Method and device for inter-cell beam failure recovery in wireless communication system

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting higher data transmission rates. Specifically, the present invention relates to a method and device for simultaneously performing a beam failure recovery (BFR) process and a handover process on a terminal in consideration of link quality between the terminal and a plurality of cells including a serving cell.

Description

Method and device for inter-cell beam failure recovery in a wireless communication system

[0001] The present disclosure relates to a wireless communication system or a mobile communication system. Specifically, the present disclosure relates to a method and device for selecting a target cell in a beam failure situation and performing beam failure recovery for the target cell.

[0002] 5G mobile communication technology defines a wide frequency band to enable fast transmission speeds and new services, and can be implemented not only in the sub-6GHz frequency band such as 3.5 gigahertz (3.5GHz), but also in the ultra-high frequency band called millimeter wave (mmWave) such as 28GHz and 39GHz ('Above 6GHz'). In addition, for 6G mobile communication technology, which is called the system after 5G communication (Beyond 5G), implementation in the terahertz band (for example, the 3 terahertz (3THz) band at 95GHz) is being considered to achieve a transmission speed that is 50 times faster than 5G mobile communication technology and an ultra-low latency time that is reduced to one-tenth.

[0003] In the early stages of 5G mobile communication technology, the goal is to support services and satisfy performance requirements for enhanced Mobile Broadband (eMBB), Ultra-Reliable Low-Latency Communications (URLLC), and massive Machine-Type Communications (mMTC). These include beamforming and massive MIMO to mitigate path loss of radio waves in ultra-high frequency bands and increase the transmission distance of radio waves, support for various numerologies (such as operation of multiple subcarrier intervals) and dynamic operation of slot formats for efficient use of ultra-high frequency resources, initial access technology to support multi-beam transmission and wideband, definition and operation of BWP (Bidth Part), new channel coding methods such as LDPC (Low Density Parity Check) codes for large-capacity data transmission and Polar Code for reliable transmission of control information, and L2 pre-processing (L2). Standardization has been made for network slicing, which provides dedicated networks specialized for specific services, and pre-processing.

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

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

[0006] Once these 5G mobile communication systems are commercialized, an explosive increase in connected devices will be connected to the communication network, necessitating enhanced functionality and performance of 5G mobile communication systems and integrated operation of these connected devices. To this end, new research will be conducted on improving 5G performance and reducing complexity, supporting AI services, supporting metaverse services, and drone communications by utilizing eXtended Reality (XR), Artificial Intelligence (AI), and Machine Learning (ML) to efficiently support Augmented Reality (AR), Virtual Reality (VR), and Mixed Reality (MR).

[0007] In addition, the development of these 5G mobile communication systems includes new waveforms to ensure coverage in the terahertz band of 6G mobile communication technology, multi-antenna transmission technologies such as Full Dimensional MIMO (FD-MIMO), Array Antenna, and Large Scale Antenna, metamaterial-based lenses and antennas to improve the coverage of terahertz band signals, high-dimensional spatial multiplexing technology using Orbital Angular Momentum (OAM), Reconfigurable Intelligent Surface (RIS) technology, as well as full duplex technology to improve the frequency efficiency and system network of 6G mobile communication technology, satellite, AI (Artificial Intelligence) from the design stage and AI-based communication technology that realizes system optimization by internalizing end-to-end AI support functions, and ultra-high-performance communication and computing resources to provide services with complexity that exceeds the limits of terminal computing capabilities. It can serve as a basis for the development of next-generation distributed computing technologies that can be realized by utilizing them.

[0008] As described above and with the development of mobile communication systems, various services have become available, and methods for providing these services effectively are required.

[0009] The present disclosure can provide a method and device for simultaneously performing a BFR (beam failure recovery) process and a handover process for a terminal by considering link quality between a plurality of cells including a serving cell and the terminal.

[0010] In order to solve the above problems, the present disclosure provides a method of operating a terminal in a wireless communication system, the method including a step of receiving information on whether a mobility technique is applied from a source cell, a step of requesting a handover to a target cell, a step of establishing a link with the target cell, and a step of releasing the link with the source cell.

[0011] According to one embodiment of the present disclosure, superior mobility management performance compared to existing technologies can be supported through a simpler process. Furthermore, terminals can more quickly restore link quality degradation caused by beam failure.

[0012] FIG. 1 illustrates beam conversion when a beam failure (BF) occurs in a wireless communication system according to various embodiments of the present disclosure.

[0013] FIG. 2 illustrates the occurrence of BF due to a change in the communication environment in a wireless communication system according to various embodiments of the present disclosure.

[0014] FIG. 3 illustrates a novel cell-targeted beam failure recovery (BFR) technique in a wireless communication system according to various embodiments of the present disclosure.

[0015] FIG. 4 illustrates a signal flow in a method for a terminal to perform BFR for a non-serving cell in a wireless communication system according to various embodiments of the present disclosure.

[0016] FIG. 5 illustrates a signal flow in a method for a terminal to perform BFR for a non-serving cell in a wireless communication system according to various embodiments of the present disclosure.

[0017] FIG. 6 illustrates a method for setting an IC (inter cell)-beam RS (reference signal) in a wireless communication system according to various embodiments of the present disclosure.

[0018] FIG. 7 illustrates a method for allocating a physical random access channel (PRACH) resource used for a beam failure recovery request (BFRQ) and a resource used for non-serving cell beam sweeping in a wireless communication system according to various embodiments of the present disclosure.

[0019] FIG. 8 illustrates a method for allocating PRACH resources used for BFRQ and resources used for non-serving cell beam sweeping in a wireless communication system according to various embodiments of the present disclosure.

[0020] FIG. 9 illustrates a method for allocating PRACH resources used for BFRQ and resources used for non-serving cell beam sweeping in a wireless communication system according to various embodiments of the present disclosure.

[0021] FIG. 10 illustrates a method for transmitting IC-BSRS based on IC-BSRS (beam sweeping RS) resources and QCL (Quasi Co-Location) information in a wireless communication system according to various embodiments of the present disclosure.

[0022] FIG. 11 illustrates a method for transmitting IC-BSRS based on IC-BSRS resource and QCL information in a wireless communication system according to various embodiments of the present disclosure.

[0023] FIG. 12 illustrates a method for allocating BFRQ resources in a wireless communication system according to various embodiments of the present disclosure.

[0024] FIG. 13 illustrates a method for allocating BFRQ resources in a wireless communication system according to various embodiments of the present disclosure.

[0025] FIG. 14 is a diagram illustrating a configuration of a base station according to various embodiments of the present disclosure.

[0026] FIG. 15 is a diagram illustrating a configuration of a terminal according to various embodiments of the present disclosure.

[0027] The operating principles of the present disclosure are described in detail below with reference to the attached drawings. In the following description of the present disclosure, detailed descriptions of related known functions or configurations will be omitted if they are deemed to unnecessarily obscure the gist of the present disclosure. Furthermore, the terms described below are defined based on the functions of the present disclosure and may vary depending on the intent or custom of the user or operator. Therefore, their definitions should be based on the overall content of this specification.

[0028] In the following description of the present disclosure, detailed descriptions of related known functions or configurations will be omitted if they are deemed to unnecessarily obscure the gist of the present disclosure. Hereinafter, embodiments of the present disclosure will be described with reference to the attached drawings.

[0029] The terms used in the following description to identify connection nodes, terms referring to network entities, terms referring to messages, terms referring to interfaces between network entities, and terms referring to various identification information are provided as examples for convenience of explanation. Therefore, the present disclosure is not limited to the terms described below, and other terms referring to objects with equivalent technical meanings may be used.

[0030] Hereinafter, the base station is an entity that performs resource allocation of the terminal, and may be at least one of a gNode B, an eNode B, a Node B, a BS (Base Station), a wireless access unit, a base station controller, or a node on a network. The terminal may include a UE (User Equipment), an MS (Mobile Station), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing a communication function. In the present disclosure, downlink (DL) refers to a wireless transmission path of a signal transmitted from a base station to a terminal, and uplink (UL) refers to a wireless transmission path of a signal transmitted from a terminal to a base station. In addition, although the LTE or LTE-A system may be described below as an example, the embodiments of the present disclosure may also be applied to other communication systems having similar technical backgrounds or channel types. For example, the 5th generation mobile communication technology (5G, new radio, NR) developed after LTE-A may be included in a system to which the embodiments of the present disclosure may be applied, and 5G below may also be a concept that includes existing LTE, LTE-A, and other similar services. Furthermore, the present disclosure may be applied to other communication systems with some modifications, as determined by a person skilled in the art, without significantly departing from the scope of the present disclosure. It will be appreciated that each block of the processing flow diagrams and combinations of the flow diagrams can be executed by computer program instructions.

[0031] These computer program instructions may be installed in a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus, so that the instructions executed by the processor of the computer or other programmable data processing apparatus create means for performing the functions described in the flowchart block(s). These computer program instructions may also be stored in a computer-available or computer-readable memory that can be directed to a computer or other programmable data processing apparatus to implement functions in a particular manner, so that the instructions stored in the computer-available or computer-readable memory can produce an article of manufacture that includes instruction means for performing the functions described in the flowchart block(s). The computer program instructions may also be installed on a computer or other programmable data processing apparatus, so that a series of operational steps are performed on the computer or other programmable data processing apparatus to create a computer-implemented process, so that the instructions executing on the computer or other programmable data processing apparatus can provide steps for performing the functions described in the flowchart block(s).

[0032] Additionally, each block may represent a module, segment, or portion of code that contains one or more executable instructions for executing a specific logical function(s). It should also be noted that in some alternative implementation examples, the functions mentioned in the blocks may occur out of order. For example, two blocks shown in succession may in fact be executed substantially simultaneously, or the blocks may sometimes be executed in reverse order depending on the corresponding function. In this case, the term '~unit' used in the present embodiment means software or a hardware component such as an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit), and the '~unit' may perform certain roles. However, the '~unit' is not limited to software or hardware. The '~unit' may be configured to be on an addressable storage medium and may be configured to execute one or more processors. Thus, as an example, the '~ unit' includes components such as software components, object-oriented software components, class components, and task components, processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functionality provided within the components and '~ units' may be combined into a smaller number of components and '~ units' or further separated into additional components and '~ units'. In addition, the components and '~ units' may be implemented to reproduce one or more CPUs within a device or a secure multimedia card. Also, in an embodiment, the '~ unit' may include one or more processors.

[0033] For convenience of explanation, this disclosure uses terms and names defined in the 5GS and NR standards, which are standards defined by the 3rd Generation Partnership Project (3GPP) among the existing communication standards. However, this disclosure is not limited to the above terms and names and can be equally applied to wireless communication networks that follow other standards. For example, this disclosure can be applied to the 3GPP 5GS / NR (5th generation mobile communication standard).

[0034] To meet the growing demand for wireless data traffic following the commercialization of 4G (4th generation) communication systems, efforts are being made to develop improved 5G (5th generation) communication systems, or pre-5G communication systems. For this reason, 5G communication systems, or pre-5G communication systems, are also referred to as "Beyond 4G Network" communication systems or "Post-LTE" systems.

[0035] To achieve high data rates, 5G communication systems are being considered for implementation in ultra-high frequency (mmWave) bands (e.g., 60 GHz bands). To mitigate radio path loss and increase the transmission range of radio waves in ultra-high frequency bands, beamforming, massive MIMO, full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and large-scale antenna technologies are being discussed in 5G communication systems.

[0036] Additionally, to improve the network of the system, technologies such as evolved small cells, advanced small cells, cloud radio access networks (cloud RAN), ultra-dense networks, device-to-device communication (D2D), wireless backhaul, moving networks, cooperative communication, CoMP (Coordinated Multi-Points), and interference cancellation are being developed in 5G communication systems.

[0037] In addition, advanced coding modulation (ACM) methods such as FQAM (Hybrid FSK and QAM Modulation) and SWSC (Sliding Window Superposition Coding), as well as advanced access technologies such as FBMC (Filter Bank Multi Carrier), NOMA (non-orthogonal multiple access), and SCMA (sparse code multiple access) are being developed in 5G systems.

[0038] 5G systems are considering supporting a wider range of services compared to existing 4G systems. For example, representative services include enhanced mobile broadband (eMBB), ultra-reliable and low latency communication (URLLC), massive machine type communication (mMTC), and evolved multimedia broadcast / multicast service (eMBMS). A system that provides URLLC services may be referred to as a URLLC system, and a system that provides eMBB services may be referred to as an eMBB system. Furthermore, the terms "service" and "system" may be used interchangeably.

[0039] Among these, URLLC service is a new service being considered for 5G systems, unlike existing 4G systems. Compared to other services, it requires ultra-high reliability (e.g., a packet error rate of approximately 10^-5) and low latency (e.g., approximately 0.5 msec). To satisfy these stringent requirements, URLLC service may require a shorter transmission time interval (TTI) than eMBB service, and various operation methods utilizing this are being considered.

[0040] Meanwhile, the Internet is evolving from a human-centric network where humans create and consume information to an Internet of Things (IoT) network where information is exchanged and processed between distributed components such as objects. The Internet of Everything (IoE) technology, which combines IoT technology with big data processing technology through connection to cloud servers, is also emerging. To implement IoT, technological elements such as sensing technology, wireless communication and network infrastructure, service interface technology, and security technology are required. Recently, technologies such as sensor networks for connecting objects, machine-to-machine (M2M), and machine-type communication (MTC) are being studied.

[0041] In an IoT environment, intelligent IT (Internet Technology) services can be provided that collect and analyze data generated from connected objects, creating new value in human life. IoT can be applied to areas such as smart homes, smart buildings, smart cities, smart or connected cars, smart grids, healthcare, smart appliances, and advanced medical services through the convergence and integration of existing IT (information technology) technologies with various industries.

[0042] Accordingly, various attempts are being made to apply 5G communication systems to IoT networks. For example, technologies such as sensor networks, machine-to-machine (M2M), and machine-type communication (MTC) are being implemented using 5G communication techniques such as beamforming, MIMO, and array antennas. The application of cloud radio access networks (cloud RAN), a big data processing technology described above, can also be considered an example of the convergence of 5G and IoT technologies.

[0043] Inter-cell handover (or HO) and support for terminal mobility are core technologies in mobile communications. Furthermore, maintaining and managing beams to maintain and improve links is also an essential technology in current cellular systems, where base stations perform transmission beamforming. When a Beam Failure (BF) occurs, the terminal requests the serving cell to initiate a beam failure recovery (BFR) process via a Beam Failure Recovery Request (BFRQ). This BFR process then switches to a new beam, restoring the degraded link quality. If a terminal experiences a BF due to the loss of a Line of Sight (LoS) path, this can result in a severe link quality degradation that cannot be overcome by BFR between the serving cell and the terminal. This situation should be understood as a situation where link quality restoration through BF is impossible. The present disclosure proposes a technique for restoring link quality more quickly in such situations, where the terminal requests BFR and handover to a new cell that can guarantee superior link quality, rather than triggering a BFR to the serving cell.

[0044] Meanwhile, to secure wideband, cellular systems are implementing communication systems in higher bands as their generations evolve. As bandwidth increases, beamforming technology has been adopted as a 5G standard to overcome increasing path loss at base station transmitters and receivers. In the mmWave band, known as Frequency Range 2 (FR2), where communications occur at extremely high bands, the use of transmit and receive beams with extremely narrow beam-widths is required. As the generation evolves to 6G, communication systems are expected to be implemented in bands above 6 GHz. Therefore, compared to the current 3 GHz band used by 5G systems, narrower beams are expected to be used to secure greater beamforming gain.

[0045] When beamforming techniques are applied, beam management techniques are applied to stably maintain the beam or beam pair between the network and terminals. Beam management techniques can be divided into an initial beam acquisition process, a beam maintenance process, and a beam failure recovery process, depending on the operational purpose of each process. The initial beam acquisition process can perform the initial beam setup task for communication between the terminal and the base station. Thereafter, the beam maintenance process can continuously detect an appropriate beam and, if the optimal beam changes according to changes in the communication environment, support continuation of communication through the new beam. If the beam maintenance process fails to continuously detect an excellent beam and update the beam, it can be defined as a Beam Failure (BF). If a BF occurs, a BFR process can be performed to search for a new beam and change to the new beam.

[0046] There are two main causes of BF. When a terminal moves, the angular direction between the terminal and the base station responsible for the serving cell may change. Due to the directivity-based nature of beamforming, this change in angular direction can significantly reduce beamforming gain from the existing beam. Therefore, beam conversion to a new beam that matches the changed angular direction is necessary.

[0047] FIG. 1 illustrates beam conversion when BF occurs in a wireless communication system according to various embodiments of the present disclosure.

[0048] Referring to FIG. 1, a mobile terminal can perform communication via beam #2. For example, beam #2 can be applied to communication between a base station and a terminal, and beam #1 and beam #3 can also be defined as active beams or active TCI states. In addition, when a change in the communication environment occurs, communication using beam #1 or beam #3, which are similar to beam #2 but support beamforming in a different direction, can be supported. If a terminal moves faster than expected and none of beams #1 to #3 can provide appropriate beamforming gain or link quality, a BF is declared and beam #4 can be set as a new beam through the BFR process. Thereafter, multiple active beams or active TCI states can be set through beam maintenance work, and communication can proceed using the set active beams or TCI states.

[0049] Another cause of BF may be a change in the communication environment. For example, if the path and / or line of sight between the base station and the terminal is interrupted by an object, the base station may use a new beam to communicate with the terminal.

[0050] FIG. 2 illustrates the occurrence of BF due to a change in the communication environment in a wireless communication system according to various embodiments of the present disclosure.

[0051] Referring to Figure 2, if the communication environment changes to a situation where a beam that guarantees link quality similar to the existing beam no longer exists, such as when the LoS between the base station and the terminal is disconnected, the terminal may still experience low link quality even after a BFR. The network's solution to this situation may be to handover to a new cell after the BFR. Therefore, after the BF occurs, the terminal may experience a prolonged degradation in link quality until the BFR is performed and the handover process is completed.

[0052] As a solution to the above-described link quality degradation, the present disclosure proposes a technique for performing BFR on a new cell rather than a serving cell based on the judgment of the terminal when BF occurs.

[0053] FIG. 3 illustrates a novel cell-targeted BFR technique in a wireless communication system according to various embodiments of the present disclosure.

[0054] Referring to FIG. 3, when a BF occurs, the terminal may select and perform either the existing serving cell-targeted BFR technique or the new cell-targeted BFR technique proposed by the present disclosure. Alternatively, the terminal may perform one of the two techniques according to the configuration of the base station and / or the serving cell. When performing the existing serving cell-targeted BFR technique, the terminal may receive a first cut-off value for the number of times the BFR process is performed from the base station and / or the serving cell, or may determine the first cut-off value on its own. If the BFR process fails by a factor equal to or greater than the first cut-off value, the terminal may perform the new cell-targeted BFR process proposed by the present disclosure, or transmit a handover request to the serving cell. The terminal may determine which operation to perform between the new BFR process and the handover request. Alternatively, the terminal may determine which operation to perform between the new BFR process and the handover request, depending on the configuration of the base station and / or the serving cell.

[0055] When a BFR process targeting a new cell is performed, the terminal can select a target cell for the BFR. Alternatively, the target cell may be determined based on network and / or serving cell settings. Alternatively, multiple candidate cells may be configured based on network and / or serving cell settings, and the terminal may select one or some of the candidate cells as target cells to perform the BFR operation. For example, the BFR process targeting a new cell may be performed simultaneously targeting one or more target cells.

[0056] When performing BFR for the new cell, the terminal may receive a second cut-off value from the base station and / or the serving cell, or may determine the second cut-off value on its own. If the terminal fails BFR for the new cell or target cell by a value greater than or equal to the second cut-off value, the terminal may stop the BFR operation and request a handover process. Alternatively, if the terminal fails BFR for the target cell by a value greater than or equal to the second cut-off value, the terminal may set a new target cell and perform BFR for the target cell. Performing BFR for the new target cell may be performed by setting a third cut-off value or by a value defined by the terminal. If the terminal has a third cut-off value and fails BFR by a value greater than or equal to the second cut-off value, the terminal may change the target cell as described above and perform the BFR process. If the terminal subsequently fails BFR by a value greater than or equal to the third cut-off value, the terminal may switch to the handover process. Alternatively, the terminal may request the base station to switch to the handover process.

[0057] Below is a more detailed explanation of each step.

[0058] The following methods may be applied to the details of the operation of the terminal shown in Fig. 3 to select a BFR process. The network and / or the serving cell may determine the BFR process to be performed by the terminal and notify the terminal of the same. In case 1 and case 1-1, the network may be configured to perform a serving cell-targeted BFR process for a specific terminal. In case 2, the network may be configured to perform a non-serving cell-targeted BFR process for a specific terminal. For example, the network may be configured to give priority to performing a serving cell-targeted BFR process for a specific terminal. Alternatively, the network may be configured to perform only a serving cell-targeted BFR for a specific terminal. Alternatively, the network may specify a BFR process selection method for a specific terminal. For example, the terminal may be configured to measure link quality for candidate beams (e.g., all beams that the terminal can request from the base station as a new beam), select a new beam among the candidate beams, and request BFR based on the new beam. At this time, if the new beam corresponds to a serving cell beam, the existing serving cell-targeted BFR process can be performed. If the new beam corresponds to a non-serving cell beam, the new cell-targeted BFR process can be performed (Case 2). As another example, a cell-specific BFR priority can be defined. At this time, the terminal can consider the cell-specific priority when comparing the link qualities that the candidate beams can provide.For example, if a threshold value of +3dB is defined as a priority for a serving cell, the terminal can request the base station to perform a new cell-targeted BFR process targeting the beam and the cell only if there is a beam among the non-serving cell beams that guarantees link quality that is at least 3dB better than the best beam of the serving cell. As another method of priority selection, the terminal can give priority to the BFR process targeting the cell with the highest priority. If the BFR targeting the highest priority cell fails, the terminal can perform the BFR process targeting the cell with the next lowest priority. If multiple cells have the same priority, the terminal can measure the candidate beam link quality for the cells and perform the BFR process or request the BFR process to the base station for the cell and beam that provides the best link quality.

[0059] The following may be applied to the detailed operations for case 1 and case 1-1 shown in Fig. 3. When performing a BFR process for a serving cell, the terminal may receive a setting for the maximum number of attempts from the base station in the form of a cut-off value, or may set (determine) the value for the maximum number of attempts on its own. The cut-off value may be referred to as a first cut-off value. When performing a BFR process for a serving cell, if the BFR process fails by a value greater than the cut-off value, the terminal may recognize that the BFR for the serving cell is impossible and may switch to a BFR for a non-serving cell (case 1) or to an HO process (case 1-1). The terminal may receive the minimum beam / link quality from the base station or may set it on its own. For a new beam selected during the BFR process, the terminal may perform link quality measurement based on DL RS (reference signal) measurement. In addition, the terminal may recognize that the BFR has failed if the link quality of the new beam is lower than the set minimum beam / link quality.

[0060] As another implementation, the terminal can continuously measure the link quality provided by the new beam during the BFR process. At this time, if the link quality is lower than the configured minimum threshold value, the terminal can stop the BFR process regardless of the number of BFR failures and switch to case 1 or case 1-1. Alternatively, the terminal can receive the first cut-off value, the first link quality threshold, and the second link quality threshold from the base station, and if the link quality in the event of a BFR failure is lower than the first link quality threshold, the process can be switched to a non-serving cell target BFR (case 1), and if it is lower than the second link quality threshold, the process can be switched to a handover (case 1-1). The above example is an example of a case where the BFR process is changed by a terminal decision, but the BFR process switching may also be determined by a base station decision. For example, a serving cell that has received a BFRQ can decide to handover to the terminal that transmitted the BFRQ if the number of BFRQ receptions is greater than an appropriate number and transmit a handover command or cell switch command to the terminal. As described above, if the terminal transmits a BFRQ and receives a handover command or cell switch command while BFR is being performed, the terminal can stop the BFR process that was being performed and perform the handover process.

[0061] The non-target cell BFR process proposed by the present disclosure can be implemented in two ways: a case where a terminal transmits a BFRQ to a serving cell, and a case where a terminal selects one or more BFR target cells and directly transmits a BFRQ to the target cells.

[0062] FIG. 4 illustrates a signal flow in a method for a terminal to perform BFR for a non-serving cell in a wireless communication system according to various embodiments of the present disclosure.

[0063] Referring to FIG. 4, an example is described for a case where a terminal transmits a BFRQ to a serving cell when performing BFR for a non-serving cell. To support DL measurement for a terminal for a non-serving cell, the serving cell can set a candidate cell as the target of DL measurement for the terminal. Furthermore, in an embodiment of the present disclosure, the serving cell may refer to the same cell as the source cell, and the candidate cell may refer to the same cell as the target cell.

[0064] In step 405, the candidate cell or target cell may transmit configuration information or measurement information required for DL ​​measurement of the candidate cell to the terminal via the serving cell. The candidate cell configuration may include configuration information for the RS on which the terminal will perform DL measurement for the established candidate cell, as well as reporting configuration information for reporting the measurement results.

[0065] In step 410, the terminal may perform an early RACH operation to secure timing advance (TA) before handover, if necessary. Additionally, when the terminal performs a physical random access channel (PRACH) transmission targeting a candidate cell, it may include information about the PRACH transmission resource.

[0066] In step 415, the candidate cell can obtain the UL TA value (e.g., UL timing information) of the terminal through the early RACH (random access channel) and transmit it to the serving cell.

[0067] In step 420, the serving cell can transmit beam RS configuration to the terminal. For example, when the terminal requests a non-serving cell target BFR from the base station, the serving cell can transmit information about a beam that the terminal can select as a new beam or candidate new beam in the form of a beam RS configuration to the terminal. The beam information can be transmitted to the terminal in the form of a DL RS resource configuration, and the terminal can recognize that it is performing a beam candidate new beam or new beam selection task through RS resources or RS measurement. For example, the new beam or candidate new beam can be selected by selecting one or more RSs among the above RSs and transmitting an index of the RS to the base station.

[0068] In step 425, if a separate measurement RS is required for the terminal to search for a new beam during the BFR process, the candidate cell can transmit information about the measurement RS to the terminal through the serving cell in the form of a non-serving cell beam measurement RS or an inter-cell beam RS (hereinafter referred to as IC-beam RS).

[0069] In step 430, the candidate cell can define information about radio resources used for UL signaling and DL signaling occurring during BFR operation and transmit this to the terminal through the serving cell.

[0070] In step 435, when a BF occurs, the terminal can perform a search operation for a beam suitable for use as a new beam and then transmit a BFRQ to the serving cell. The beam selected by the terminal through the search operation may be referred to as a candidate new beam hereinafter. The terminal can select one or more candidate beam(s) through the above operation.

[0071] At step 440, the serving cell that received the BFRQ can transmit one or more candidate beam(s) to the target cell.

[0072] In step 445, the target cell can perform beam sweeping, and the terminal can select a new beam through beam sweeping. The selected beam may be referred to as a new beam hereinafter. The final selected new beam may be the candidate new beam selected by the terminal in the previous step or one of the candidate new beams. If the terminal selects a candidate new beam and reports it to the serving cell before BFRQ transmission, the base station can determine that the new beam selection has already been completed. In this case, the beam sweeping operation may be omitted.

[0073] In step 450, the terminal can transmit information about the new beam (e.g., the beam index for the new beam) to the target cell that transmitted the new beam. After receiving the information about the new beam, the target cell can notify the terminal that reception was successful.

[0074] In step 455, the target cell may notify the UE's previous serving cell that a handover has been requested and is ready to be performed. The serving cell may transmit an acknowledgement message to the target cell regarding the notification, thereby completing the BFR operation.

[0075] Another method for triggering a BFR process for a non-serving cell may be a method in which a terminal selects a target cell and directly transmits a BFRQ to the target cell. The above-described method is described below in FIG. 5.

[0076] FIG. 5 illustrates a signal flow in a method for a terminal to perform BFR for a non-serving cell in a wireless communication system according to various embodiments of the present disclosure. Each step of FIG. 5 may include operations that overlap with each step of FIG. 4 described above, and any overlapping descriptions may be omitted below.

[0077] Referring to FIG. 5, in order to support DL measurement for a non-serving cell of a terminal, a serving cell can set a candidate cell that is the target of DL measurement to the terminal.

[0078] In step 505, the candidate cell can transmit configuration information or measurement information required for DL ​​measurement targeting the candidate cell to the terminal through the serving cell.

[0079] At step 510, the serving cell can transmit beam RS configuration to the terminal.

[0080] In step 515, if a separate measurement RS is required for the terminal to search for a new beam during the BFR process, the candidate cell can transmit information about the measurement RS to the terminal through the serving cell in the form of a non-serving cell beam measurement RS or an inter-cell beam RS (hereinafter referred to as IC-beam RS).

[0081] In step 520, the candidate cell can define information about radio resources used for UL signaling and DL signaling that occur during BFR operation, and can transmit information about radio resources used for the defined UL signaling and DL signaling to the terminal through the serving cell.

[0082] In step 525, when BF occurs, the terminal selects one or more target cells based on the candidate new beam or new beam searched after searching for a candidate new beam or new beam, and can transmit a BFRQ to the target cell.

[0083] At step 530, the target cell that received the BFRQ can transmit to the terminal that it has successfully received the BFRQ in the form of a random access response (RAR).

[0084] At step 535, the target cell notifies the terminal's existing serving cell that it has successfully received BFRQ, thereby terminating the BFR and handover process.

[0085] FIG. 6 illustrates a method for setting up an IC-beam RS in a wireless communication system according to various embodiments of the present disclosure.

[0086] Referring to Fig. 6, each IC-beam RS resource may be referred to as IC-BRS #N. The number of IC-beam RSs that the base station can configure for each terminal or the IC-beam RS resource configuration size may be determined by the terminal's capability and the total number of beam measurement RSs configured in the terminal. For example, the number of IC-beam RSs configured for a terminal may be less than or equal to the number defined by the terminal capability. In the example of Fig. 6, the base station may consider a case in which six IC-beam RSs are allocated to the terminal. Considering a case in which two candidate cells are configured, three IB-beam RSs are selected for each candidate cell, so that a total of six beam measurement reference signals can be transmitted to the terminal through the indices of IC-BRS #0 to #5. Thereafter, when the terminal transmits one index of IC-BRS #0 to #5 to the base station through BFRQ, the base station can recognize that the terminal has requested the beam of the DL RS connected to the corresponding IC-BRS as a new beam or candidate new beam. For example, in the example of FIG. 6, if the terminal requests the base station for IC-BRS#1 as a new beam, the base station can recognize that the SSB#1 of candidate cell #0 has been requested as a new beam. In the example of FIG. 6, it is assumed that the SSB of each candidate cell is configured as an IC-beam RS resource, but other types of RS, such as CSI-RS, may also be configured as IC-beam RS resources. As another example, the base station may omit the IC-beam RS configuration task. Alternatively, the base station may not configure the IC-beam RS for some of the configured candidate cells.

[0087] FIGS. 7 to 9 illustrate a method of allocating PRACH resources used for BFRQ and resources used for non-serving cell beam sweeping in a wireless communication system according to various embodiments of the present disclosure.

[0088] Referring to FIGS. 7 to 9, a base station can configure PRACH resources to be used when a terminal requests BFR targeting a non-serving cell. When configuring resources, the base station can configure information regarding which beam RS each PRACH resource is connected to. If the number of non-serving cell beam RSs is greater than the number of configured PRACH resources, the base station can connect two or more non-serving cell beam RSs to each PRACH resource. The example of FIG. 7 illustrates a case where the base station configures three PRACH resources for BFRQ for non-serving cells, and two IC-beam RSs are connected to each PRACH resource. The PRACH resources described above may be referred to as IC-BFRQ. In the example of FIG. 7, the same number of IC-beam RSs is connected to each PRACH resource, but as in the example of FIG. 8, a different number of IC-beam RSs may be connected to each PRACH resource. Alternatively, as in the example of Fig. 9, PRACH resources may be connected to each candidate cell, or multiple candidate cells may be connected to a single PRACH resource. Alternatively, one or more PRACH resources may be configured as BFRQ resources for non-serving cells, regardless of the candidate cell and IC-beam RS configuration. Figs. 7 to 9 may be examples for cases where IC-BRS is defined. If IC-BRS is not separately defined, the base station may directly configure the relationship between IC-BFRQ and the DL RS resources of each candidate cell.

[0089] After BFRQ resources are configured, RS resources to be used for beam sweeping can be configured. The number of RS resources to be used for beam sweeping can be defined according to the relevant capabilities of the terminal. In addition, the number of RS resources allowed may vary depending on the beam sweeping method. For example, when RS resources are configured for base station tx beam sweeping and when the RS resources are configured for terminal rx beam sweeping, different maximum numbers of RS resources can be defined according to UE capabilities. QCL (Quasi Co-Location) information or beam information for each RS resource can be defined in a later stage. RSs configured for target cell or non-serving cell beam sweeping may be referred to as IC-BSRS (beam sweeping RS) hereinafter.

[0090] When a terminal requests a BFR targeting a non-serving cell through a BFRQ transmission to a serving cell, the terminal can perform a PRACH transmission using the PRACH resource defined in the previous step. The serving cell can recognize that the terminal has requested a BFR targeting a non-serving cell through PRACH reception. In addition, the serving cell can identify a new beam, candidate new beam, or target cell selected by the terminal based on the connection between the defined PRACH resource and the IC-BM resource, or QCL information. For example, when an IC-BRS resource and an IC-BFRQ resource are connected according to the examples of FIGS. 6 and 7, or when a QCL relationship is established, when the terminal transmits a BFRQ using IC-BFRQ #0, the base station can identify that the terminal has selected IC-BRS #0 and IC-BRS #1 as candidate new beams according to the settings of FIG. 7. In addition, the base station can identify that the IC-BRS #0 and IC-BRS #1 indicate SSB #0 and SSB #1 of candidate cell #0, respectively, according to the settings of FIG. 6. For example, the base station can recognize that the terminal has selected candidate cell #0 as a target cell and has selected SSB #0 and SSB #1 of candidate cell #0 as a candidate new beam or a QCL source of the candidate new beam. When the terminal transmits a BFRQ through IC-BFRQ #0 according to the settings of FIG. 6 and FIG. 8, the transmitted BFRQ is connected to IC-BRS #0, and the fact that the BFRQ is connected to IC-BRS #0 can indicate SSB #0 of candidate cell #0.Therefore, the base station can recognize that the terminal has selected candidate cell #0 as the target cell and SSB #0 as the new beam. At this time, the target / non-serving cell beam sweeping operation may be omitted.

[0091] As a next step operation, the target cell can define QCL information for each configured IC-BSRS resource. The QCL information can be defined by the IC-BFRQ radio resource transmitted by the terminal in the previous step. For example, if the configuration according to the examples of FIGS. 6 and 7 is performed and the terminal transmits BFRQ through IC-BFRQ #0, the base station can use SSB #0 and SSB #1 of candidate cell #0 as the QCL source of each IC-BFRQ resource. At this time, the base station can allocate the RS resource indicated by each IC-BRS index in descending order of the IC-BRS index indicated by IC-BFRQ as the QCL source of each IC-BSRS. In the above example, IC-BFRQ #0 is received and IC-BRS #0 and IC-BRS #1 are indicated, which can correspond to SSB #0 and SSB #1 of candidate cell #0, respectively. Therefore, SSB #0 of candidate cell #0 can be the QCL source of IC-BSRS resource #0, and SSB #1 of candidate cell #0 can be the QCL source of IC-BSRS resource #1.

[0092] The above mapping rule can be applied differently depending on the purpose of use of each IC-BSRS resource. For example, if IC-BSRS resources #0 and #2 are set for base station beam sweeping purposes, and IC-BSRS resources #1 and #3 are set for terminal beam sweeping purposes or base station beam repetition purposes, when applying the above example, SSB #0 and SSB #1 of candidate cell #0 can be applied as QCL sources to IC-BSRS resources #0 and #2, respectively. Afterwards, SSB #0 of candidate cell #0, which is the QCL source of IC-BSRS resource #0, can be applied as the QCL source of IC-BSRS resource #1, and in the same way, SSB #1 of candidate cell #0 can be applied as the QCL source of IC-BSRS resource #3. For example, QCL sources are sequentially mapped to IC-BSRS resources set for base station beam sweeping purposes, and then the QCL sources set for each IC-BSRS resource can be applied to IC-BSRS resources for terminal beam sweeping or IC-BSRS resources for beam repetition linked to the IC-BSRS resource. IC-BSRS resources for base station beam sweeping and IC-BSRS resources for terminal beam sweeping or beam repetition can be distinguished by specifying their purposes in the resource configuration phase, and the connection relationship between resources with different purposes can also be defined through configuration.Alternatively, if an IC-BSRS resource specified as IC-BSRS resource index #0, #3, #5, etc. is defined for base station beam sweeping, a value in between may be the resource index. In addition, the QCL source of the IC-BSRS resource with the previous index may be applied to the IC-BSRS resource defined for terminal beam sweeping or beam repetition purposes. For example, the same QCL source may be applied to IC-BSRS resources #0 to #2. The same QCL source may be applied to IC-BSRS resources #3 to #4. In addition, the same QCL source as IC-BSRS resource #5 may be applied to the following QCL sources. In another QCL source application method, if multiple IC-BSRS resource sets are defined, the QCL source may be applied sequentially from a smaller value according to the resource set index value. The method of applying the QCL source in the order of the resource set index may be the same or similar in spirit to the method of applying the QCL source in the order of the resource index described above. Additionally, the same QCL source can be applied to each IC-BSRS resource belonging to each IC-BSRS resource set. When multiple IC-BSRS resource sets are configured, the number of configurable IC-BSRS resource sets can be defined according to the relevant capabilities of the terminal.

[0093] As a next step action, the previously selected target cell can perform IC-BSRS transmission based on the previously set IC-BSRS resource and QCL information.

[0094] FIG. 10 illustrates a method for transmitting IC-BSRS based on IC-BSRS resource and QCL information in a wireless communication system according to various embodiments of the present disclosure.

[0095] Referring to FIG. 10, a time offset between a BFRQ transmission of a terminal and an IC-BSRS reception of the terminal may be defined for transmitting an IC-BSRS based on IC-BSRS resource and QCL information. In addition, among the wireless resources defined by the IC-BSRS resource settings, the IC-BSRS transmission may be performed through a wireless resource that can support the fastest IC-BSRS transmission among the wireless resources that guarantee a time difference greater than or equal to the time offset. If a wireless resource that satisfies the above conditions is used for SSB transmission of a target cell, the wireless resource may not be used for IC-BSRS transmission. In addition, excluding the wireless resources that cannot be used, a wireless resource that guarantees a time difference greater than or equal to the time offset and can support the fastest IC-BSRS transmission may be used for IC-BSRS transmission.

[0096] FIG. 11 illustrates a method for transmitting IC-BSRS based on IC-BSRS resource and QCL information in a wireless communication system according to various embodiments of the present disclosure.

[0097] Referring to FIG. 11, a terminal may be instructed or configured to receive an RAR after transmitting a BFRQ. Upon receiving an RAR, the terminal may recognize that the BFRQ transmission is successful. A time offset T1 may be defined between the BFRQ transmission of the terminal and the RAR reception of the terminal. The terminal may perform IC-BSRS reception after receiving the RAR, and a minimum time difference time offset T2 may be defined between the RAR reception and the IC-BSRS reception. Alternatively, without defining a separate time offset, transmission and reception of the IC-BSRS may be performed through a radio resource that can transmit the IC-BSRS most quickly after receiving the RAR. Alternatively, the base station may transmit information on the IC-BSRS transmission and reception timing to the terminal via the RAR. The time offset T1 may be set by a separate configuration or defined by a standard. Alternatively, it may be determined according to the RAR window definition without a separate definition.

[0098] The details of the method in which the terminal selects a target cell and directly transmits BFRQ to the target cell as described above are as follows. As details of BFR resource allocation, the base station can allocate PRACH radio resources used for BFRQ for each target cell or each candidate new beam of each target cell. When a PRACH is received through the corresponding PRACH resource, the base station can identify that the PRACH transmission was used for BFRQ purposes and can then perform RAR transmission. Alternatively, the base station can allocate PRACH resources used for BFRQ purposes and PRACH resources used for LTM purposes without distinction. In this case, the base station can provide separate information to the terminal allocated the PRACH resource in the above manner as to which technique between BFRQ and LTM can be requested for each target cell. For example, if Cell A allocates PRACH radio resources to terminal #0 in the above manner and Cell A notifies terminal #0 that it supports only LTM, the terminal can use the PRACH resource only for LTM purposes (e.g., early RACH purposes). Conversely, if Cell A allocates PRACH resources to terminal #0 in the above manner and notifies terminal #0 that it supports non-serving cell BFR, the terminal can use the PRACH resource for BFRQ purposes.

[0099] FIG. 12 and FIG. 13 illustrate a method for allocating BFRQ resources in a wireless communication system according to various embodiments of the present disclosure.

[0100] Referring to Fig. 12, the base station of each cell can allocate BFRQ resources to terminals of neighboring cells that can set the cell as a candidate / target cell so that they can use different radio resources. For example, when allocating BFRQ resources to terminals of adjacent cell B, cell A can allocate radio resources corresponding to BFRQ indices #0 and #1 for SSB #0 and SSB #1 defined by IC-beam RS. For the same SSB, cell A can allocate BFRQ resources corresponding to indices #2 and #3, respectively, to terminals connected to cell C. Cell A can repeat the same operation for terminals connected to other cells. Through the above configuration, each cell can obtain information on which cell the terminal serving the cell transmitted the BFRQ, in addition to information on which beam was selected as the new beam when a non-serving terminal makes a BFRQ request. In addition, in order to reduce the amount of radio resources allocated to BFRQ, each cell can allocate a BFRQ per cell as in Fig. 13, or allocate one BFRQ resource to multiple beams as in the example of Fig. 7 described above. In this case, the terminal can select candidate new beams rather than new beams and report the selected candidate new beam (e.g., information about the selected candidate new beam) through BFRQ.

[0101] As a next step operation, the target cell that received the BFRQ can notify the terminal that the BFRQ was successfully received through RAR transmission. If a new beam was selected through BFRQ in the previous BFRQ step, the RAR can be transmitted through a beam corresponding to the new beam. For example, the target cell can apply the same RS as the BFRQ as a QCL source. On the other hand, if multiple candidate new beams are selected through the BFRQ, the QCL source applied to the RAR transmission can be determined in the following manner. If multiple candidate new beams are reported, the target cell can apply the QCL of the DL RS resource indicated by the smallest resource index among the candidate new beams to the RAR. For example, if the candidate new beam uses SSB #0 and SSB #1 of cell A as QCL sources, the RAR can be transmitted using SSB #0 as a QCL source. Or, in a manner similar to FIGS. 6 and 7, if SSB #1 of cell A is set to IC-BRS resource #0 and SSB #0 is set to IC-CRS #1, and an association or QCL sharing relationship between the IC-BRS resource and PRACH resource is set when allocating BFRQ resources, if the candidate new beam indicates IC-BRS resource #0 and IC-BRS resource #1, the target cell can select the beam of SSB #1 set to IC-BRS resource #0, which has a lower resource index, as the RAR transmission beam.In another RAR transmission method, when multiple candidate new beams are reported, the target cell can perform RAR transmission through multiple DL transmissions applying QCLs corresponding to each beam. For example, the target cell can perform RAR transmission in the form of RAR repetition transmission or beam sweeping.

[0102] After receiving the RAR, the terminal can notify the target cell that the BFR has been successful, and the target cell can then notify the terminal's existing serving cell that the BFR and handover have been completed. The BFR success notification can be performed via PUSCH or PUCCH radio resources. In addition, if multiple candidate new beams are reported, the terminal can report information about the finally selected new beam to the target cell through the BFR success notification. The reporting of information about the finally selected new beam can be performed by reporting a resource index. If one QCL source was applied to the RAR in the previous operation, the terminal can transmit a BFR notification message by applying the same QCL source. If multiple QCL sources were applied to the RAR and the RAR was transmitted in the form of beam sweeping, the terminal can transmit a BFR success message by applying one QCL source selected as a new beam among the multiple QCL sources.

[0103] In the case 3 and case 4 operations of the above-described Fig. 3, if the BFR targeting the target cell selected by the terminal fails a certain number of times or more, the terminal can exclude the target cell from the BFR target. For example, all DL RSs of the target cell can be excluded from the new beam selection target. The exclusion operation can be implemented by setting the fourth cut-off value. In addition, if the terminal fails the BFR targeting a non-serving cell a number of times or more than the fifth cut-off value, or fails the BFR targeting a target cell a number or more than the sixth cut-off value, the terminal can determine that link loss or link failure has occurred, and can start the initial access or handover process.

[0104] In the wireless communication system of the present disclosure as described above, the terminal may include a step of receiving permission for application of a mobility technique presented from a source cell, a step of receiving information on whether application of the mobility technique is permitted, a step of determining handover to a target cell and requesting handover to the target cell, a step of establishing a link between the terminal and the target cell when the target cell reviews and approves the request of the terminal, and a step of releasing the link between the terminal and the source cell.

[0105] FIG. 14 is a drawing for explaining the structure of a base station according to various embodiments of the present disclosure.

[0106] As illustrated in FIG. 14, the terminal of the present disclosure may include a processor (1420), a transceiver (1400), and a memory (1410). However, the components of the terminal are not limited to the examples described above. For example, the terminal may include more or fewer components than the components described above. Furthermore, the processor (1420), the transceiver (1400), and the memory (1410) may be implemented in the form of a single chip.

[0107] According to one embodiment of the present disclosure, the processor (1420) may control a series of processes by which the terminal may operate according to the embodiments of the present disclosure described above. For example, the processor (1420) may control components of the terminal to perform the antenna array adjustment method according to the embodiments described above. The processor (1420) may control components of the terminal to perform the embodiments of the present disclosure described above by executing a program stored in the memory (1410). In addition, the processor (1420) may be an Application Processor (AP), a Communication Processor (CP), a circuit, an application-specific circuit, or at least one processor.

[0108] According to one embodiment of the present disclosure, a transceiver (1400) can transmit and receive signals with a network entity, another base station, or a terminal. The signals transmitted and received with the network entity, another base station, or a terminal may include control information and data. The transceiver (1400) may be configured with an RF transmitter that up-converts and amplifies the frequency of a transmitted signal, and an RF receiver that low-noise amplifies and frequency-downconverts a received signal. However, the transceiver (1400) is only one embodiment, and the components of the transceiver (1400) are not limited to the RF transmitter and RF receiver. In addition, the transceiver (1400) may receive a signal through a wireless channel, output it to the processor (1420), and transmit the signal output from the processor (1420) through the wireless channel.

[0109] According to one embodiment of the present disclosure, the memory (1410) can store programs and data necessary for the operation of the terminal. In addition, the memory (1410) can store control information or data included in signals transmitted and received by the terminal. The memory (1410) can be configured as a storage medium or a combination of storage media, such as a ROM, a RAM, a hard disk, a CD-ROM, and a DVD. In addition, there can be a plurality of memories (1410). In addition, according to one embodiment, the memory (1410) can store a program for performing the aforementioned antenna array adjustment method.

[0110] FIG. 15 is a drawing for explaining the structure of a terminal according to various embodiments of the present disclosure.

[0111] As illustrated in FIG. 15, the terminal of the present disclosure may include a processor (1520), a transceiver (1500), and a memory (1510). However, the components of the terminal are not limited to the examples described above. For example, the terminal may include more or fewer components than the components described above. Furthermore, the processor (1520), the transceiver (1500), and the memory (1510) may be implemented in the form of a single chip.

[0112] According to one embodiment of the present disclosure, the processor (1520) may control a series of processes by which the terminal may operate according to the above-described embodiments of the present disclosure. For example, the processor (1520) may control components of the terminal to perform a method for providing an antenna array adjustment method according to the above-described embodiments. The processor (1520) may control components of the terminal to perform the above-described embodiments of the present disclosure by executing a program stored in the memory (1510). In addition, the processor (1520) may be an Application Processor (AP), a Communication Processor (CP), a circuit, an application-specific circuit, or at least one processor.

[0113] According to one embodiment of the present disclosure, a transceiver (1500) can transmit and receive signals with a network entity, another terminal, or a base station. The signals transmitted and received with the network entity, another terminal, or a base station can include control information and data. The transceiver (1500) can be configured with an RF transmitter that up-converts and amplifies the frequency of a transmitted signal, and an RF receiver that low-noise amplifies and frequency-converts a received signal. However, the transceiver (1500) is only one embodiment, and the components of the transceiver (1500) are not limited to the RF transmitter and RF receiver. In addition, the transceiver (1500) can receive a signal through a wireless channel, output it to the processor (1520), and transmit the signal output from the processor (1520) through the wireless channel.

[0114] According to one embodiment of the present disclosure, the memory (1510) can store programs and data necessary for the operation of the terminal. In addition, the memory (1510) can store control information or data included in signals transmitted and received by the terminal. The memory (1510) can be configured as a storage medium or a combination of storage media, such as a ROM, a RAM, a hard disk, a CD-ROM, and a DVD. In addition, there can be a plurality of memories (1510). In addition, according to one embodiment, the memory (1510) can also store a program for performing the aforementioned antenna array adjustment method.

[0115] The methods according to the embodiments described in the claims or specification of the present invention may be implemented in the form of hardware, software, or a combination of hardware and software.

[0116] When implemented in software, a computer-readable storage medium storing one or more programs (software modules) may be provided. The one or more programs stored in the computer-readable storage medium are configured for execution by one or more processors within an electronic device. The one or more programs include instructions that cause the electronic device to execute methods according to the embodiments described in the claims or specification of the present invention.

[0117] These programs (software modules, software) may be stored in random access memory, non-volatile memory including flash memory, read only memory (ROM), electrically erasable programmable read only memory (EEPROM), magnetic disc storage device, compact disc ROM (CD-ROM), digital versatile discs (DVDs) or other forms of optical storage device, magnetic cassette. Or, they may be stored in a memory configured as a combination of some or all of these. In addition, each configuration memory may be included in multiple numbers.

[0118] Additionally, the program may be stored in an attachable storage device that is accessible via a communication network such as the Internet, an intranet, a local area network (LAN), a wide local area network (WLAN), a storage area network (SAN), or a combination thereof. Such a storage device may be connected to a device implementing an embodiment of the present invention via an external port. Additionally, a separate storage device on the communication network may be connected to a device implementing an embodiment of the present invention.

[0119] In the specific embodiments of the present invention described above, components included in the invention are expressed in the singular or plural form depending on the specific embodiment presented. However, the singular or plural expressions are selected to suit the presented situation for convenience of explanation, and the present invention is not limited to singular or plural components. Even components expressed in the plural form may be composed of singular elements, or even components expressed in the singular form may be composed of plural elements.

[0120] While the detailed description of the present invention has described specific embodiments, it is clear that various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims but also by equivalents thereof.

Claims

1. In a method performed by a terminal in a wireless communication system, A step of transmitting a beam failure recovery request (BFRQ) to a second base station of a second cell when a beam failure occurs for a first base station of a first cell; and A step of performing a handover for the second cell when the beam failure recovery (BFR) for the second cell fails by a first value or more, The above first cell is a serving cell of the terminal, A method wherein the second cell comprises a first target cell or at least one candidate cell for the handover.

2. In paragraph 1, the method: If the BFR for the second cell fails by more than the first value, a step of identifying the third cell; and Further comprising a step of performing a handover to the third cell when the BFR for the third cell fails by a value greater than or equal to the second value, The above third cell is the second target cell for handover, A method wherein the first value and the second value are cut off values ​​for the number of attempts of BFR.

3. In paragraph 1, the method: A step of receiving setting information regarding a beam RS (reference signal) from the first base station; and A method further comprising a step of identifying a beam associated with the second cell based on the configuration information regarding the beam RS.

4. In the third paragraph, the method: A method further comprising the step of receiving, from the first base station, at least one of measurement settings for measuring the beam RS or information on radio resources for BFR for the second cell.

5. In a method performed by a second base station of a wireless communication system, When a beam failure occurs for the first base station of the first cell, a step of receiving a beam failure recovery request (BFRQ) from the terminal; and Including a step of performing a handover for a terminal when the beam failure recovery (BFR) for the second cell fails by a first value or more, The above first cell is a serving cell of the terminal, A method, wherein the second cell including the second base station includes a first target cell or at least one candidate cell for the handover.

6. In paragraph 5, If the BFR for the second cell fails by more than the first value, the BFR for the third cell is initiated. The above third cell is the second target cell for handover, A method wherein the first value is a cut off value for the number of attempts of BFR.

7. In paragraph 5, the method: Further comprising a step of transmitting setting information regarding beam RS (reference signal) to the first base station, A method wherein, based on the configuration information regarding the beam RS, the beam associated with the second cell is based on the configuration information regarding the beam RS.

8. In paragraph 5, the method: A method further comprising the step of transmitting, to the first base station, at least one of measurement settings for measuring the beam RS or information regarding radio resources for BFR for the second cell.

9. At the terminal: At least one transceiver; At least one processor communicatively coupled to said at least one transceiver; and At least one memory communicatively coupled to said at least one processor and storing instructions, The above instructions are executed individually or in any combination by the at least one processor, so that the terminal: When a beam failure occurs for the first base station of the first cell, a beam failure recovery request (BFRQ) is transmitted to the second base station of the second cell, and If the BFR (beam failure recovery) for the second cell fails by a value greater than or equal to the first value, a handover for the second cell is performed. The above first cell is a serving cell of the terminal, A terminal, wherein the second cell includes a first target cell for the handover or at least one candidate cell.

10. In paragraph 9, the commands are: If the BFR for the second cell fails by more than the first value, identify the third cell, and If the BFR for the third cell fails by a value greater than or equal to the second value, a handover for the third cell is performed. The above third cell is the second target cell for handover, The terminal, wherein the first value and the second value are cut off values ​​for the number of attempts of BFR.

11. In paragraph 9, the commands are: Receive setting information regarding beam RS (reference signal) from the first base station, and A terminal that identifies a beam associated with the second cell based on configuration information regarding the beam RS.

12. In paragraph 9, the method: A terminal configured to receive, from the first base station, at least one of measurement settings for measuring the beam RS or information on radio resources for BFR for the second cell.

13. At the second base station: At least one transceiver; At least one processor communicatively coupled to said at least one transceiver; and At least one memory communicatively coupled to said at least one processor and storing instructions, The above instructions are executed individually or in any combination by the at least one processor so that the base station: When a beam failure occurs for the first base station of the first cell, a beam failure recovery request (BFRQ) is received from the terminal, and If the BFR (beam failure recovery) for the second cell fails by a value greater than or equal to the first value, a handover is performed for the terminal. The above first cell is a serving cell of the terminal, A second base station, wherein the second cell including the second base station includes a first target cell or at least one candidate cell for the handover.

14. In paragraph 13, If the BFR for the second cell fails by more than the first value, the BFR for the third cell is initiated. The above third cell is the second target cell for handover, The second base station, wherein the first value is a cut off value regarding the number of attempts of BFR.

15. In paragraph 13, the commands are: To the above first base station, transmit setting information regarding beam RS (reference signal), A second base station, wherein the beam associated with the second cell is based on the configuration information regarding the beam RS.

Images