Method and device for performing carrier aggregation in wireless communication system

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate beyond a 4G communication system such as LTE, and proposes a method and a device, the method comprising the steps of: receiving, from a base station, system information including time division duplex (TDD) frequency information including a TDD uplink and a TDD downlink; receiving, from the base station of a radio resource control (RRC)-connected serving cell, configuration information regarding cell measurement on a radio resource identified on the basis of the TDD frequency information; and transmitting, to the base station, a measurement report regarding the serving cell on the basis of the configuration information, wherein the serving cell includes a reference cell, and the reference cell includes a special cell (spCell) and another serving cell other than the spCell.

Description

Method and apparatus for performing carrier aggregation in a wireless communication system

[0001] The present disclosure relates to the operation of a terminal and a base station in a wireless communication system. More specifically, the present disclosure relates to a method and apparatus for performing carrier aggregation in a wireless communication system.

[0002] Looking back at the evolution of wireless communication through successive generations, technologies have been developed primarily for human-oriented services, such as voice, multimedia, and data. Following the commercialization of 5G (5th Generation) communication systems, connected devices, which have been increasing explosively, are expected to be connected to communication networks. Examples of networked objects include vehicles, robots, drones, home appliances, displays, smart sensors installed in various infrastructures, construction machinery, and factory equipment. Mobile devices are expected to evolve into various form factors, such as augmented reality glasses, virtual reality headsets, and holographic devices. In the 6G (6th Generation) era, efforts are underway to develop improved 6G communication systems to connect hundreds of billions of devices and objects to provide diverse services. For this reason, 6G communication systems are referred to as "beyond 5G" systems.

[0003] In the 6G communication system predicted to be realized around 2030, the maximum transmission speed is tera (i.e., 1,000 gigabit) bps (bit per second), and the wireless latency is 100 microseconds (μsec). In other words, compared to the 5G communication system, the transmission speed in the 6G communication system is 50 times faster, and the wireless latency is reduced to one-tenth.

[0004] To achieve such high data transmission speeds and ultra-low latency, 6G communication systems are being considered for implementation in the terahertz (THz) band (e.g., the 95 gigahertz (GHz) to 3 terahertz (3THz) band). Due to more severe path loss and atmospheric absorption phenomena compared to the millimeter wave (mmWave) band introduced in 5G, the importance of technologies capable of guaranteeing signal reach, or coverage, is expected to increase in the terahertz band. As key technologies to ensure coverage, new waveforms, beamforming, and multi-antenna transmission technologies such as massive Multiple-Input and Multiple-Output (MIMO), Full Dimensional MIMO (FD-MIMO), array antennas, and large-scale antennas must be developed. In addition, new technologies such as metamaterial-based lenses and antennas, high-dimensional spatial multiplexing technology using Orbital Angular Momentum (OAM), and Reconfigurable Intelligent Surface (RIS) are being discussed to improve coverage of terahertz band signals.

[0005] In addition, to improve frequency efficiency and system network, development is underway in 6G communication systems for full duplex technology, in which uplink and downlink simultaneously utilize the same frequency resources at the same time; network technology that integrates satellites and HAPS (High-Altitude Platform Stations); network structure innovation technology that supports mobile base stations and enables network operation optimization and automation; dynamic spectrum sharing technology through collision avoidance based on spectrum usage prediction; AI-based communication technology that utilizes AI from the design stage and internalizes end-to-end AI support functions to realize system optimization; and next-generation distributed computing technology that realizes services of complexity exceeding the limits of terminal computing capabilities by utilizing ultra-high performance communication and computing resources (Mobile Edge Computing (MEC), cloud, etc.). In addition, attempts are continuing to further strengthen connectivity between devices, further optimize networks, promote the softwareization of network entities, and increase the openness of wireless communication through the design of new protocols to be used in 6G communication systems, the implementation of hardware-based security environments, the development of mechanisms for the safe utilization of data, and the development of technologies regarding privacy maintenance methods.

[0006] Due to the research and development of such 6G communication systems, it is expected that a new dimension of hyper-connected experience will become possible through the hyper-connectivity of 6G communication systems, which encompasses not only connections between objects but also connections between people and objects. Specifically, it is projected that 6G communication systems will enable the provision of services such as truly immersive eXtended Reality (XR), high-fidelity mobile holograms, and digital replicas. Furthermore, services such as remote surgery, industrial automation, and emergency response, which are provided through 6G communication systems with enhanced security and reliability, will be applied in various fields including industry, healthcare, automotive, and home appliances.

[0007] Based on the discussion described above, the present disclosure aims to provide a method and apparatus for performing carrier aggregation in a wireless communication system.

[0008] The technical problems to be solved by the present invention are not limited to those mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art to which the present invention belongs from the description below.

[0009] According to various embodiments of the present disclosure, a method for processing a control signal in a wireless communication system may include: receiving a first control signal transmitted from a base station; processing the received first control signal; and transmitting a second control signal generated based on the processing to the base station.

[0010] One embodiment of the present invention provides a method and apparatus for effectively managing terminal capability information in a wireless communication system.

[0011] The effects obtainable from the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art to which the present disclosure belongs from the description below.

[0012] FIG. 1 is a drawing illustrating the structure of a wireless communication system according to one embodiment of the present invention.

[0013] FIG. 2 illustrates a method for determining a reference cell in a predetermined operation according to one embodiment of the present disclosure.

[0014] FIG. 3 illustrates a procedure for reporting cell measurement results based on events according to one embodiment of the present disclosure.

[0015] FIG. 4 illustrates a procedure for performing RLM (radio link monitoring) / RLF (radio link failure) operations in a predetermined serving cell according to one embodiment of the present disclosure.

[0016] FIG. 5 illustrates a procedure for changing a reference cell when an RLF occurs according to one embodiment of the present disclosure.

[0017] FIG. 6 illustrates a method for applying a dormant BWP (bandwidth part) according to one embodiment of the present disclosure.

[0018] FIG. 7 illustrates a method for performing a beam failure recovery operation according to one embodiment of the present disclosure.

[0019] FIG. 8 illustrates a method for performing random access according to one embodiment of the present disclosure.

[0020] FIG. 9 illustrates a method for setting a time division duplex (TDD) according to one embodiment of the present disclosure.

[0021] FIG. 10 is a flowchart of terminal operation according to one embodiment of the present disclosure.

[0022] FIG. 11 is a flowchart of a cell operation according to one embodiment of the present disclosure.

[0023] FIG. 12 is a block diagram illustrating the internal structure of a terminal according to one embodiment of the present disclosure.

[0024] FIG. 13 is a block diagram showing the configuration of a base station according to one embodiment of the present disclosure.

[0025] In describing the present disclosure below, if it is determined that a detailed description of related known functions or configurations could unnecessarily obscure the essence of the present disclosure, such detailed description will be omitted. Furthermore, the terms described below are defined in consideration of their functions in the present disclosure, and these may vary depending on the intentions or practices of the user or operator. Therefore, such definitions should be based on the content throughout this specification. The advantages and features of the present disclosure, and the methods for achieving them, will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below but may be implemented in various different forms; these embodiments are provided merely to ensure that the disclosure is complete and to fully inform those skilled in the art of the scope of the invention, and the present disclosure is defined only by the scope of the claims. Throughout the specification, the same reference numerals may refer to the same components.

[0026] At this point, it will be understood that each block of the process flow diagrams and combinations of the flow diagrams can be executed by computer program instructions. Since these computer program instructions can be loaded into the processor of a general-purpose computer, a special-purpose computer, or other programmable data processing equipment, the instructions executed through the processor of the computer or other programmable data processing equipment create means to perform the functions described in the flow diagram block(s). Since these computer program instructions can also be stored in computer-available or computer-readable memory that can be directed toward the computer or other programmable data processing equipment to implement the function in a specific way, the instructions stored in computer-available or computer-readable memory can also produce a manufactured item containing instruction means to perform the function described in the flow diagram block(s). Since computer program instructions can be loaded onto a computer or other programmable data processing equipment, instructions that perform a series of operation steps on the computer or other programmable data processing equipment to create a process executed by the computer can also provide steps for executing the functions described in the flowchart block(s).

[0027] Additionally, each block may represent a module, segment, or part of code containing one or more executable instructions for executing a specified logical function(s). It should also be noted that in some alternative execution examples, the functions mentioned in the blocks may occur out of order. For example, two blocks described in succession may actually be executed substantially simultaneously, or the blocks may sometimes be executed in reverse order according to their corresponding functions.

[0028] In this embodiment, the term "part" refers to a software or hardware component such as an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit), and the "part" may perform certain roles. However, the meaning of "part" is not limited to software or hardware. The "part" may be configured to reside in an addressable storage medium or configured to run one or more processors. Thus, as an example, the "part" may include components such as software components, object-oriented software components, class components, and task components, as well as processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functions provided within the components and "parts" may be combined into a smaller number of components and "parts" or further separated into additional components and "parts." In addition, the components and 'parts' may be implemented to utilize one or more CPUs within the device or secure multimedia card. Also, in the embodiments, 'parts' may include one or more processors.

[0029] In describing the present disclosure below, if it is determined that a detailed description of related known functions or configurations could unnecessarily obscure the essence of the present disclosure, such detailed description will be omitted. Embodiments of the present disclosure may be described below with reference to the attached drawings.

[0030] 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, terms referring to various identification information, etc., are examples provided for the convenience of explanation. Accordingly, the present disclosure is not limited to the terms described below, and other terms referring to objects having equivalent technical meanings may be used.

[0031] In the following description, the terms "physical channel" and "signal" may be used interchangeably with "data" or "control signal." For example, PDSCH (physical downlink shared channel) is a term referring to a physical channel through which data is transmitted, but PDSCH may also be used to refer to data. That is, in this disclosure, the expression "can transmit a physical channel" may be interpreted as equivalent to the expression "can transmit data or a signal through a physical channel."

[0032] In the present disclosure, upper signaling may refer to a signal transmission method transmitted from a base station to a terminal using a physical layer downlink data channel, or from a terminal to a base station using a physical layer uplink data channel. Upper signaling may be understood as radio resource control (RRC) signaling or a media access control (MAC) control element (CE).

[0033] For convenience of explanation, the present disclosure may use terms and names defined in the 3GPP NR (3rd Generation Partnership Project NR (New Radio)) or 3GPP LTE (3rd Generation Partnership Project Long Term Evolution) standards. However, the present disclosure is not limited by these terms and names and may be applied equally to systems conforming to other standards. In the present disclosure, gNB may be used interchangeably with eNB for convenience of explanation. That is, a base station described as an eNB may represent a gNB. Additionally, the term terminal may refer to mobile phones, MTC devices, NB-IoT devices, sensors, as well as other wireless communication devices.

[0034] Hereinafter, the base station is an entity that performs resource allocation for terminals and may be at least one of a gNodeB (gNB), eNode B (eNB), NodeB, BS (Base Station), wireless access unit, base station controller, or a node on a network. The terminal may include a UE (User Equipment), MS (Mobile Station), cellular phone, smartphone, computer, or a multimedia system capable of performing communication functions. Of course, it is not limited to examples.

[0035] In particular, the present disclosure is applicable to 3GPP NR (5th generation mobile communication standard). Furthermore, the present disclosure is applicable to intelligent services based on 5G communication technology and IoT-related technology (e.g., smart home, smart building, smart city, smart car or connected car, healthcare, digital education, retail, security and safety-related services, etc.). In the present disclosure, eNB may be used interchangeably with gNB for convenience of explanation. That is, a base station described as eNB may represent a gNB. Additionally, the term terminal may refer to mobile phones, NB-IoT devices, sensors, as well as other wireless communication devices.

[0036] Wireless communication systems are evolving from providing early voice-oriented services to broadband wireless communication systems that provide high-speed, high-quality packet data services, such as communication standards like 3GPP’s HSPA (High Speed ​​Packet Access), LTE (Long Term Evolution or E-UTRA (Evolved Universal Terrestrial Radio Access)), LTE-Advanced (LTE-A), LTE-Pro, 3GPP2’s HRPD (High Rate Packet Data), UMB (Ultra Mobile Broadband), and IEEE’s 802.16e.

[0037] As a representative example of a broadband wireless communication system, the LTE system employs the Orthogonal Frequency Division Multiplexing (OFDM) method for the downlink (DL) and the Single Carrier Frequency Division Multiple Access (SC-FDMA) method for the uplink (UL). The uplink refers to a wireless link through which a terminal (User Equipment; UE or Mobile Station; MS) transmits data or control signals to a base station (eNode B or BS; Base Station), and the downlink refers to a wireless link through which a base station transmits data or control signals to a terminal. Multiple access methods such as this can distinguish the data or control information of each user by allocating and operating time-frequency resources to be sent for each user so that they do not overlap, that is, so that orthogonality is established.

[0038] As a future communication system following LTE, that is, a 5G communication system, it must be able to freely reflect the diverse requirements of users and service providers, and therefore, services that satisfy various requirements simultaneously may need to be supported. Services being considered for the 5G communication system include Enhanced Mobile Broadband (eMBB), Massive Machine Type Communication (mMTC), and Ultra Reliability Low Latency Communication (URLLC).

[0039] According to some embodiments, eMBB may aim to provide data transmission speeds that are higher than those supported by existing LTE, LTE-A, or LTE-Pro. For example, in a 5G communication system, eMBB may need to be able to provide a peak data rate of 20 Gbps in the downlink and a peak data rate of 10 Gbps in the uplink from the perspective of a single base station. In addition, the 5G communication system may need to provide a user-perceived data rate while simultaneously providing the peak data rate. To satisfy these requirements, the 5G communication system may require improvements in various transmission and reception technologies, including enhanced Multi-Input Multi-Output (MIMO) transmission technology. Furthermore, while current LTE transmits signals using a maximum transmission bandwidth of 20 MHz in the 2 GHz band, the 5G communication system may satisfy the data transmission speeds required by the 5G communication system by using a frequency bandwidth wider than 20 MHz in frequency bands of 3 to 6 GHz or above 6 GHz.

[0040] Simultaneously, mMTC is being considered to support application services such as the Internet of Things (IoT) in 5G communication systems. To efficiently provide IoT services, mMTC may require support for a large number of terminal connections within a cell, improved terminal coverage, enhanced battery life, and reduced terminal costs. Since IoT devices are attached to various sensors and equipment to provide communication functions, it may be necessary to support a large number of terminals within a cell (e.g., 1,000,000 terminals / km²). Furthermore, due to the nature of the service, terminals supporting mMTC are likely to be located in dead zones not covered by cells, such as building basements; therefore, wider coverage may be required compared to other services provided by 5G communication systems. Terminals supporting mMTC must consist of low-cost devices, and since it is difficult to frequently replace terminal batteries, a very long battery life of 10 to 15 years may be required.

[0041] Finally, URLLC is a mission-critical cellular-based wireless communication service that can be used for services such as remote control of robots or machinery, industrial automation, unmanned aerial vehicles, remote health care, and emergency alerts. Therefore, the communication provided by URLLC may need to offer very low latency and very high reliability. For example, services supporting URLLC must satisfy an air interface latency of less than 0.5 milliseconds and may simultaneously require a packet error rate of 10⁻⁵ or less. Consequently, for services supporting URLLC, 5G systems must provide a Transmit Time Interval (TTI) smaller than other services, and design considerations may be required to allocate wide resources in the frequency band to ensure the reliability of the communication link.

[0042] The three services considered in the aforementioned 5G communication system, namely eMBB, URLLC, and mMTC, can be multiplexed and transmitted within a single system. In this case, different transmission and reception techniques and parameters may be used between the services to satisfy the different requirements of each service. However, the aforementioned mMTC, URLLC, and eMBB are merely examples of different service types, and the service types to which the present disclosure applies are not limited to the examples mentioned above.

[0043] In addition, although embodiments of the present disclosure are described below using LTE, LTE-A, LTE Pro, or 5G (or NR, next-generation mobile communication) systems as examples, embodiments of the present disclosure may be applied to other communication systems having similar technical backgrounds or channel types. Furthermore, embodiments of the present disclosure may be applied to other communication systems with some modifications made at the discretion of a person with skilled technical knowledge, without significantly departing from the scope of the present disclosure. Although the present disclosure is based on an LTE system, it is also applicable to other mobile (or wireless) communication systems, such as NR, which is a next-generation mobile (or wireless) communication system. For example, in the present disclosure, the eNB in ​​LTE may correspond to the gNB in ​​NR, and the MME in LTE may correspond to the AMF in NR.

[0044] FIG. 1 is a drawing illustrating the structure of a wireless communication system according to one embodiment of the present disclosure.

[0045] Referring to FIG. 1, as illustrated, the wireless access network of a wireless communication (or mobile communication) system (New Radio, NR) consists of a next-generation base station (New Radio Node B, hereinafter gNB) (110) and a wireless core network (new radio core network), and the wireless core network may include an AMF (105, access and mobility management function). Of course, the configuration of the wireless access network is not limited to the example described above. A user terminal (New Radio User Equipment, hereinafter NR UE or terminal) (115) connects to an external network through the gNB (110) and the AMF (105).

[0046] In FIG. 1, the gNB corresponds to the eNB (Evolved Node B) of the existing LTE system. The gNB is connected to the NR UE via a wireless channel and can provide superior service compared to the existing Node B (e.g., LTE base station) (120). In a wireless communication system, since all user traffic is serviced through a shared channel, a device is required to collect state information such as the buffer status, available transmission power status, and / or channel status of the UEs and perform scheduling, and this is handled by the gNB (110). A single gNB typically controls multiple cells. To achieve ultra-high-speed data transmission compared to existing LTE, it can have a maximum bandwidth greater than the existing maximum bandwidth, and additional beamforming technology can be incorporated by using Orthogonal Frequency Division Multiplexing (hereinafter referred to as OFDM) as the wireless access technology. In addition, according to one embodiment of the present disclosure, the gNB (110) applies an Adaptive Modulation & Coding (hereinafter referred to as AMC) method that determines a modulation scheme and a channel coding rate according to the channel conditions of the terminal. The AMF (105) performs functions such as mobility support, bearer configuration, and QoS (quality of service) configuration. The AMF (105) is a device responsible for various control functions as well as mobility management functions for the terminal and is connected to multiple base stations. In addition, the next-generation mobile communication system can be interconnected with the existing LTE system, and the AMF is connected to the MME (125) via a network interface. The MME (125) is connected to the existing base station, eNB (130). A terminal supporting LTE-NR Dual Connectivity can transmit and receive data while maintaining a connection to both the gNB and the eNB (135).

[0047] In LTE and NR, a specific reference cell, known as a Special Cell (SpCell), specifically a Primary Cell (PCell) or Primary SCG Cell (PSCell), is defined. The PCell is the cell that a terminal in standby or inactive mode can camp on and is the target of cell reselection operations. When a terminal in connection mode performs a handover or SCG change operation, the signal strength of the PCell and PSCell is considered, and the System Frame Number (SFN) and subframe timing of these cells serve as temporal reference points for the execution of various connection mode operations. Furthermore, if the signal strength of the cells is not satisfactory, the terminal considers the wireless link connection of the Master Cell Group (MCG) or Secondary Cell Group (SCG) to have failed. In Carrier Aggregation (CA) or Dual Connectivity (DC), multiple serving cells can be configured for a single terminal, and serving cells excluding the PCell or PSCell are referred to as SCells. Even if the signal strength of the above SCell is not good, the terminal does not consider the wireless link connection to have failed.

[0048] In 6G, proposals are being discussed to eliminate the distinction between the SpCell and SCell in CA or DC scenarios. This may mean allowing the SCell to perform the role of a predefined SpCell, or to easily change the role of the SpCell from one serving cell to another through a specific instruction. The above specific instruction may be provided to the terminal through a specific RRC message or L1 / L2 signaling.

[0049] Meanwhile, in the following description, the base station or network may be indicated as iNB (e.g., eNB or gNB) in the drawings.

[0050] FIG. 2 illustrates a method for determining a reference cell in a predetermined operation according to one embodiment of the present disclosure.

[0051] The SFN and subframe timing of a SpCell can serve as a temporal reference point for the execution of various connection mode operations. For example, a SpCell may be a reference cell for specific operations. For example, a measurement gap may be a time interval during which a terminal temporarily suspends data transmission and reception to measure adjacent frequencies. The said time interval set by the network may be determined based on the SFN and subframe timing of a specific cell indicated by the network. If no indicated cell exists, the SFN and subframe timing of a PCell may be considered. SMTC (SS / PBCH block Measurement Timing Configuration) and RMTC (RSSI Measurement Timing Configuration) may be configuration information indicating an SMTC occasion or an RMTC occasion. A terminal receiving said configuration information may determine the location of said occasion based on the SFN and subframe timing of the SpCell. Even in the DRX (Discontinuous Reception) function configured to reduce terminal power consumption, the SFN of the SpCell can be used as a reference to determine the DRX period and offset for the terminal.

[0052] A terminal (205) in a standby mode or idle mode (e.g., RRC_idle) or inactive mode (e.g., RRC_inactive) is camp-on to a cell (210) (e.g., eNB or gNB) and performs an RRC establishment operation (215) to connect to said cell.

[0053] The terminal (205) that has switched to a connection mode (e.g., RRC_connected) state may regard the cell as a default reference cell. As another example, the default reference cell may be a serving cell acting as an SpCell, or a serving cell transmitting a CD-SSB (Cell Defined-SSB). When the terminal (205) performs the operations described above (e.g., at least one of measurement gap, SMTC, RMTC, or DRX), if there is no specific instruction from the network, the SFN or subframe timing of the default reference cell may be considered to determine the necessary temporal points (220).

[0054] The network (210) can provide a plurality of serving cells by setting a CA or DC function to the terminal (205) (225).

[0055] The above network (210) can set a certain serving cell as a reference cell (230) by using a certain RRC message or L1 (layer 1) / L2 (layer 2) signaling. At this time, the RRC message or L1 / L2 signaling may include the identity (ID) of the reference cell.

[0056] The above reference cell may be designated differently for a specific operation (e.g., at least one of measurement gap, SMTC, RMTC, or DRX), feature, TAG (Timing Advance Group), or CG (Cell Group). When the terminal performs a specific operation, it may use the timing of the SFN or subframe of the indicated reference cell (e.g., ) (235). If the indicated reference cell is no longer valid, the timing of the SFN or subframe of the default reference cell may be applied without separate instruction.

[0057] FIG. 3 illustrates a procedure for reporting cell measurement results based on events according to one embodiment of the present disclosure.

[0058] The base station (310) can provide a plurality of serving cells to the terminal (305) by setting the CA or DC function (315).

[0059] The base station (310) can set an Event-triggered cell measurement operation for the terminal (305) (320). In this embodiment, the following new event is proposed. In existing systems, when a terminal in connection mode performs a handover or SCG change operation, only the signal strength of SpCell cells is considered, but the proposed new events are intended to support the consideration of all set or activated serving cells.

[0060] - Event A3x: Neighbor becomes amount of offset better than Serving (When the offset of the neighboring cell is greater than that of the serving cell)

[0061] - Event A5x: Serving becomes worse than absolute threshold1 AND Neighbor becomes better than another absolute threshold2 (Case where the serving cell becomes worse than absolute threshold1 and the neighbor cell becomes better than another absolute threshold2)

[0062] In the above event, “Serving” may refer to the Reference Signal Received Power (RSRP) or Reference Signal Received Quality (RSRQ) of a predetermined configured serving cell or all configured or active serving cells. “Neighbor” may refer to the RSRP or RSRQ of a predetermined adjacent cell. The offset, threshold1, and threshold2 may be predetermined threshold values ​​provided by the network.

[0063] The terminal (305) evaluates whether the above-mentioned pre-set events are satisfied (325), and if the event is satisfied, it can transmit a MeasurementReport message containing cell measurement results to the base station (310) (330).

[0064] FIG. 4 illustrates a procedure for performing RLM (Radio Link Monitoring) / RLF (Radio Link Failure) operations in a predetermined serving cell according to one embodiment of the present disclosure.

[0065] In a wireless communication system, a terminal measures the signal strength of a SpCell to evaluate the state of the wireless link and determines whether the wireless link is sufficiently good for normal communication services. This is referred to as RLM / RLF.

[0066] In an RLM operation, the terminal physical layer can measure the downlink signal quality from the RS (Reference Signal) of the serving cell. The terminal can determine whether the signal quality is lower than a specific threshold value (e.g., Qout). The threshold value may be a signal quality value corresponding to a specific BLER (block error rate) measured in the PDCCH (physical downlink control channel). If the signal quality is lower than the specific threshold value (Qout), the physical layer can transmit an 'out-of-sync' indicator to the upper layer. If the indicator is transmitted to the upper layer more than a certain number of times, the upper layer can start a specific timer, and when the timer expires, declare an RLF.

[0067] In the RLF operation, as previously explained, the RLF can be declared based on the result from the RLM. The terminal physical layer can determine at specific intervals (e.g., Qout evaluation period) whether the downlink signal quality from the serving cell's RS is lower than a specific threshold (Qout). If the signal quality is lower than the specific threshold (Qout), the physical layer can transmit an 'out-of-sync' indicator to the upper layer. After the minimum indicator is transmitted to the upper layer, a specific timer (e.g., T310) may be activated when it is transmitted to the upper layer a specific number of times (e.g., N310). The physical layer can also determine whether the downlink signal quality from the serving cell's RS is higher than a specific threshold (e.g., Qin). If the signal quality is higher than the specific threshold (Qin), the physical layer can transmit an 'in-sync' indicator to the upper layer. When the above indicator is transmitted to the upper layer a specific number of times, the upper layer may stop the running T310 timer. If the T310 timer expires without being stopped, the upper layer may declare an RLF. After declaring the RLF, the terminal may start another timer (e.g., T311). The terminal may search for a new suitable cell, and if it fails to find one by the time when T311 expires, it may switch to standby mode. If the terminal finds a new suitable cell before the timer expires, it may start the T301 timer and perform a re-establishment process with the cell. If the re-establishment is not successfully completed before the T301 timer expires, the terminal may switch to standby mode. If the re-establishment is successful, the terminal may maintain a connection mode with the cell.RLF may be declared by the above RLM operation and may be declared according to other conditions. RLF may also be declared if random access fails. Additionally, RLF may be declared if the maximum number of retransmissions is reached at the RLC (radio link control) layer, or if the packet is not successfully delivered. The description of the above T301 and T311 operations may be as shown in Table 1 below. Of course, it is not limited to the examples below.

[0068]

[0069] Another case in which an RLF is declared may be when a handover fails. When the terminal receives an RRCConnectionReconfiguration message containing handover configuration information and / or mobilityControlInfo IE, it may start a T304 timer. The value of the T304 timer may be provided by the mobilityControlInfo. If random access to the target cell is not successfully completed before the timer expires, the terminal may consider the handover to have failed and declare an RLF.

[0070] In this embodiment, the RLM / RLF operation is performed on a predetermined configured serving cell or all serving cells, rather than on an SpCell. The terminal (405) may receive configuration information related to the RLM / RLF operation from the base station (410) (415). The configuration information may additionally include information on the serving cells considered for the RLM / RLF operation, along with the aforementioned existing information. The configured serving cells may be indicated as a single or multiple cells, or at least one of a predetermined cell group may be indicated. If the cell indication information is not configured, the reference cell may be considered as default, or all configured or activated serving cells may be applied.

[0071] The terminal (405) can measure the downlink signal quality from the RS of all serving cells or a predetermined pre-configured serving cell based on the received configuration information. The terminal (405) can determine whether the signal quality of each serving cell is lower than a specific threshold value (Qout). If the signal quality is lower than the specific threshold value (Qout), the physical layer can transmit an 'out-of-sync' indicator to the upper layer (420). If the indicator is transmitted to the upper layer more than a certain number of times in the physical layers of all serving cells performing the RLM, the upper layer can start a specific timer, and when the timer expires, declare an RLF (425). For example, for all serving cells performing the RLM, if the condition for declaring an RLF is satisfied, the terminal (405) can declare an RLF. If, before the above timer expires, an 'in-sync' indicator is transmitted to the upper layer a specific number of times from the physical layer of at least one serving cell, the upper layer can stop the running timer.

[0072] The terminal (405) that has declared RLF can trigger an RRC re-establishment operation (430). If in a DC state, the terminal (405) may also perform a fast MCG link recovery operation. In another embodiment, for each serving cell performing the RLM, if the indicator is transmitted to the upper layer more than a certain number of times, the upper layer activates a specific timer corresponding to the cell, and when the timer expires, it can declare an RLF for the cell. At this time, the terminal (405) can report the RLF of the specific cell to the base station (410), and the base station (410) that receives the report can assign the role of SpCell to the serving cell where the RLF has not been declared. The terminal (405) can trigger an RRC re-establishment operation only when RLF has been declared in all serving cells.

[0073] FIG. 5 illustrates a procedure for changing a reference cell when an RLF occurs according to one embodiment of the present disclosure.

[0074] The terminal (505) can receive data transmission and reception services by having CA set up with a plurality of serving cells (510, 515, 520) (525).

[0075] One of the above serving cells (510, 515, 520) can perform the role of a PCell. While the terminal (505) is receiving data transmission and reception services from the above serving cells (510, 515, 520), it can identify that there is a problem with the wireless link with the serving cell (510) performing the role of the PCell (530, 535).

[0076] The terminal (505) may report to the serving cell (515) that there is a problem with the connection to the serving cell (510) performing the role of the PCell (540). At this time, the signal measurement results of the serving cells may also be reported. For the report, a predetermined RRC message or L1 / L2 signaling may be used. Along with the report, the terminal (505) may activate a predetermined timer.

[0077] The network that receives the above report may switch the PCell role to another serving cell. The network may notify the terminal (505) that the PCell role has been switched to a specific serving cell (515) having a good wireless link state by using a specific RRC message or L1 / L2 signaling (545). Upon receiving the configuration information, the terminal (505) may stop the running timer and apply the PCell role to the indicated serving cell (515) from a specific point in time. If the configuration information instructing the switch is not received until the running timer expires, the terminal (505) may consider the connection to have failed and trigger an RRC re-establishment operation. In addition to switching the PCell role to another serving cell, the network may hand over the terminal (505) or set an RRC Release (release of connection mode), and upon receiving the handover configuration information or the RRC Release message, the terminal (505) may stop the running timer.

[0078] FIG. 6 illustrates a method of applying dormant BWP according to one embodiment of the present disclosure.

[0079] dormant BWP, introduced for terminal power saving in existing NR systems, is not supported in SpCell and PUCCH (physical uplink control channel) SCells. Therefore, NR base stations do not provide dormant BWP configuration information for SpCells or PUCCH SCells.

[0080] In this embodiment, the base station can provide dormant BWP configuration information for all serving cells, and is characterized by temporarily suspending the dormant BWP applied to a serving cell when a serving cell is configured to perform the role of a PCell. This method allows the dormant BWP configuration information previously set for the serving cell performing the PCell role to be quickly applied when the serving cell performing the PCell role changes.

[0081] The terminal (605) can receive dormant BWP configuration information for all serving cells from the base station (610) (615). One of the serving cells can perform the role of a PCell when a certain condition is satisfied or according to instructions from the network.

[0082] The above terminal (605) may not apply dormant BWP setting information to the serving cell that performs the PCell role, even though dormant BWP setting information corresponding to the serving cell is provided (620).

[0083] FIG. 7 illustrates a method for performing a beam failure recovery operation according to one embodiment of the present disclosure.

[0084] In a conventional NR system, when a terminal detects a certain number of consecutive beam reception failures in a serving cell, it transmits a Beam Failure Recovery (BFR) MAC (medium access control) CE (control element), which is an L2 signaling, to the base station. The BFR MAC CE includes indicator information of the serving cell where the beam reception failure occurred and certain good beam information (candidate RS ID). Upon receiving this, the base station can readjust the existing beam to the good beam reported by the terminal. However, if the serving cell is an SpCell, the terminal can transmit the BFR MAC CE to the base station through a random access procedure. In this embodiment, when a consecutive beam reception failure occurs in a serving cell acting as a PCell, the terminal reports a BFR MAC CE indicating the consecutive beam reception failure to another valid serving cell. If a certain number of consecutive beam reception failures are detected in all serving cells, the terminal can perform a random access to a certain serving cell and transmit the BFR MAC CE to the base station.

[0085] A terminal (705) can receive data transmission and reception services by establishing CA with a plurality of serving cells (710, 715, 720) (725). One of the serving cells (710, 715, 720) can perform the role of a PCell. While the terminal (705) is receiving data transmission and reception services with the serving cells (710, 715, 720), it recognizes that there is a problem with continuous beam reception (730) with the serving cell (710) performing the role of the PCell (730, 735).

[0086] The terminal (705) can transmit a BFR MAC CE to a certain serving cell (715) that maintains a good beam reception state (740). Upon receiving the BFR MAC CE, the base station (715) can reset the beam of the serving cell (710) performing the PCell role, or assign the PCell role to another serving cell providing a good beam.

[0087] Meanwhile, the terminal (705) can detect a predetermined consecutive beam reception failure (745) in all serving cells (710, 715, 720) (745, 750).

[0088] The above terminal (705) can trigger a random access procedure and transmit to a specific serving cell, including indicator information in msg3 indicating that a BFR MAC CE or a continuous beam reception failure has occurred in all serving cells (710, 715, 720) (755).

[0089] FIG. 8 illustrates a method for performing random access according to one embodiment of the present disclosure.

[0090] In existing mobile communication systems, random access is typically performed in a PCell. In the 4-step CBRA (Contention-Based Random Access) procedure, the terminal performs the first three steps in the PCell, and the final contention resolution step in the PCell or in a designated SCell that cross-schedules the PCell. 2-step RA (Random Access) is performed in the PCell, and the final contention resolution step is performed in the PCell or in a designated SCell that cross-schedules the PCell. The CFRA (Contention-Free Random Access) procedure is performed in the PCell. When a STAG (Secondary Timing Advance Group) is established, CFRA may be performed in a designated SCell. In this case, the terminal transmits a preamble to a single SCell according to the PDCCH order received from the base station, but from the reception of the RAR (random access response), it still performs in the PCell.

[0091] In the present embodiment, the terminal determines the serving cell for performing random access according to predetermined conditions. For example, the terminal may perform the random access procedure in a cell selected for camp-on in standby mode or inactive mode, a serving cell acting as an SpCell, or a serving cell broadcasting CD-SSB. Additionally, the base station may indicate the serving cell where random access is performed through a PDCCH order. In this case, unlike conventional systems, the embodiment of the present disclosure may be characterized in that not only the preamble transmission but also subsequent procedures are performed in the indicated serving cell. The above-described feature may mitigate or resolve the problem of random access procedures being concentrated in a specific cell.

[0092] The terminal (805) can receive data transmission and reception services by having CA set up with a plurality of serving cells (810, 815) (820).

[0093] The base station (810) may determine that a TA update is required for serving cells belonging to a predetermined TAG (825).

[0094] The base station (810) can select a specific serving cell belonging to the TAG and transmit a PDCCH order containing an indicator that directs the serving cell to the terminal (805) (830).

[0095] The terminal (805) that receives the above PDCCH order can transmit a preamble to the serving cell (815) indicated in the above PDCCH order (835).

[0096] The terminal (805) can receive a RAR message from the serving cell (815) that transmitted the preamble (840).

[0097] The terminal (805) that receives the above RAR message can send a msg3 message to the serving cell (815) (845).

[0098] The terminal (805) may receive a msg4 message from the serving cell (815) or receive a msg4 message from another serving cell indicated by the serving cell (815) (850).

[0099] In another embodiment, the network may instruct the terminal (805) to a serving cell where the procedures following the preamble transmission in the random access procedure (RAR reception, msg3 transmission, msg4 reception) will take place, through predetermined configuration information. The predetermined configuration information may be included in a predetermined RRC message or the PDCCH order.

[0100] FIG. 9 illustrates a method for setting Time Division Duplex (TDD) according to one embodiment of the present disclosure.

[0101] TDD is a duplex method in which both the downlink and uplink operate in a time-division manner within a designated frequency band. In existing mobile communication systems, since corresponding downlinks and uplinks exist within the same frequency band, it is sufficient to provide the terminal with information regarding the TDD frequency band (e.g., frequency band). On the other hand, in 6G, a downlink may exist in the first TDD frequency band and an uplink in the second TDD frequency band. Therefore, even though it is a TDD method, it is necessary to provide the downlink frequency and uplink frequency to the terminal.

[0102] Accordingly, the base station can provide the terminal (905) with the TDD downlink frequency information as well as the corresponding TDD uplink frequency (920) by using system information or RRC dedicated signaling transmitted on the downlink frequency (910). At this time, the received configuration information (920) may include time pattern information used as a downlink or uplink at each of the TDD downlink and TDD uplink frequencies. The terminal (905) that receives the TDD frequency information can receive downlink control signals and data in a pre-configured time interval in the indicated downlink TDD frequency band (925).

[0103] The above terminal (905) can transmit uplink control signals and data in a preset time interval of the indicated uplink TDD frequency band (930).

[0104] FIG. 10 is a flowchart of terminal operation according to one embodiment of the present disclosure.

[0105] In step 1005, the terminal can receive TDD downlink and TDD uplink frequency information broadcast from the base station.

[0106] In step 1010, the terminal can recognize the frequency and time interval for receiving downlink control signals and data and the frequency and time interval for transmitting uplink control signals and data based on the received TDD frequency information.

[0107] In step 1015, the terminal performs an RRC establishment operation on a predetermined serving cell to switch to a connection mode state, at which time the serving cell may be considered as a default reference cell.

[0108] In step 1020, when the terminal performs operations such as measurement gap, SMTC, RMTC, and DRX, it can determine necessary time points (or reference points) related to time by considering the SFN or subframe timing of the default reference cell.

[0109] In step 1025, the terminal may receive a specific RRC message or L1 / L2 signaling (e.g., system information block, SIB) from the base station indicating a specific serving cell as a reference cell.

[0110] In step 1030, when the terminal performs operations such as measurement gap, SMTC, RMTC, DRX, etc., it may determine necessary time points (or reference points) related to time by considering the SFN or subframe timing of the indicated cell.

[0111] In step 1035, the terminal can receive configuration information related to a new Event-triggered cell measurement.

[0112] In step 1040, the terminal may evaluate whether the new event condition is satisfied by considering the signal strength of a predetermined set serving cell or all set or activated serving cells instead of the existing SpCell.

[0113] In step 1045, if the event condition is satisfied, the terminal can send a MeasurementReport message to the base station.

[0114] In step 1050, the terminal can receive setting information for an RLM / RLF operation to be performed in a predetermined set serving cell or all serving cells from the base station.

[0115] In step 1055, the terminal can perform RLM / RLF operations in a predetermined configured serving cell or all serving cells.

[0116] In step 1060, the terminal can recognize that an RLF has occurred in the serving cell performing the role of a PCell.

[0117] In step 1065, the terminal may report to the base station that there is a problem with the connection of the serving cell performing the role of the PCell.

[0118] In step 1070, the terminal may receive a specific RRC message or L1 / L2 signaling from the base station instructing it to switch the PCell role to a specific serving cell having a good wireless link state.

[0119] In step 1075, the terminal can receive dormant BWP configuration information for all serving cells from the base station.

[0120] In step 1080, the terminal is provided with dormant BWP configuration information corresponding to the serving cell instructed to perform the PCell role, but does not apply the dormant BWP configuration information to the instructed serving cell.

[0121] In step 1085, the terminal can recognize that there is a problem with continuous beam reception with the serving cell performing the role of the PCell, and can report the problem with continuous beam reception to the base station through a predetermined MAC CE.

[0122] In step 1090, the terminal may reset the beam of the serving cell performing the PCell role, or assign the PCell role to another serving cell providing a good beam.

[0123] In step 1095, the terminal may receive a PDCCH order from the base station that includes an indicator indicating a specific serving cell.

[0124] In step 1100, the terminal can transmit a preamble to the serving cell indicated in the PDCCH order.

[0125] In step 1105, the terminal can receive a RAR message from the serving cell that transmitted the preamble.

[0126] In step 1110, the terminal can send a msg3 message to the serving cell that provided the RAR message.

[0127] In step 1115, the terminal may receive a msg4 message from the serving cell or receive a msg4 message from another serving cell indicated by the serving cell.

[0128] FIG. 11 is a flowchart of a cell operation according to one embodiment of the present disclosure.

[0129] In step 1105, the cell can broadcast TDD downlink and TDD uplink frequency information.

[0130] In step 1110, the cell can perform an RRC establishment operation with the terminal to switch the terminal to a connection mode state.

[0131] In step 1115, when the cell performs operations such as measurement gap, SMTC, RMTC, DRX, etc., it may instruct the terminal to a predetermined cell that will serve as a reference point for SFN or subframe timing.

[0132] In step 1120, the cell can determine a necessary point in time (or reference point) for performing certain operations by taking into account the SFN or subframe timing of the set cell.

[0133] In step 1125, the cell can set a new Event-triggered cell measurement operation for the terminal.

[0134] In step 1130, the cell can receive a MeasurementReport message triggered by satisfying a new event from the terminal.

[0135] In step 1135, the cell can transmit to the terminal setting information for RLM / RLF operations to be performed in a predetermined set serving cell or all serving cells.

[0136] In step 1140, the cell receives a report from the terminal that there is a problem with the connection of the serving cell performing the role of the PCell.

[0137] In step 1145, the cell may transmit a specific RRC message or L1 / L2 signaling instructing the terminal to switch the PCell role to a specific serving cell having a good wireless link state.

[0138] In step 1150, the cell can transmit dormant BWP configuration information to the terminal for all serving cells.

[0139] In step 1155, the cell may not apply the dormant BWP setting information that is pre-configured in the serving cell instructed to perform the role of PCell.

[0140] In step 1160, the cell may receive a message from the terminal requesting the replacement of the serving cell acting as the PCell due to a specific cause (such as RLF or beam failure occurring in the serving cell acting as the PCell).

[0141] In step 1165, the cell can assign (set) the role of PCell to a predetermined serving cell in accordance with the terminal request.

[0142] In step 1170, the cell may transmit a PDCCH order containing an indicator that directs the terminal to a specific serving cell.

[0143] In step 1175, the cell can receive a preamble from the terminal.

[0144] In step 1180, the cell can send a RAR message to the terminal.

[0145] In step 1185, the cell can receive a msg3 message from the terminal.

[0146] In step 1190, the cell can send a msg4 message to the terminal.

[0147] FIG. 12 is a structure of a terminal according to one embodiment of the present disclosure.

[0148] Referring to FIG. 12, the terminal includes an RF (Radio Frequency) processing unit (1210), a baseband processing unit (1220), a storage unit (1230), and a control unit (1240).

[0149] The RF processing unit (1210) performs functions for transmitting and receiving signals through a wireless channel, such as signal band conversion and amplification. For example, the RF processing unit (1210) up-converts a baseband signal provided by the baseband processing unit (1220) into an RF band signal and transmits it through an antenna, and down-converts an RF band signal received through the antenna into a baseband signal. For example, the RF processing unit (1210) may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC (digital to analog converter), an ADC (analog to digital converter), etc. Of course, the components of the RF processing unit (1210) described above are merely examples, and the RF processing unit (1210) may include other components or omit some of the components described above. Although only one antenna is shown in the drawing, the terminal may be equipped with multiple antennas. Additionally, the RF processing unit (1210) may include a plurality of RF chains. Furthermore, the RF processing unit (1210) may perform beamforming. For beamforming, the RF processing unit (1210) may adjust the phase and magnitude of each of the signals transmitted and received through a plurality of antennas or antenna elements. Additionally, the RF processing unit may perform MIMO and may receive multiple layers when performing MIMO operation.

[0150] The baseband processing unit (1220) performs a conversion function between a baseband signal and a bit sequence according to the physical layer specifications of the system. For example, when transmitting data, the baseband processing unit (1220) generates complex symbols by encoding and modulating the transmitted bit sequence. Additionally, when receiving data, the baseband processing unit (1220) restores the received bit sequence by demodulating and decoding the baseband signal provided by the RF processing unit (1210). For example, in the case of following the OFDM (orthogonal frequency division multiplexing) method, when transmitting data, the baseband processing unit (1220) generates complex symbols by encoding and modulating the transmitted bit sequence, maps the complex symbols to subcarriers, and then constructs OFDM symbols through IFFT (inverse fast Fourier transform) operation and CP (cyclic prefix) insertion. Additionally, upon receiving data, the baseband processing unit (1220) divides the baseband signal provided by the RF processing unit (1210) into OFDM symbol units, restores the signals mapped to subcarriers through a fast Fourier transform (FFT) operation, and then restores the received bit sequence through demodulation and decoding.

[0151] The baseband processing unit (1220) and the RF processing unit (1210) transmit and receive signals as described above. Accordingly, the baseband processing unit (1220) and the RF processing unit (1210) may be referred to as a transmitting unit, a receiving unit, a transmitting and receiving unit, or a communication unit. Furthermore, at least one of the baseband processing unit (1220) and the RF processing unit (1210) may include a plurality of communication modules to support a plurality of different wireless access technologies. In addition, at least one of the baseband processing unit (1220) and the RF processing unit (1210) may include different communication modules to process signals of different frequency bands. For example, the different wireless access technologies may include wireless LAN (e.g., IEEE 802.11), cellular network (e.g., LTE), etc. In addition, the different frequency bands may include super high frequency (SHF) bands (e.g., 2.NRHz, NRHz) and millimeter wave (e.g., 60GHz) bands. The terminal may transmit and / or receive signals with a base station using a baseband processing unit (1220) and an RF processing unit (1210), and the signals may include control information and data.

[0152] The storage unit (1230) stores data such as basic programs, application programs, and setting information for the operation of the terminal. In particular, the storage unit (1230) can store information related to a second connection node that performs wireless communication using a second wireless connection technology. Additionally, the storage unit (1230) provides the stored data upon a request from the control unit (1240). The storage unit (1230) may be composed of a storage medium or a combination of storage media such as ROM, RAM, hard disk, CD-ROM, and DVD. Furthermore, the storage unit (1230) may be composed of multiple memories.

[0153] The control unit (1240) controls the overall operations of the terminal. For example, the control unit (1240) transmits and receives signals through the baseband processing unit (1220) and the RF processing unit (1210). Additionally, the control unit (1240) writes and reads data to and from the storage unit (1240). To this end, the control unit (1240) may include at least one processor. For example, the control unit (1240) may include a communication processor (CP) that performs control for communication and an application processor (AP) that controls upper layers such as applications. Additionally, at least one component within the terminal may be implemented as a single chip. Furthermore, according to one embodiment of the present disclosure, the control unit (1240) may include a multi-connection processing unit (1242) configured to process a process operating in a multi-connection mode.

[0154] FIG. 13 illustrates the block configuration of a base station in a wireless communication system according to one embodiment of the present disclosure.

[0155] As illustrated in the drawing above, the base station is configured to include an RF processing unit (1310), a baseband processing unit (1320), a backhaul communication unit (1330), a storage unit (1340), and a control unit (1350).

[0156] The RF processing unit (1310) performs functions for transmitting and receiving signals through a wireless channel, such as signal band conversion and amplification. For example, the RF processing unit (1310) upconverts a baseband signal provided by the baseband processing unit (1320) into an RF band signal and transmits it through an antenna, and downconverts an RF band signal received through the antenna into a baseband signal. For example, the RF processing unit (1310) may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, etc. Although only one antenna is shown in the drawing, the first connection node or base station may be equipped with multiple antennas. Additionally, the RF processing unit (1310) may include multiple RF chains. Furthermore, the RF processing unit (1310) may perform beamforming. For the above beamforming, the RF processing unit (1310) can adjust the phase and magnitude of each of the signals transmitted and received through a plurality of antennas or antenna elements. The RF processing unit can perform down-to-down MIMO operation by transmitting one or more layers.

[0157] The baseband processing unit (1320) performs a conversion function between a baseband signal and a bit sequence according to the physical layer specifications of the first wireless access technology. For example, when transmitting data, the baseband processing unit (1320) generates complex symbols by encoding and modulating the transmitted bit sequence. Additionally, when receiving data, the baseband processing unit (1320) restores the received bit sequence by demodulating and decoding the baseband signal provided by the RF processing unit (1310). For example, in the case of following the OFDM method, when transmitting data, the baseband processing unit (1320) generates complex symbols by encoding and modulating the transmitted bit sequence, maps the complex symbols to subcarriers, and then constructs OFDM symbols through IFFT operation and CP insertion. Additionally, upon receiving data, the baseband processing unit (1320) divides the baseband signal provided by the RF processing unit (1310) into OFDM symbol units, restores the signals mapped to subcarriers through FFT operations, and then restores the received bit sequence through demodulation and decoding. The baseband processing unit (1320) and the RF processing unit (1310) transmit and receive signals as described above. Accordingly, the baseband processing unit (1320) and the RF processing unit (1310) may be referred to as a transmitting unit, a receiving unit, a transceiver unit, a communication unit, or a wireless communication unit. A base station may transmit and / or receive signals with a terminal using the baseband processing unit (1320) and the RF processing unit (1310), and the signals may include control information and data.

[0158] The backhaul communication unit (1330) provides an interface for communicating with other nodes within the network. For example, the backhaul communication unit (1330) converts a bit sequence transmitted from the main base station to another node, such as an auxiliary base station or a core network, into a physical signal, and converts a physical signal received from the other node into a bit sequence. The backhaul communication unit (1330) may be included in the communication unit.

[0159] The storage unit (1340) stores data such as basic programs, application programs, and configuration information for the operation of the main station. In particular, the storage unit (1340) can store information regarding bearers assigned to connected terminals, measurement results reported from connected terminals, etc. Additionally, the storage unit (1340) can store information that serves as a criterion for determining whether to provide or disconnect multiple connections to the terminals. Furthermore, the storage unit (1340) provides the stored data in response to a request from the control unit (1350). The storage unit (1340) may be composed of a storage medium or a combination of storage media such as ROM, RAM, hard disk, CD-ROM, and DVD. Additionally, the storage unit (1340) may be composed of multiple memories.

[0160] The control unit (1350) controls the overall operations of the main base station. For example, the control unit (1350) transmits and receives signals through the baseband processing unit (1320) and the RF processing unit (1310) or through the backhaul communication unit (1330). Additionally, the control unit (1350) writes and reads data to and from the storage unit (1340). To this end, the control unit (1350) may include at least one processor. Additionally, at least one component of the base station may be implemented as a single chip. Furthermore, according to one embodiment of the present disclosure, the control unit (1350) may include a multiple connection processing unit (1352) configured to process a process operating in a multiple connection mode.

[0161] Methods according to the embodiments described in the claims or specification of the present disclosure may be implemented in the form of hardware, software, or a combination of hardware and software.

[0162] When implemented in software, a computer-readable storage medium may be provided for storing one or more programs (software modules). One or more programs stored in the computer-readable storage medium are configured for execution by one or more processors within an electronic device. 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 this disclosure.

[0163] These programs (software modules, software) may be stored in random access memory, non-volatile memory including flash memory, ROM (Read Only Memory), EEPROM (Electrically Erasable Programmable Read Only Memory), magnetic disc storage devices, CD-ROM (Compact Disc-ROM), Digital Versatile Discs (DVDs), or other forms of optical storage devices, magnetic cassettes. Alternatively, they may be stored in memory composed of some or all of these. Additionally, each constituent memory may include multiple units.

[0164] Additionally, the program may be stored on an attachable storage device accessible via a communication network such as the Internet, Intranet, Local Area Network (LAN), Wide LAN (WLAN), or Storage Area Network (SAN), or a combination thereof. Such a storage device may be connected to the device performing the embodiment of the present disclosure through an external port. Additionally, a separate storage device on the communication network may be connected to the device performing the embodiment of the present disclosure.

[0165] In the specific embodiments of the present disclosure described above, the components included in the disclosure are expressed in a singular or plural form according to the specific embodiments presented. However, the singular or plural expression is selected to suit the situation presented for convenience of explanation, and the present disclosure is not limited to singular or plural components; even if a component is expressed in the plural form, it may be composed of a singular form, or even if a component is expressed in the singular form, it may be composed of a plural form.

[0166] Meanwhile, although specific embodiments have been described in the detailed description of this disclosure, it is understood that various modifications are possible within the scope of this disclosure. Therefore, the scope of this disclosure should not be limited to the described embodiments, but should be defined by the claims set forth below as well as equivalents thereof. In other words, it is obvious to those skilled in the art that other modifications based on the technical concept of this disclosure are possible. Furthermore, each embodiment may be combined and operated as needed. For example, parts of the methods proposed in this disclosure may be combined to operate a base station and a terminal. Additionally, while the embodiments are presented based on 5G and NR systems, other modifications based on the technical concept of the embodiments may be implemented in other systems such as LTE, LTE-A, and LTE-A-Pro systems.

Claims

1. A method performed by a terminal in a wireless communication system, A step of receiving system information from a base station, including TDD frequency information including a TDD (time division duplex) uplink and a TDD downlink; A step of receiving configuration information regarding cell measurement on a radio resource identified based on the TDD frequency information from the base station of the RRC (radio resource control) connected serving cell; and The method includes the step of transmitting a measurement report regarding the serving cell to the base station based on the setting information, and A method wherein the serving cell comprises a reference cell, and the reference cell comprises a SpCell (special cell) and other serving cells excluding the SpCell.

2. In Paragraph 1, The setting information regarding the cell measurement above includes event conditions for triggering the measurement report, and A method comprising at least one of the above event conditions, wherein the above event condition includes a first event indicating that the size of the offset of a neighbor cell is greater than the signal strength of the serving cell, or a second event indicating that the signal strength of the serving cell is less than a first threshold and the signal strength of the neighbor cell is greater than a second threshold.

3. In paragraph 1, the above method is: A method further comprising the step of transmitting a message requesting a change to the cell where the RLF occurred to the base station when a radio link failure (RLF) occurs on a serving cell corresponding to the reference cell.

4. In paragraph 1, the above method is: A step of receiving configuration information regarding a dormant BWP (bandwidth part) from the base station; and A method further comprising the step of setting the above dormant BWP for the serving cell corresponding to the above reference cell.

5. In a method performed by a base station in a wireless communication system, A step of transmitting system information including TDD frequency information including TDD (time division duplex) uplink and TDD downlink to a terminal; A step of transmitting configuration information regarding cell measurement on a radio resource identified based on the TDD frequency information to the above terminal, wherein the terminal is connected via RRC (radio resource control) to a serving cell of the base station; and The method includes the step of receiving a measurement report regarding the serving cell from the terminal based on the setting information, A method wherein the serving cell comprises a reference cell, and the reference cell comprises a SpCell (special cell) and other serving cells excluding the SpCell.

6. In Paragraph 5, The setting information regarding the cell measurement above includes event conditions for triggering the measurement report, and A method comprising at least one of the above event conditions, wherein the above event condition includes a first event indicating that the size of the offset of a neighbor cell is greater than the signal strength of the serving cell, or a second event indicating that the signal strength of the serving cell is less than a first threshold and the signal strength of the neighbor cell is greater than a second threshold.

7. In paragraph 5, the above method is: A method further comprising the step of receiving a message from the terminal requesting a change to the cell where the RLF occurred when a radio link failure (RLF) occurs on a serving cell corresponding to the reference cell.

8. In paragraph 5, the above method is: The method further includes the step of transmitting configuration information regarding a dormant BWP (bandwidth part) to the above terminal, and A method in which the above dormant BWP is set in the serving cell corresponding to the above reference cell.

9. Regarding the terminal: At least one transceiver; At least one processor communicatively coupled to the above at least one transceiver; and It includes at least one memory that is communicationally coupled to the above at least one processor and stores instructions, and The above instructions are executed individually or in any combination by the above at least one processor, so that the terminal: Receive system information from a base station that includes TDD (time division duplex) uplink and TDD downlink, and From the base station of the RRC (radio resource control) connected serving cell, configuration information regarding cell measurement on a radio resource identified based on the TDD frequency information is received, and The above base station transmits a measurement report regarding the serving cell based on the above setting information, and A terminal in which the above serving cell includes a reference cell, and the above reference cell includes a SpCell (special cell) and other serving cells excluding the SpCell.

10. In Paragraph 9, The setting information regarding the cell measurement above includes event conditions for triggering the measurement report, and A terminal, wherein the above event condition includes at least one of a first event indicating that the size of the offset of a neighbor cell is greater than the signal strength of the serving cell, or a second event indicating that the signal strength of the serving cell is less than a first threshold and the signal strength of the neighbor cell is greater than a second threshold.

11. In paragraph 9, the above commands are the terminal: A terminal that, when a radio link failure (RLF) occurs on a serving cell corresponding to the reference cell, transmits a message requesting a change to the cell where the RLF occurred to the base station.

12. In paragraph 9, the above commands are the terminal: Receive configuration information regarding a dormant BWP (bandwidth part) from the above base station, and A terminal that sets the above dormant BWP for the serving cell corresponding to the above reference cell.

13. Regarding base stations: At least one transceiver; At least one processor communicatively coupled to the above at least one transceiver; and It includes at least one memory that is communicationally coupled to the above at least one processor and stores instructions, and The above instructions are executed individually or in any combination by the above at least one processor, so that the base station: Transmit system information including TDD frequency information including TDD (time division duplex) uplink and TDD downlink to a terminal, and The above terminal transmits configuration information regarding cell measurement on a radio resource identified based on the TDD frequency information, the terminal is connected via RRC (radio resource control) to the serving cell of the base station, and From the above terminal, a measurement report regarding the serving cell is received based on the above setting information, and A base station in which the above serving cell includes a reference cell, and the above reference cell includes a SpCell (special cell) and other serving cells excluding the SpCell.

14. In Paragraph 13, The setting information regarding the cell measurement above includes event conditions for triggering the measurement report, and A base station, wherein the above event condition includes at least one of a first event indicating that the size of the offset of a neighbor cell is greater than the signal strength of the serving cell, or a second event indicating that the signal strength of the serving cell is less than a first threshold and the signal strength of the neighbor cell is greater than a second threshold.

15. In Paragraph 13, the above commands are the base station: A base station that receives a message from the terminal requesting a change to the cell where the RLF occurred when a radio link failure (RLF) occurs on a serving cell corresponding to the reference cell.

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