLCID determined in the MAC PDU subheader. In addition, the BFDRS activation / update MAC CE for multiple TRPs basically includes one or two BFD RS sets.

[0149] Figure 8 A diagram showing a method of performing BFD RS monitoring if a terminal receives a BFD RS set per TRP and a BFDRS indication MAC CE from a base station according to an embodiment of the present disclosure.

[0150] The embodiments herein adopt solutions 1-1, 1-2, 1-3 and solution 2-1 for Problem 1 and Problem 2 to be solved respectively in the present disclosure.

[0151] In operation 8-05, the UE sends UE capabilities to the gNB. That is, the gNB first sends a UE capability inquiry message to the UE, and requests UE capabilities by screening the UE capabilities required by the gNB. The UE receives UE capabilities supported by the UE within the inquiry range of the corresponding gNB, and sends them to the gNB using a UE capability information message. In this operation, if BFD is performed via multiple TRPs, the UE can indicate whether an operation of activating a BFD RS set through a MAC CE is supported (BFD RS indicates MAC CE). In this operation, the UE can indicate the maximum number of BFD RS resources configurable per TRP, and thus if BFD is performed, it can indicate the capability for activating the BFD RS for actual monitoring by receiving a BFD RS set via a MAC CE. If the UE does not indicate the corresponding capability, the gNB can provide the UE with a maximum of two BFD RS resources per TRP via RRC configuration. That is, the BFD RS indicates that the MAC CE is not used.

[0152] In operations 8-10, the UE in RRC connected mode receives an RRC reconfiguration message including configuration information of the corresponding gNB from the gNB. The RRC message may include the configuration of the BFD / BFR-based TRP (e.g., RadioLinkMonitoringConfig, beamFailureRecoverySCellConfig, and beamFailureRecoveryConfig), and give the associated measurement resource configuration and TCI state configuration. Fig.10 The details related to the configuration are described in . Specifically, operations 8-10 configure multiple BFD RS sets (i.e., multiple TRPs) and BFD RSs of the corresponding BFD RS set among the BFD / BFR related configurations of the multiple TRPs. The number of BFD RSs that can be configured in the corresponding BFD RS set can be determined by the gNB in ​​association with the UE capabilities. In addition, an indicator (1 bit) indicating whether the gNB uses the BFD RS indication MAC CE can be added to the corresponding message. As discussed in Question 1, if the gNB provides two or less BFD RSs for each BFDRS set through RRC configuration, the UE may not understand whether the corresponding gNB applies the BFD RS indication MAC CE. Because the BFD monitoring operation may differ on the UE side depending on whether the BFD RS indication MAC CE is applied, the corresponding 1-bit indicator can be effectively used.

[0153] In operation 8-15, the UE receives a BFD RS indication MAC CE from the gNB. A feature of the embodiments herein is that the UE does not perform BFD RS monitoring until a corresponding operation, that is, until a BFD RS indication MAC CE is received. All solutions 1-1, 1-2, and 1-3 can be applied to problem 1, and the operation under the case of applying solution 2-1 is briefly described.

[0154] 1. Case 1: If solution 1-1 is applied and solution 2-1 is applied.

[0155] -More than two BFD RSs are configured in at least one or more BFD RS sets among the BFD RS sets in each TRP through RRC configuration, and the UE does not monitor the BFD RS resources configured by RRC, but monitors the BFD RS after receiving the BFD RS indication MAC CE.

[0156] - If two or less (<=2) BFD RSs are configured in the BFD RS set, the signaling in the MAC CE related to the BFD RS indication of the BFD RS set configured with two or less BFD RSs is omitted, so that although the corresponding content is omitted, the BFD RS resources configured in the RRC are monitored when the MAC CE is received. Alternatively, the UE can monitor the corresponding resources based on the RRC configuration.

[0157] 2. Case 2: If solution 1-2 is applied and solution 2-1 is applied.

[0158] -More than one BFD RS is configured in at least one or more BFD RS sets among the BFD RS sets in each TRP through RRC configuration, and the UE does not monitor the BFD RS resources configured by RRC, but monitors the BFD RS after receiving the BFD RS indication MAC CE.

[0159] - If one BFD RS is configured in the BFD RS set, the signaling in the MAC CE related to the BFD RS indication of the BFD RS set configured with one BFD RS is omitted, so that although the corresponding content is omitted, the UE also monitors the BFD RS resources configured in the RRC when receiving the MAC CE. Alternatively, starting from the RRC configuration, the corresponding resources can be monitored.

[0160] 3. Case 3: If solution 1-3 is applied and solution 2-1 is applied.

[0161] -The UE does not monitor the BFD RS resources configured by RRC, but monitors the BFD RS after receiving the BFD RS indication MAC CE.

[0162] In operation 8-20, the UE monitors the BFD RS resources indicated per TRP in operation 8-15. In this operation, up to two BFD RS resources can be monitored per TRP, and then the BFD RS resources to be monitored can be changed by receiving the BFD RS indication MAC CE. In operation 8-25, if the monitored BFD RS resources meet the BFR triggering condition, the UE triggers the mTRP and generates and reports the mTRP BFR MAC CE to the gNB. Figure 6 The specific operation is provided in.

[0163] Fig. 9 A diagram showing a method of receiving a BFD RS set per TRP and performing BFD RS monitoring before a terminal receives a BFD RS indication MAC CE from a base station according to an embodiment of the present disclosure.

[0164] The embodiments herein adopt solutions 1-1, 1-2 and 1-3 and solutions 2-2 and 2-3 for Problem 1 and Problem 2 to be solved in the present disclosure, respectively.

[0165] In operation 9-05, the UE sends UE capabilities to the gNB. That is, the gNB first sends a UE capability inquiry message to the UE, and requests UE capabilities by screening the UE capabilities required by the corresponding gNB. The UE receives UE capabilities supported by the UE within the inquiry range of the corresponding gNB, and sends them to the gNB using a UE capability information message. In this operation, when performing BFD via multiple TRPs, the UE can indicate whether an operation of activating a BFD RS set is supported through a MAC CE (BFD RS indication MAC CE). In this operation, the UE can indicate the maximum number of BFD RS resources configurable per TRP, and thus if BFD is performed, it can indicate the capability for activating the BFD RS for actual monitoring by receiving a BFD RS set via a MAC CE. If the UE does not indicate the corresponding capability, the gNB can provide the UE with a maximum of two BFD RS resources per TRP via RRC configuration. That is, the BFD RS indication MAC CE is not used.

[0166] In operations 9-10, the UE receives an RRC reconfiguration message including configuration information of the corresponding gNB from the gNB, the RRC message may include the configuration of BFD / BFR based on TRP (e.g., RadioLinkMonitoringConfig, beamFailureRecoverySCellConfig, and beamFailureRecoveryConfig), and gives the associated measurement resource configuration and TCI state configuration. Fig.10 Details related to the configuration are described in . Specifically, the corresponding operation configures multiple BFD RS sets (i.e., multiple TRPs) and the BFDRS of the corresponding BFD RS sets in the BFD / BFR related configuration of multiple TRPs. The number of BFD RSs that can be configured in the corresponding BFD RS set can be determined by the gNB in ​​association with the UE capabilities. In addition, an indicator (1 bit) indicating whether the gNB uses the BFD RS indication MAC CE can be added to the corresponding message. As discussed in Question 1, if the gNB provides two or less BFD RSs for each BFD RS set through RRC configuration, the UE may not understand whether the corresponding gNB applies the BFD RS indication MAC CE. Because the BFD monitoring operation may differ on the UE side depending on whether the BFD RS indication MAC CE is applied, the corresponding 1-bit indicator can be effectively used.

[0167] In operation 9-15, the UE initially monitors some BFD RSs provided per TRP according to the RRC configuration or predefined rules. For example, one or two BFD RSs with low indexes in the BFD RS list of each BFD RS set provided by the initial RRC configuration are set as the initially monitored BFD RSs. Corresponding instructions can be added to the specification, and the UE operation can be clearly defined at all times by adding explicit operations in the RRC. Alternatively, the UE uses the BFD RS to monitor the activated TCI state, as described in solution 2-3. That is, the operation of the UE is the same as when the BFD RS is not configured.

[0168] In operation 9-20, the UE receives a BFD RS indication MAC CE from the gNB. A feature of the embodiments herein is that the UE performs BFD RS monitoring according to a separate rule even if the BFD RS indication MAC CE is not received before the corresponding operation, and also follows this after receiving the BFD RS indication MAC CE. All solutions 1-1, 1-2, and 1-3 can be applied to problem 1, and the operations in the case of applying solutions 2-2 and 2-3 are briefly described.

[0169] 1. Case 1: If solution 1-1 is applied and solutions 2-2 and 2-3 are applied.

[0170] -More than two BFD RSs are configured in at least one or more BFD RS sets among the BFD RS sets of each TRP through RRC configuration, and the UE monitors the BFD RS resources configured by RRC, and monitors the BFD RS indicated after receiving the BFD RS indication MAC CE.

[0171] - If two or less (<=2) BFD RSs are configured in the BFD RS set, the signaling related to the BFD RS indication of the BFD RS set configured with two or less BFD RSs is omitted from the MAC CE, so that although the corresponding content is omitted, the BFD RS resources configured in the RRC are monitored when the MAC CE is received. Alternatively, starting from the RRC configuration, the corresponding resources can be monitored.

[0172] 2. Case 1: If solution 1-2 is applied and solutions 2-2 and 2-3 are applied.

[0173] -More than one BFD RS is configured in at least one or more BFD RS sets among the BFD RS sets of each TRP through RRC configuration, and the UE monitors the BFD RS resources configured by RRC, and monitors the BFD RS indicated after receiving the BFD RS indication MAC CE.

[0174] - If one BFD RS is configured in the BFD RS set, the signaling related to the BFD RS indication of the BFD RS set in which one BFD RS is configured in the MAC CE is omitted from the MAC CE, so that the UE monitors the BFD RS resources configured in the RRC when receiving the MAC CE despite the omission of the corresponding content. Alternatively, starting from the RRC configuration, the corresponding resources can be monitored.

[0175] 3. Case 3: If solution 1-3 is applied and solutions 2-2 and 2-3 are applied.

[0176] - The UE monitors the BFD RS resources configured by RRC and monitors the BFD RS indicated after receiving the BFD RS indication MAC CE.

[0177] In operation 9-25, the UE monitors the BFD RS resources per TRP indicated in operation 9-15 / 8-20. In the corresponding operation, up to two BFD RS resources can be monitored per TRP, and then the BFD RS resources to be monitored can be changed by receiving the BFD RS indication MAC CE. In operation 9-30, if the monitored BFD RS resources meet the BFR triggering condition, the UE triggers the mTRP and generates and reports the mTRP BFR MAC CE to the gNB. Figure 6 The specific operation is provided in.

[0178] Fig.10 A diagram showing the operation of a base station to which an embodiment of the present disclosure is applied.

[0179] The gNB may establish an RRC connection state with the UE in operation 10-05, request UE capabilities from the UE in operation 10-10, and receive corresponding UE capability information. The gNB may analyze the UE capabilities received in the above operations and determine whether the corresponding UE supports mTRP BFD / BFR, and obtain the number of BFD RS resources to be monitored. In addition, the gNB identifies whether the UE supports the BFDRS indication MAC CE. If the corresponding UE capabilities are identified, in operation 10-15, the gNB sends an RRC reconfiguration message including cell-level BFD / BFR configuration and TRP-level BFD / BFR configuration to the corresponding UE. The UE receives an RRC reconfiguration message including cell group configuration information and configuration information ServingCellConfig for configuring multiple serving cells. The RRC message includes configuration information PDCCH-Config and PDSCH-config for reception through PDCCH and PDSCH, and the beam configuration for PUCCH resource transmission is also included in PUCCH-config. In more detail, it may include BWP configuration BWP-uplink and BWP-downlink, control resource set (CORESET) configuration, scrambling configuration, TCI state (TCI-State in PDSCH-config) configuration, PUCCH resources and PUCCH resource sets, spatial relationship information, etc. Specifically, the TCI state-related configuration is provided per DL BWP of the serving cell and is included in each PDCCH-Config and PDSCH-config, and the PUCCH resource configuration and beam configuration for corresponding resource transmission are also included in PUCCH-config. PUCCH configuration can configure PUCCH resources, PUCCH resource sets, spatial relationship information, etc.

[0180] In the corresponding operation, multiple TRPs may be configured and may include configurations related to BFD and BFR of the multiple TRPs (eg, RadioLinkMonitoringConfig, beamFailureRecoverySCellConfig, beamFailureRecoveryConfig). In this regard, Figure 6 Specifically, the configuration of cell-level BFD / BFR support in the corresponding operation ( Figure 5) is that BFD / BFR is managed per TRP, so RadioLinkMonitoringConfig and beamFailureRecoverySCellConfig can be configured for multiple (two) TRPs. In addition, the gNB can provide an existing TCI state configuration related to the TCI state, or a unified TCI state configuration can be applied. The unified TCI state configuration is a method of jointly managing beams of multiple cells instead of allocating TCI states on a cell basis, and is a framework for inter-cell beam management. BFD / BFR operations via multiple TRPs can be applied to the two TCI state frameworks in the present disclosure, and the beam index and indication method used in BFD / BFR via TRP vary depending on the configuration applied.

[0181] Although not in Fig.10 As depicted in the figure, but after sending the RRC message, the gNB may send a BFD RS Update MAC CE for the TRP to the UE. If BFD / BFR configuration for the TRP is provided, this may always be specified as in the RRC configuration in the standard to send the BFD RS Indication MAC CE after the RRC configuration message, or in the base station implementation, the corresponding BFD RS Indication MAC CE may be included after the RRC configuration or omitted. If the RRC reconfiguration provides the BFD / BFR configuration for the TRP, specifically, if information or rules are provided to monitor the BFD RS after the UE receives the RRC message, the corresponding BFD RS Indication MAC CE may be omitted.

[0182] In operation 10-20, the gNB may indicate a TCI state change, i.e., a beam change, through a MAC CE according to the beam-level measurement report value received from the UE. Next, if it is necessary to change the BFDRS to be monitored by the UE according to the changed beam, in operation 10-25, the gNB may send a BFD RS update MAC CE of the TRP. Operations 10-20 and 10-25 may be integrated in a base station implementation, and one MAC PDU including two MAC CEs may be sent.

[0183] In operation 10-30, the gNB may receive an mTRP BFR MAC CE from the UE and recognize that BFR occurs at a specific TRP. The MAC CE may be sent during random access (sPCell BFR) or in a connected state (SCell BFR) via uplink resources. The gNB may obtain that BFR occurs at a TRP of a specific serving cell based on the mTRP BFR MAC CE received from the UE, and obtain valid candidate beam information for the corresponding TRP, and thus apply it to the optimal beam change indication for the UE in operation 10-35.

[0184] Fig.11 is a block diagram showing an internal structure of a UE to which the present disclosure is applied.

[0185] Reference Fig.11 , the UE includes a radio frequency (RF) processor 11 - 10, a baseband processor 11 - 20, a storage device 11 - 30, and a controller 11 - 40.

[0186] The RF processor 11-10 performs functions such as signal band conversion and amplification for sending and receiving signals through a wireless channel. That is, the RF processor 11-10 up-converts the baseband signal provided by the baseband processor 11-20 into an RF band signal, transmits the RF band signal via an antenna, and down-converts the RF band signal received through the antenna into a baseband signal. For example, the RF processor 11-10 may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a digital-to-analog converter (DAC), an analog-to-digital converter (ADC), etc. Although Fig.11 Only one antenna is shown in the figure, but the UE may include multiple antennas. The RF processor 11-10 may include multiple RF chains. In addition, the RF processor 11-10 may perform beamforming. For beamforming, the RF processor 11-10 may adjust the phase and magnitude of signals sent and received via multiple antennas or antenna elements. The RF processor 11-10 may perform MIMO and receive several layers when performing MIMO operations.

[0187] The baseband processor 11-20 performs a conversion function between a baseband signal and a bit stream according to the physical layer standard of the system. For example, in data transmission, the baseband processor 11-20 generates a composite symbol by encoding and modulating the transmission bit stream. In data reception, the baseband processor 11-20 recovers the received bit stream by demodulating and decoding the baseband signal provided from the RF processor 11-10. For example, according to OFDM, in data transmission, the baseband processor 11-20 generates a composite symbol by encoding and modulating the transmission bit stream, maps the composite symbol to a subcarrier, and constructs an OFDM symbol by inverse fast Fourier transform (IFFT) and cyclic prefix (CP) insertion. Moreover, in data reception, the baseband processor 11-20 divides the baseband signal provided from the RF processor 11-10 into OFDM symbols, recovers the signal mapped to the subcarrier by FFT, and recovers the received bit stream by demodulating and decoding the signal.

[0188] The baseband processor 11-20 and the RF processor 11-10 send and receive signals as described above. Therefore, the baseband processor 11-20 and the RF processor 11-10 can be referred to as a transmitter, a receiver, a transceiver, or a communicator. In addition, at least one of the baseband processor 11-20 or the RF processor 11-10 may include a plurality of communication modules for supporting a plurality of different wireless access technologies. In addition, at least one of the baseband processor 11-20 and the RF processor 11-10 may include a plurality of communication modules for processing signals in different frequency bands. For example, different wireless access technologies may include a wireless local area network (LAN) (e.g., IEEE 802.11), a cellular network (e.g., LTE), etc. In addition, different frequency bands may include ultra-high frequency (SHF) (e.g., 2.5 GHz or 5 GHz) bands and millimeter wave (e.g., 60 GHz) bands.

[0189] The storage device 11-30 stores data such as basic programs, applications and configuration information for UE operation. Specifically, the storage device 11-30 can store information related to a second access node that performs wireless communication using a second radio access technology. The storage device 11-30 provides the stored data at the request of the controller 11-40.

[0190] The controller 11-40 controls the overall operation of the UE. For example, the controller 11-40 may send and receive signals through the baseband processor 11-20 and the RF processor 11-10. The controller 11-40 records data in the storage device 11-30 and reads data from the storage device 11-30. To this end, the controller 11-40 may include at least one processor. For example, the controller 11-40 may include a communication processor (CP) for performing communication control and an application processor (AP) for controlling a higher layer such as an application program. In addition, the controller 11-40 may also include a multi-connection processor 11-42 for supporting multi-connection.

[0191] Fig.12 A block diagram showing the configuration of an NR gNB according to the present disclosure is shown.

[0192] like Fig.12 As shown in , the gNB includes an RF processor 12-10, a baseband processor 12-20, a backhaul communicator 12-30, a storage device 12-40, and a controller 12-50.

[0193] The RF processor 12-10 performs functions such as signal band conversion and amplification for transmitting and receiving signals through a wireless channel. That is, the RF processor 12-10 up-converts the baseband signal provided by the baseband processor 12-20 into an RF band signal, transmits the RF band signal via an antenna, and down-converts the RF band signal received through the antenna into a baseband signal. For example, the RF processor 12-10 may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, etc. Although in Fig.12 Only one antenna is shown in the figure, but the gNB may also include multiple antennas. The RF processor 12-10 may include multiple RF chains. In addition, the RF processor 12-10 may perform beamforming. For beamforming, the RF processor 12-10 may adjust the phase and magnitude of signals sent and received via multiple antennas or antenna elements. The RF processor 12-10 may perform downlink MIMO operations by transmitting one or more layers.

[0194] The baseband processor 12-20 performs a conversion function between a baseband signal and a bit stream according to the physical layer standard of the first wireless access technology. For example, in data transmission, the baseband processor 12-20 generates a composite symbol by encoding and modulating the transmission bit stream. In data reception, the baseband processor 12-20 recovers the received bit stream by demodulating and decoding the baseband signal provided from the RF processor 12-10. For example, according to OFDM, in data transmission, the baseband processor 12-20 generates a composite symbol by encoding and modulating the transmission bit stream, maps the composite symbol to a subcarrier, and constructs an OFDM symbol by IFFT and CP insertion. Moreover, in data reception, the baseband processor 12-20 divides the baseband signal provided from the RF processor 12-10 into OFDM symbols, recovers the signal mapped to the subcarrier by FFT, and recovers the received bit stream by demodulating and decoding the signal. The baseband processor 12-20 and the RF processor 12-10 send and receive signals as described above. Thus, the baseband processor 12-20 and the RF processor 12-10 may be referred to as transmitters, receivers, transceivers, communicators, or wireless communicators.

[0195] The backhaul communicator 12-30 provides an interface for communicating with other nodes in the network. That is, the backhaul communicator 12-30 converts a bit stream transmitted to another node (eg, a secondary gNB, a core network, etc.) into a physical signal, and converts a physical signal received from another node into a bit stream.

[0196] The storage device 12-40 stores data such as basic programs, applications, and configuration information for the operation of the master gNB. Specifically, the storage device 12-40 may store information of bearers allocated to connected UEs and measurement results reported from connected UEs. The storage device 12-40 may store information for determining whether to provide or stop multiple connections to the UE. The storage device 12-40 provides the stored data at the request of the controller 12-50.

[0197] The controller 12-50 controls the overall operation of the master gNB. For example, the controller 12-50 may send and receive signals through the baseband processor 12-20 and the RF processor 12-10 or the backhaul communicator 12-30. The controller 12-50 records data in the storage device 12-40 and reads data from the storage device 12-40. To this end, the controller 12-50 may include at least one processor. In addition, the controller 12-50 may also include a multi-connection processor 12-52 for supporting multiple connections.

[0198] The method according to the embodiment described in the claims or the specification of the present disclosure may be implemented in software, hardware, or a combination of hardware and software.

[0199] Regarding software, a computer-readable storage medium storing one or more programs (software modules) may be provided. One or more programs stored in a computer-readable storage medium may be configured for execution by one or more processors of an electronic device. One or more programs may include instructions for controlling an electronic device to perform a method according to an embodiment described in the claims or specification of the present disclosure.

[0200] Such programs (software modules, software) may be stored in random access memory, non-volatile memory, including flash memory, read-only memory (ROM), electrically erasable programmable ROM (EEPROM), magnetic disk storage, compact disk (CD)-ROM, digital versatile disk (DVD) or other optical storage device, and magnetic tape cassette. Alternatively, it may be stored in a memory combining part or all of those recording media. Multiple memories may be included.

[0201] Furthermore, the program may be stored in an attachable storage device that is accessible via a communication network such as the Internet, an intranet, a LAN, a wide area LAN (WLAN), or a storage area network (SAN), or a communication network that combines these networks. Such a storage device may access the apparatus that executes the embodiments of the present disclosure through an external port. In addition, a separate storage device on a communication network may access the apparatus that executes the embodiments of the present disclosure.

[0202] In a specific embodiment of the present disclosure, the components included in the present disclosure are expressed in singular or plural form. However, for ease of explanation, singular or plural expression is appropriately selected according to the situation presented, and the present disclosure is not limited to a single component or multiple components, and a component expressed in plural form can be configured as a single component, and a component expressed in singular form can be configured as multiple components.

[0203] At the same time, although specific embodiments have been described in the detailed description of the present disclosure, it will be noted that various changes may be made therein without departing from the scope of the present disclosure. For example, some or all of certain embodiments may be combined with some or all of one or more other embodiments that also correspond to embodiments of the present disclosure. Therefore, the scope of the present disclosure is not limited and defined by the described embodiments, but is limited not only by the scope of the appended claims but also by their equivalents.

Claims

1. A method performed by a terminal in a wireless communication system, the method comprising: Receiving a radio resource control (RRC) message for configuring one or more beam failure detection (BFD) sets from a base station, wherein each of the one or more BFD sets includes at least one BFD reference signal (BFD-RS); In a case where the number of BFD-RSs of the corresponding BFD set is less than or equal to a threshold, identifying that the BFD-RSs of the corresponding BFD set are activated; and In a case where the number of BFD-RSs of the corresponding BFD set is greater than the threshold, it is identified that the BFD-RSs of the corresponding BFD set are deactivated.

2. The method according to claim 1, further comprising: In a case where the number of BFD-RSs of the corresponding BFD set is greater than the threshold, receiving from the base station a medium access control MAC control element CE for indicating an updated BFD-RS of the corresponding BFD set; as well as The updated BFD-RS of the corresponding BFD set indicated by the MAC CE is received from the base station.

3. The method according to claim 2, wherein: The MAC CE indicates one or two BFD-RSs for the corresponding BFD set.

4. The method according to claim 1, further comprising: In a case where the number of BFD-RSs of the corresponding BFD set is less than or equal to the threshold, receiving the BFD-RSs of the corresponding BFD set from the base station, and The threshold includes a maximum number of BFD-RSs that can be monitored by the terminal, and the threshold is 1 or 2.

5. A method performed by a base station in a wireless communication system, the method comprising: Sending a radio resource control (RRC) message for configuring one or more beam failure detection (BFD) sets to a terminal, wherein each of the one or more BFD sets includes at least one BFD reference signal (BFD-RS); When the number of BFD-RSs of the corresponding BFD set is less than or equal to a threshold, activating the BFD-RSs of the corresponding BFD set; and In a case where the number of BFD-RSs of the corresponding BFD set is greater than the threshold, the BFD-RSs of the corresponding BFD set are deactivated.

6. The method according to claim 5, further comprising: When the number of BFD-RSs of the corresponding BFD set is greater than the threshold, sending a medium access control MAC control element CE for indicating an updated BFD-RS of the corresponding BFD set to the terminal; as well as sending the updated BFD-RS of the corresponding BFD set indicated by the MAC CE to the terminal, The MAC CE indicates one or two BFD-RSs used for the corresponding BFD set.

7. The method according to claim 5, further comprising: When the number of BFD-RSs of the corresponding BFD set is less than or equal to the threshold, sending the BFD-RSs of the corresponding BFD set to the terminal, The threshold includes a maximum number of BFD-RSs that can be monitored, and the threshold is 1 or 2.

8. A terminal in a wireless communication system, the terminal comprising: Transceiver; as well as a controller coupled to the transceiver and configured to: receiving a radio resource control (RRC) message for configuring one or more beam failure detection (BFD) sets from a base station, wherein each of the one or more BFD sets includes at least one BFD reference signal (BFD-RS), In a case where the number of BFD-RSs of the corresponding BFD set is less than or equal to a threshold, identifying that the BFD-RSs of the corresponding BFD set are activated, and In a case where the number of BFD-RSs of the corresponding BFD set is greater than the threshold, it is identified that the BFD-RSs of the corresponding BFD set are deactivated.

9. The terminal according to claim 8, wherein: The controller is also configured to: In a case where the number of BFD-RSs of the corresponding BFD set is greater than the threshold, receiving a medium access control MAC control element CE for indicating an updated BFD-RS of the corresponding BFD set from the base station, and The updated BFD-RS of the corresponding BFD set indicated by the MAC CE is received from the base station.

10. The terminal according to claim 9, wherein: The MAC CE indicates one or two BFD-RSs for the corresponding BFD set.

11. The terminal according to claim 8, wherein: The controller is also configured to: In a case where the number of BFD-RSs of the corresponding BFD set is less than or equal to the threshold, receiving the BFD-RSs of the corresponding BFD set from the base station, The threshold includes a maximum number of BFD-RSs that can be monitored by the terminal, and the threshold is 1 or 2.

12. A base station in a wireless communication system, the base station comprising: Transceiver; as well as a controller coupled to the transceiver and configured to: Sending a radio resource control (RRC) message to a terminal for configuring one or more beam failure detection (BFD) sets, wherein each of the one or more BFD sets includes at least one BFD reference signal (BFD-RS), In a case where the number of BFD-RSs of the corresponding BFD set is less than or equal to a threshold, activating the BFD-RSs of the corresponding BFD set, and In a case where the number of BFD-RSs of the corresponding BFD set is greater than the threshold, the BFD-RSs of the corresponding BFD set are deactivated.

13. The base station according to claim 12, wherein: The controller is also configured to: In a case where the number of BFD-RSs of the corresponding BFD set is greater than the threshold, sending a medium access control MAC control element CE for indicating an updated BFD-RS of the corresponding BFD set to the terminal, and and sending the updated BFD-RS of the corresponding BFD set indicated by the MAC CE to the terminal.

14. The base station according to claim 13, wherein: The MAC CE indicates one or two BFD-RSs for the corresponding BFD set.

15. The base station according to claim 12, wherein: The controller is also configured to: When the number of BFD-RSs of the corresponding BFD set is less than or equal to the threshold, sending the BFD-RSs of the corresponding BFD set to the terminal, The threshold includes a maximum number of BFD-RSs that can be monitored, and the threshold is 1 or 2.

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