Method and apparatus for performing conditional switching in wireless communication system

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. A method performed by a user equipment (UE) in a wireless communication system, the method comprising: receiving a measurement configuration from a source master node (S-MN), the measurement configuration comprising a first condition for conditional handover (CHO) and a second condition for conditional primary-secondary cell group cell (PSCell) to change CPC; and executing the CHO to the target primary node T-MN and executing the CPC to the target secondary node T-SN under the condition that the first condition and the second condition are both met.

Description

Technical Field

[0001] The present disclosure relates to operations of a terminal in a wireless communication system. In particular, the present disclosure relates to a method and apparatus for applying a specific secondary cell group configuration when performing a handover to a specific primary cell in a wireless communication system. Background Art

[0002] 5G mobile communication technology defines a wide frequency band so that high transmission rates and new services are possible, and can be implemented not only in "below 6 GHz" frequency bands such as 3.5 GHz, but also in "above 6 GHz" frequency bands called millimeter waves including 28 GHz and 39 GHz. In addition, implementation of 6G mobile communication technology (referred to as a super 5G system) in a terahertz (THz) frequency band (e.g., 95 GHz to 3 THz frequency band) has been considered in order to achieve a transmission rate fifty times faster than that of 5G mobile communication technology and an ultra-low latency that is one-tenth of that of 5G mobile communication technology.

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

[0004] Currently, with respect to services supported by 5G mobile communication technology, the industry is continuously discussing improvements and performance enhancements on initial 5G mobile communication technology, and has completed physical layer standardization on technologies such as: V2X (Vehicle-to-Everything) for assisting driving decisions of autonomous vehicles based on information about the location and status of vehicles sent by vehicles and for improving user convenience, NR-U (New Radio Unlicensed) for system operations that comply with various regulatory-related requirements in unlicensed frequency bands, NR UE energy saving, non-terrestrial network (NTN) for UE satellite direct communication for ensuring coverage in areas where communication with terrestrial networks is not possible, and positioning.

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

[0006] As 5G mobile communication systems are commercialized, the exponentially growing number of connected devices will be connected to the communication network, and therefore it is expected that enhanced functions and performance of 5G mobile communication systems and integrated operations of connected devices will be required. To this end, new research on the following technologies is on the agenda: extended reality (XR) for efficient support of AR (augmented reality), VR (virtual reality), MR (mixed reality), etc., 5G performance improvement and complexity reduction by utilizing artificial intelligence (AI) and machine learning (ML), AI service support, metaverse service support, and drone communication.

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

[0008] As described above, as wireless communication systems continue to develop to provide various services, methods for smoothly providing services are needed. In particular, a technology for controlling reference signals to reduce energy consumption of base stations in wireless communication systems is needed.

[0009] The above information is provided as background information only to assist with understanding the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above information may be prior art with respect to the present disclosure.

[0010] With the development of wireless communication systems as described above, various services can be provided, and thus a scheme for efficiently providing these services is required.

[0011] The above information is provided as background information only to assist with understanding the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above information may be prior art with respect to the present disclosure. Summary of the invention

[0012] Solution to the problem

[0013] The present invention relates to a wireless communication network, and in particular to a terminal in a wireless communication system and a communication method thereof.

[0014] According to aspects of the present invention, an operation method of a terminal in a wireless communication system includes: receiving a signal from a source master node, the signal including information about a first condition, information about a second condition, and conditional switching (CHO) configuration information corresponding to each of the conditions; based on the received signal, determining whether at least one of the first condition and the second condition is satisfied; based on the determined result, applying CHO configuration information corresponding to the condition satisfied between the first condition and the second condition; and performing random access to a target master node based on the applied CHO configuration information.

[0015] Beneficial Effects

[0016] An aspect of the present disclosure is to address at least the above problems and / or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the present invention is to provide an efficient communication method in a wireless communication system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and other aspects, features and advantages of certain embodiments of the present disclosure will become more apparent from the following description taken in conjunction with the accompanying drawings, in which: Figure 1 The structure of an LTE system related to an embodiment of the present disclosure is shown; Figure 2 A radio protocol structure of an LTE system related to an embodiment of the present disclosure is shown; Figure 3 The structure of a next generation mobile communication system according to an embodiment of the present disclosure is shown; Figure 4 A radio protocol structure of a next generation mobile communication system according to an embodiment of the present disclosure is shown; Figure 5Showing the structure of a terminal according to an embodiment of the present disclosure; Figure 6 The structure of a base station according to an embodiment of the present disclosure is shown; Fig. 7A illustrates CHO operations associated with embodiments of the present disclosure; Figure 7B shows the structure of CHO configuration information related to an embodiment of the present disclosure; Fig. 8A An operation of performing CHO when both a Type 1 condition and a Type 2 condition are satisfied according to an embodiment of the present disclosure is illustrated, wherein the T-MN determines the Type 2 condition; Figure 8B shows the structure of CHO configuration information according to an embodiment of the present disclosure; Fig.9A illustrates an operation of performing CHO when both Type 1 conditions and Type 2 conditions are satisfied according to an embodiment of the present disclosure, wherein the T-SN determines the Type 2 condition; Fig. 9B shows the structure of CHO configuration information according to an embodiment of the present disclosure; Fig. 10A It is shown that according to an embodiment of the present disclosure, it is determined whether each of the type 1 condition and the type 2 condition is satisfied, and an operation of performing CHO is performed when the SCG is applied hierarchically, wherein the T-MN determines the type 2 condition; Fig. 10B shows the structure of CHO configuration information according to an embodiment of the present disclosure; Fig.11A An operation of determining whether each of the type 1 condition and the type 2 condition is satisfied and performing CHO when the SCG is applied hierarchically is shown according to an embodiment of the present disclosure, wherein the T-SN determines the type 2 condition; and Fig. 11B The structure of CHO configuration information according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0018] Best Mode for Carrying Out the Invention

[0019] An aspect of the present disclosure is to address at least the above problems and / or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the present invention is to provide a terminal in a wireless communication system and a communication method thereof.

[0020] According to an embodiment of the present disclosure, an operation method of a terminal in a wireless communication system includes: receiving a signal from a source master node, the signal including information about a first condition, information about a second condition, and conditional switching (CHO) configuration information corresponding to each of the conditions; based on the received signal, determining whether at least one of the first condition and the second condition is satisfied; based on the determined result, applying CHO configuration information corresponding to the condition satisfied between the first condition and the second condition; and performing random access to a target master node based on the applied CHO configuration information.

[0021] Various embodiments of the present disclosure provide an apparatus and method for efficiently providing a service in a wireless communication system.

[0022] Effects obtainable from the present disclosure are not limited to the above-mentioned effects, and other unmentioned effects can be clearly understood by those skilled in the art to which the present disclosure pertains through the following description.

[0023] Before proceeding to the following detailed description, it may be helpful to set forth definitions of certain words and phrases used in this patent document: the terms "include" and "comprising" and their derivatives mean including but not limited to; the term "or" is inclusive, meaning and / or; the phrases "associated with" and "associated with" and their derivatives may mean including, included, interconnected with, containing, contained within, connected to or connected with, coupled to or coupled with, communicable with, cooperating with, interleaved, juxtaposed, adjacent, bound to or bound with, having, having the property of, etc.; and the term "controller" means any device, system, or part thereof that controls at least one operation, such device may be implemented in hardware, firmware, or software, or a combination of at least two thereof. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether locally or remotely.

[0024] In addition, the various functions described below can be implemented or supported by one or more computer programs, each of which is formed by a computer-readable program code and is contained in a computer-readable medium. The terms "application" and "program" refer to one or more computer programs, software components, instruction sets, processes, functions, objects, classes, instances, related data, or parts thereof suitable for implementation in appropriate computer-readable program codes. The phrase "computer-readable program code" includes any type of computer code, including source code, object code, and executable code. The phrase "computer-readable medium" includes any type of medium that can be accessed by a computer, such as a read-only memory (ROM), a random access memory (RAM), a hard drive, a compact disk (CD), a digital video disk (DVD), or any other type of memory. "Non-transitory" computer-readable media do not include wired communication links, wireless communication links, optical communication links, or other communication links that transmit temporary electrical signals or other signals. Non-transitory computer-readable media include media in which data can be permanently stored and media in which data can be stored and subsequently overwritten, such as rewritable optical disks or erasable storage devices.

[0025] Definitions for certain words and phrases are provided throughout this patent document, those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases.

[0026] Embodiments of the present invention

[0027] Discussed below Figures 1 to 11B The various embodiments used to describe the principles of the present disclosure in this patent document are merely exemplary and should not be interpreted in any way as limiting the scope of the present disclosure. Those skilled in the art should understand that the principles of the present disclosure can be implemented in any appropriately arranged system or device.

[0028] Hereinafter, the working principle of the present disclosure will be described with reference to the accompanying drawings. In the following description of the present disclosure, when it is determined that the subject matter of the present disclosure will be unnecessarily unclear, a detailed description of a well-known function or configuration may be omitted. The terms to be described below are defined in consideration of the functions in the present disclosure and may differ depending on the user, the user's intention or habit. Therefore, these terms should be defined based on the content of the entire specification.

[0029] In the following description, for the sake of convenience, terms used to identify access nodes, terms related to network entities, terms related to messages, terms related to interfaces between network entities, terms related to various identification information, etc. are exemplarily used. Therefore, the present disclosure is not limited to the terms used below, and other terms related to subjects with equivalent technical meanings may be used.

[0030] In the following description, a base station is an entity that allocates resources to a terminal, and may be at least one of a gNode B, an eNode B, a Node B, a base station (BS), a wireless access unit, a base station controller, and a node on a network. The terminal may include a user equipment (UE), a mobile station (MS), a cellular phone, a smart phone, a computer, or a multimedia system capable of performing a communication function. Of course, examples of base stations and terminals are not limited thereto. In the present disclosure, "downlink (DL)" refers to a radio link via which a base station sends a signal to a terminal, and "uplink (UL)" refers to a radio link via which a terminal sends a signal to a base station. In addition, in the following description, an LTE or LTE-A system may be described by way of example, but the embodiments of the present disclosure may also be applied to other communication systems having similar technical backgrounds or channel types. Examples of such communication systems may include fifth-generation mobile communication technologies (5G, new radio, and NR) developed on top of LTE-A, and in the following description, "5G" may be a concept covering existing LTE, LTE-A, or other similar services. In addition, based on the judgment of those skilled in the art, the embodiments of the present disclosure may also be applied to other communication systems with some modifications without significantly departing from the scope of the present disclosure. It will be understood herein that each block of the flowchart and combinations of blocks in the flowchart can be implemented by computer program instructions.

[0031] These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device to produce a machine so that the instructions executed by the processor of the computer or other programmable data processing device formulate means for implementing the functions specified in one or more flowchart boxes. These computer program instructions can also be stored in a computer-usable or computer-readable memory, which can instruct the computer or other programmable data processing device to operate in a specific manner so that the instructions stored in the computer-usable or computer-readable memory produce a product including instruction means for implementing the functions specified in one or more flowchart boxes. The computer program instructions can be loaded onto a computer or other programmable data processing device to trigger a series of operational steps to be executed on a computer or other programmable device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable device can provide steps for implementing the functions specified in one or more flowchart boxes.

[0032] In addition, each box in the flowchart may represent a module, segment or part of a code including one or more executable instructions for implementing a specified logical function. In addition, it should also be noted that in some alternative implementations, the functions mentioned in the box may not occur in order. For example, two boxes shown in succession may actually be executed substantially simultaneously, or the boxes may sometimes be executed in reverse order, depending on the functions involved. As used in the embodiments of the present disclosure, "unit" refers to a software element or hardware element that plays a certain role, such as a field programmable gate array (FPGA) or an application-specific integrated circuit (ASIC). However, "unit" is not limited to the definition of software or hardware. "Unit" can be constructed to be stored in an addressable storage medium or executed by one or more processors. Therefore, "unit" includes, for example: software elements, object-oriented software elements, class elements and task elements, processes, functions, attributes, procedures, subroutines, program code segments, drivers, firmware, microcodes, circuits, data, databases, data architectures, tables, arrays and parameters. The elements and functions provided by the "unit" can be combined into fewer elements or "units", or can be divided into more elements or "units". Furthermore, the elements and "units" may be implemented as one or more CPUs within a device or a secure multimedia card. Furthermore, the "units" in the embodiments may include one or more processors.

[0033] The following description of the embodiments of the present disclosure is mainly directed to a packet core 5G system or a 5G core network or a next generation core (NG core) as a new radio (NR) as a radio access network and as a core network in the 5G mobile communication standard specified by the Third Generation Partnership Project (3GPP) as a mobile communication standardization organization, but based on the judgment of those skilled in the art, the main ideas of the present disclosure can be applied to other communication systems with similar backgrounds through some modifications without significantly departing from the scope of the present disclosure. In the following description of the present disclosure, for ease of description, terms and names defined in the 3GPP standard (a standard for 5G, NR, LTE or similar systems) in the existing communication standards may be used. However, the present disclosure is not limited to these terms and names, and can be applied to systems that comply with other standards in the same manner. In particular, the present disclosure can be applied to 3GPP 5Gs / NR (fifth generation mobile communication standard).

[0034] In addition, the present disclosure can be applied to smart services based on 5G communication technology and IoT-related technology (e.g., smart homes, smart buildings, smart cities, smart vehicles or connected vehicles, healthcare, digital education, retail business, security and safety-related services, etc.). In the present disclosure, the term "eNB" and the term "gNB" can be used interchangeably. That is, a base station described as an "eNB" can indicate a "gNB". In addition, the term "terminal" can refer not only to mobile phones, NB-IoT devices, and sensors, but also to other wireless communication devices.

[0035] Wireless communication systems are developing towards broadband wireless communication systems for providing high-speed and high-quality packet data services using communication standards as well as typical voice-based services. The communication standards are, for example, 3GPP's High Speed ​​Packet Access (HSPA), LTE (Long Term Evolution or Evolved Universal Terrestrial Radio Access (E-UTRA)), LTE-Advanced (LTE-Advanced, LTE-A), LTE-Pro (Enhanced LTE), 3GPP2's High Rate Packet Data (HRPD), Ultra Mobile Broadband (UMB), IEEE 802.16e, etc.

[0036] As a typical example of a broadband wireless communication system, the LTE system adopts an orthogonal frequency division multiplexing (OFDM) scheme in the downlink (DL) and a single carrier frequency division multiple access (SC-FDMA) scheme in the uplink (UL). The uplink indicates a radio link through which a user equipment (UE) (or a mobile station (MS)) transmits data or a control signal to a base station (BS) (eNode B), and the downlink indicates a radio link through which a base station transmits data or a control signal to a UE. The above-mentioned multiple access scheme separates the data or control information of each user by allocating and operating time-frequency resources for transmitting data or control information to each user to avoid mutual overlap, that is, to establish orthogonality.

[0037] Since the 5G communication system, which is a post-LTE communication system, can freely reflect the various needs of users, service providers, etc., it can support services that meet various needs. Services considered in the 5G communication system include enhanced mobile broadband (eMBB) communication, massive machine type communication (mMTC), ultra-reliable low latency communication (URLLC), etc.

[0038] According to some embodiments, eMBB is intended to provide a higher data rate than that supported by existing LTE, LTE-A or LTE-Pro. For example, in a 5G communication system, eMBB can provide a peak data rate of 20Gbps in the downlink for a single base station and a peak data rate of 10Gbps in the uplink. In addition, the 5G communication system can provide an improved user-perceived data rate and a maximum data rate to the UE. In order to meet this requirement, it is necessary to improve the transmission / reception technology including further enhanced multiple-input multiple-output (MIMO) transmission technology. In addition, the data rate required by the 5G communication system can be obtained using a frequency bandwidth greater than 20MHz in a frequency band of 3GHz to 6GHz or 6GHz or higher, rather than using a maximum transmission bandwidth of 20MHz to send signals in the 2GHz frequency band used in LTE.

[0039] In addition, mMTC is being considered for supporting application services such as the Internet of Things (IoT) in 5G communication systems. In order to efficiently provide the Internet of Things, mMTC has requirements such as supporting the connection of a large number of UEs within a cell, enhancing the coverage of UEs, improving battery time, and reducing the cost of UEs. Since the Internet of Things provides communication functions while being provided to various sensors and various equipment, the Internet of Things can support a large number of UEs within a cell (e.g., 1 million UEs / km2). In addition, UEs supporting mMTC may require wider coverage than those UEs for other services provided by the 5G communication system, because given the characteristics of the service, the UE is likely to be located in a shadow area that is not covered by the cell, such as the basement of a building. UEs supporting mMTC can be configured to be low-cost and may require a very long battery life of, for example, 10 to 15 years, because it is difficult to frequently replace the battery of the UE.

[0040] Finally, URLLC is a cellular-based mission-critical wireless communication service that can be used for remote control of robots or machines, industrial automation, drones, remote healthcare, emergency alerts, etc. Therefore, URLLC can provide ultra-low latency and ultra-high reliable communications. For example, services supporting URLLC can meet an air interface delay of less than 0.5ms and also require a packet error rate of 10-5 or less. Therefore, for services supporting URLLC, the 5G system can provide a shorter transmission time interval (TTI) than that of other services, and may also require a design for allocating a large amount of resources in the frequency band to ensure the reliability of the communication link.

[0041] The above three services considered in the 5G communication system, i.e., eMBB, URLLC, and mMTC, can be multiplexed and transmitted in a single system. In order to meet the different needs of each service, different transmission / reception technologies and transmission / reception parameters can be used between services. However, the above mMTC, URLLC<, and eMBB are only examples of different types of services, and the service types applied by the present disclosure are not limited to the above examples.

[0042] Hereinafter, the present disclosure provides an apparatus and method for performing handover in a wireless communication system. More specifically, various embodiments of the present disclosure provide an apparatus and method for performing conditional handover (CHO) in a wireless communication system. In various embodiments, CHO may refer to a terminal selecting a target cell from candidate cells that meet a CHO trigger condition and performing handover to the selected target cell.

[0043] In the present disclosure, a master node (MN) may be interpreted as a master base station, and a secondary node (SN) may be interpreted as a secondary base station. In addition, in an embodiment of the present disclosure, the MN and the SN may be different base stations or base stations using different radio access technologies (RATs), and in some cases, may be base stations using the same RAT. The MN and the SN may be distinguished by using general expressions such as a first base station and a second base station.

[0044] Figure 1 The structure of an LTE system related to an embodiment of the present disclosure is shown.

[0045] Reference Figure 1 As shown in the figure, the radio access network of the LTE system may include a next generation base station (evolved Node B, hereinafter referred to as eNB, Node B or base station) 1-05, 1-10, 1-15 or 1-20, a mobility management entity (MME) 1-25 and a serving gateway (S-GW) 1-30. User equipment (hereinafter referred to as UE or terminal) 1-35 may access an external network via eNB 1-05 to eNB 1-20 and S-GW 1-30.

[0046] exist Figure 1In the present invention, eNB 1-05 to eNB 1-20 may correspond to an existing Node B of a UMTS system. The eNB is connected to the UE 1-35 through a wireless channel and may perform a more complex role than an existing Node B. In an LTE system, all user services including real-time services over an Internet protocol such as Voice over IP (VoIP) may be served through a shared channel. Therefore, a device for performing scheduling by collecting status information such as a buffer status of a UE, an available transmission power status, and a channel status may be required, and eNB 1-05 to eNB 1-20 may be responsible for scheduling. One gNB may generally control multiple cells. For example, in order to achieve a transmission rate of 100 Mbps, an LTE system may use orthogonal frequency division multiplexing (OFDM) as a radio access technology in a 20 MHz bandwidth. The present disclosure is not limited to the above example. In addition, eNB 1-05 to eNB 1-20 may apply an adaptive modulation and coding (AMC) scheme to determine a modulation scheme and a channel coding rate according to a channel status of a terminal. The S-GW 1-30 is a device for providing a data bearer, and may generate or remove a data bearer according to the control of the MME 1-25. The MME is a device in charge of various control functions for a terminal and a mobility management function, and may be connected to a plurality of base stations.

[0047] Figure 2 A radio protocol structure of an LTE system related to an embodiment of the present disclosure is shown.

[0048] Reference Figure 2 , the radio protocol of the LTE system may include the packet data convergence protocol (PDCP) 2-05 and 2-40, the radio link control (RLC) 2-10 and 2-35, the medium access control (MAC) 2-15 and 2-30, and the physical (PHY) 2-20 and 2-25 layers in the terminal and the eNB respectively. The radio protocol of the LTE system may include Figure 2 More or fewer layers may be configured as shown.

[0049] According to an embodiment of the present disclosure, PDCP may be responsible for operations such as IP header compression / recovery. The main functions of PDCP may be summarized as follows. The present disclosure is not limited to the following examples.

[0050] - Header compression and decompression function (Header compression and decompression: ROHC only).

[0051] -User data transfer function (transmission of user data).

[0052] - In-sequence delivery function (for RLC AM, in-sequence delivery of upper layer PDUs during PDCP re-establishment process).

[0053] - Sequence reordering functionality (for offload bearers in DC (supports RLC AM only): PDCP PDU routing for transmission and PDCP PDU reordering for reception).

[0054] -Duplicate detection function (for RLC AM, duplicate detection of lower layer SDUs during PDCP re-establishment process).

[0055] - Retransmission functionality (retransmission of PDCP SDUs at handover for offloaded bearers in DC and retransmission of PDCP PDUs during PDCP data recovery for RLC AM).

[0056] - Encryption and decryption functions (encryption and decryption).

[0057] - Timer-based SDU discard functionality (Timer-based SDU discard in uplink).

[0058] According to an embodiment of the present disclosure, the radio link control (RLC) 2-10 and 2-35 can perform ARQ operation by reconfiguring the PDCP packet data unit (PDU) to an appropriate size. The main functions of the RLC can be summarized as follows. The present disclosure is not limited to the following embodiments.

[0059] -Data transmission function (transmission of upper layer PDU).

[0060] -ARQ functionality (error correction via ARQ (for AM data transmission only)).

[0061] - Concatenation, segmentation and reassembly function (concatenation, segmentation and reassembly of RLC SDU (only for UM and AM data transmission)).

[0062] - Re-segmentation function (resegmentation of RLC data PDU (only for AM data transmission)).

[0063] - Sequence reordering function (reordering of RLC data PDUs (only for UM and AM data transmission)).

[0064] - Duplicate detection function (Duplicate detection (for UM and AM data transmission only)).

[0065] - Error detection function (protocol error detection (for AM data transmission only)).

[0066] -RLC SDU discard function (RLC SDU discard (for UM and AM data transmission only)).

[0067] -RLC re-establishment function (RLC Re-establishment).

[0068] According to the embodiment, MAC 2-15 and 2-30 are connected to several RLC layer devices configured in one terminal, and can perform operations of multiplexing RLC PDU into MAC PDU and demultiplexing RLC PDU from MAC PDU. The main functions of MAC can be summarized as follows. The present disclosure is not limited to the following embodiments.

[0069] - Mapping function (mapping between logical channels and transport channels).

[0070] - Multiplexing and demultiplexing functions (multiplexing MAC SDUs belonging to one or different logical channels into transport blocks (TBs) delivered to the physical layer on transport channels, or demultiplexing MAC SDUs belonging to one or different logical channels from transport blocks (TBs) delivered from the physical layer on transport channels).

[0071] -Scheduling information reporting function (Scheduling information reporting).

[0072] -HARQ functionality (error correction through HARQ).

[0073] - Priority handling function between logical channels (priority handling between logical channels of a UE).

[0074] - Priority handling function between terminals (priority handling between UEs through dynamic scheduling).

[0075] -MBMS service identification function (MBMS Service Identification).

[0076] -Transmission format selection function (Transmission format selection).

[0077] - Fill function (fill).

[0078] According to an embodiment, the PHY layers 2-20 and 2-25 may perform an operation of channel encoding and modulating upper layer data into OFDM symbols to send the OFDM symbols via a wireless channel, or may perform an operation of demodulating and channel decoding OFDM symbols received via a wireless channel to pass the demodulated and channel-decoded OFDM symbols to an upper layer.

[0079] Figure 3 A structure of a next generation mobile communication system according to an embodiment of the present disclosure is shown.

[0080] Reference Figure 3, the radio access network of the next generation mobile communication system (hereinafter referred to as NR or 5G) may include a new radio node B (hereinafter referred to as NR gNB or NR base station) 3-10 and a new radio core network (NRCN) 3-05. The new radio user equipment (NR UE or terminal) 3-15 can access the external network via the NR gNB 3-10 and the NR CN 3-05.

[0081] exist Figure 3 In the present invention, the NR gNB 3-10 may correspond to the evolved Node B (eNB) of the existing LTE system. The NR gNB is connected to the NR UE 3-15 via a wireless channel and may provide services superior to the existing Node B. In the next generation mobile communication system, all user services may be served via a shared channel. Therefore, a device may be required for performing scheduling by collecting status information such as the buffer status, available transmission power status, and channel status of the UE, and the NR NB 3-10 may be responsible for scheduling. One NR gNB may control multiple cells. According to an embodiment of the present disclosure, in the next generation mobile communication system, a bandwidth larger than the conventional maximum bandwidth may be applied to achieve high-speed data transmission compared to general LTE.

[0082] In addition, according to an embodiment of the present disclosure, beamforming technology can be additionally applied as a radio access technology by using an OFDM scheme. In addition, an adaptive modulation and coding (hereinafter referred to as AMC) scheme for determining a modulation scheme and a channel coding rate according to the channel state of the terminal can be applied. NRCN 3-05 can perform functions such as mobility support, bearer configuration, and QoS configuration. NR CN is a device responsible for various control functions for terminals and mobility management functions, and can be connected to multiple base stations. In addition, the next generation mobile communication system can be linked to the LTE system, and the NR CN can be connected to the MME 3-25 via a network interface. The MME can be connected to the eNB 3-30 which is an LTE base station.

[0083] Figure 4 A radio protocol structure of a next generation mobile communication system according to an embodiment of the present disclosure is shown.

[0084] Reference Figure 4 , the radio protocol of the next generation mobile communication system may include NR Service Data Adaptation Protocol (SDAPS) 4-01 and 4-45, NR PDCP 4-05 and 4-40, NR RLC 4-10 and 4-35, NR MAC4-15 and 4-30, and NR PHY 4-20 and 4-25 layer devices in the terminal and NR base station respectively (hereinafter, layer and layer device may be used interchangeably). The radio protocol of the next generation mobile communication system may include more Figure 4 More or fewer layers may be configured as shown.

[0085] According to an embodiment of the present disclosure, the main functions of NR SDAPS 4-01 and 4-45 may include some of the following functions. The present disclosure is not limited to the following examples.

[0086] -User data transmission function (transmission of user plane data)

[0087] - Mapping functionality for QoS flows and data bearers for uplink and downlink (mapping between QoS flows and DRBs for DL ​​and UL).

[0088] - QoS Flow ID marking function for uplink and downlink (marking QoS Flow ID in both DL and UL packets).

[0089] - Functionality to map Reflective QoS flows to data bearers of uplink SDAP PDUs (Map Reflective QoS flows to DRBs of UL SDAPPDUs).

[0090] According to an embodiment of the present disclosure, for an SDAP layer device, information about whether to use a header of an SDAP layer device for each PDCP layer device, for each bearer, or for each logical channel, or whether to use a function of an SDAP layer device, can be configured for the terminal through a radio resource control (RRC) message. When configuring the SDAP header, a 1-bit non-access stratum (NAS) quality of service (QoS) reflection configuration indicator (NAS reflection QoS) and a 1-bit access stratum (AS) QoS reflection configuration indicator (AS reflection QoS) of the SDAP header can indicate that the terminal updates or reconfigures mapping information related to QoS flows and data bearers for uplink and downlink. The SDAP header may include QoS flow ID information indicating QoS. QoS information can be used as data processing priority, scheduling information, etc. to support seamless services.

[0091] According to an embodiment of the present disclosure, the main functions of NR PDCP 4-05 and 4-40 may include some of the following functions. The present disclosure is not limited to the following examples.

[0092] - Header compression and decompression function (Header compression and decompression: ROHC only).

[0093] -User data transfer function (transmission of user data).

[0094] - In-sequence delivery function (in-sequence delivery of upper layer PDUs).

[0095] - Out-of-order delivery function (out-of-order delivery of upper layer PDUs).

[0096] - Sequence reordering functionality (PDCP PDU reordering for reception).

[0097] - Duplicate detection function (duplicate detection of lower layer SDU).

[0098] - Retransmission functionality (retransmission of PDCP SDUs).

[0099] - Encryption and decryption functions (encryption and decryption).

[0100] - Timer-based SDU discard functionality (Timer-based SDU discard in uplink).

[0101] According to an embodiment of the present disclosure, a sequence reordering function (reordering) of an NR PDCP device may refer to a function of sequentially reordering PDCP PDUs received from a lower layer based on a PDCP sequence number (SN). The sequence reordering function (reordering) of the NR PDCP device may include a function of delivering data to an upper layer in a reordered sequence, or may include a function of directly delivering data without considering the sequence, may include a function of recording lost PDCP PDUs by reordering the sequence, may include a function of reporting the status of lost PDCP PDUs to a transmitting side, and may include a function of requesting retransmission of lost PDCP PDUs.

[0102] According to an embodiment of the present disclosure, the main functions of NR RLC 4-10 and 4-35 may include some of the following functions. The present disclosure is not limited to the following examples.

[0103] -Data transmission function (transmission of upper layer PDU).

[0104] - In-sequence delivery function (in-sequence delivery of upper layer PDUs).

[0105] - Out-of-order delivery function (out-of-order delivery of upper layer PDUs).

[0106] -ARQ functionality (error correction through ARQ).

[0107] - Concatenation, segmentation and reassembly function (concatenation, segmentation and reassembly of RLC SDU).

[0108] - Re-segmentation function (resegmentation of RLC data PDUs).

[0109] -Sequence reordering function (reordering of RLC data PDUs).

[0110] - Duplicate detection function (Duplicate Detection).

[0111] - Error detection function (protocol error detection).

[0112] -RLC SDU discard function (RLC SDU discard).

[0113] -RLC re-establishment function (RLC Re-establishment).

[0114] According to an embodiment of the present disclosure, the in-sequence delivery function of the NR RLC device may refer to a function of sequentially delivering the RLC SDUs received from the lower layer to the upper layer. The in-sequence delivery function of the NR RLC device may include the following functions: when the original RLC SDU is segmented into several RLC SDUs and received, the received RLC SDUs are reassembled and delivered.

[0115] According to an embodiment of the present disclosure, the in-sequence delivery function of the NR RLC device may include a function of reassembling the received RLC PDU based on the RLC sequence number (SN) or the PDCP sequence number (SN), may include a function of recording lost RLC PDUs by sequence reordering, may include a function of reporting the status of lost RLC PDUs to the transmitting side, and may include a function of requesting retransmission of lost RLC PDUs.

[0116] The in-sequence delivery function of the NR RLC device may include at least one of the following functions: when there is a lost RLC SDU, only the RLC SDU before the lost RLC SDU is delivered to the upper layer in sequence; even if there is a lost RLC SDU, if a predetermined timer has expired, all RLC SDUs received before the start of the timer are delivered to the upper layer in sequence; and even if there is a lost RLC SDU, if a predetermined timer has expired, all RLC SDUs received until the current one are delivered to the upper layer in sequence.

[0117] According to an embodiment of the present disclosure, the NR RLC device can process the RLC PDU in the order of reception and send the processed RLC PDU to the NR PDCP device regardless of the order of the sequence numbers (out-of-order delivery).

[0118] According to an embodiment of the present disclosure, when segments are received, the NR RLC device can receive segments stored in a buffer or to be received later, reconfigure the segments into a complete RLC PDU, and send the reconfigured segments to the NR PDCP device.

[0119] According to an embodiment of the present disclosure, the NR RLC layer may not include a cascading function, and may perform a function in the NR MAC layer or replace the function with a multiplexing function of the NR MAC layer.

[0120] According to an embodiment of the present disclosure, the out-of-order delivery function of the NR RLC device may refer to a function of directly delivering the RLC SDU received from the lower layer to the upper layer regardless of the sequence. The out-of-order delivery function of the NR RLC device may include the following functions: when the original RLC SDU is segmented into several RLC SDUs and is received, the received RLC SDU is reassembled and delivered. The out-of-order delivery function of the NR RLC device may include the following functions: storing the RLC SN or PDCP SN of the received RLC PDU and reordering the sequence to record the lost RLC PDU.

[0121] According to an embodiment of the present disclosure, NR MAC 4-15 and 4-30 can be connected to a plurality of NR RLC layer devices configured in one terminal, and the main functions of NR MAC may include some of the following functions. The present disclosure is not limited to the following examples.

[0122] - Mapping function (mapping between logical channels and transport channels).

[0123] -Multiplexing and demultiplexing functions (multiplexing / demultiplexing of MAC SDU).

[0124] -Scheduling information reporting function (Scheduling information reporting).

[0125] -HARQ functionality (error correction via HARQ).

[0126] - Priority handling function between logical channels (priority handling between logical channels of a UE).

[0127] - Priority handling function between terminals (priority handling between UEs through dynamic scheduling).

[0128] -MBMS service identification function (MBMS Service Identification).

[0129] -Transmission format selection function (Transmission format selection).

[0130] - Fill function (fill).

[0131] According to an embodiment of the present disclosure, the NR PHY layers 4-20 and 4-25 may perform an operation of channel encoding and modulating upper layer data into OFDM symbols to transmit the OFDM symbols via a wireless channel, or may perform an operation of demodulating and channel decoding OFDM symbols received via a wireless channel to deliver the demodulated and channel-decoded OFDM symbols to an upper layer. The present disclosure is not limited to the above examples.

[0132] Figure 5 The structure of a terminal according to an embodiment of the present disclosure is shown.

[0133] refer to Figure 5 , the terminal may include a radio frequency (RF) processor 5-10, a baseband processor 5-20, a memory 5-30, and a controller 5-40. The present disclosure is not limited to this example, and the terminal may include more than Figure 5 More or less configurations as shown in .

[0134] According to an embodiment of the present disclosure, the RF processor 5-10 can perform functions of sending or receiving signals via a wireless channel, such as frequency band conversion and amplification of signals. The RF processor 5-10 can up-convert the baseband signal provided from the baseband processor 5-20 into an RF band signal, and then send the RF band signal via an antenna, and down-convert the RF band signal received via the antenna into a baseband signal. For example, the RF processor 5-10 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a digital-to-analog converter (DAC), an analog-to-digital converter (ADC), etc. The present disclosure is not limited to the above examples. Figure 5 In the figure, only one antenna is shown, but the terminal may include multiple antennas. In addition, the RF processor 5-10 may include multiple RF chains. In addition, the RF processor 5-10 may perform beamforming. For beamforming, the RF processor 5-10 may adjust the phase and size of each of the signals sent and / or received via multiple antennas or antenna elements. In addition, the RF processor may perform multiple-input multiple-output (MIMO) and may receive multiple layers when performing MIMO operations.

[0135] According to an embodiment of the present disclosure, the baseband processor 5-20 can perform a conversion function between a baseband signal and a bit stream according to the physical layer standard of the system. For example, when data is transmitted, the baseband processor 5-20 can generate complex symbols by encoding and modulating the transmitted bit stream. In addition, when data is received, the baseband processor 5-20 can demodulate and decode the baseband signal provided from the RF processor 5-10 to recover the received bit stream. For example, according to an orthogonal frequency division multiplexing (OFDM) scheme, when data is transmitted, the baseband processor 5-20 can generate complex symbols by encoding and modulating the transmitted bit stream, and map the complex symbols to subcarriers, and then configure the OFDM symbol by an inverse fast Fourier transform (IFFT) operation and a cyclic prefix (CP) insertion. In addition, when data is received, the baseband processor 5-20 may divide the baseband signal provided from the RF processor 5-10 into units of OFDM symbols, and restore the signal mapped to the subcarriers through a fast Fourier transform (FFT) operation, and then restore the received bit stream through demodulation and decoding.

[0136] According to an embodiment of the present disclosure, the baseband processor 5-20 and the RF processor 5-10 may send and / or receive signals as described above. Therefore, the baseband processor 5-20 and the RF processor 5-10 may be referred to as a transmitter, a receiver, a transceiver, or a communicator. In addition, at least one of the baseband processor 5-20 and the RF processor 5-10 may include multiple communication modules to support a variety of different radio access technologies. In addition, at least one of the baseband processor 5-20 and the RF processor 5-10 may include different communication modules to process signals of different frequency bands. For example, different radio access technologies may include wireless LANs (e.g., IEEE 802.11), cellular networks (e.g., LTE), etc. In addition, different frequency bands may include super high frequency (SHF) (e.g., 2.NRHz, NRh) bands and millimeter wave (e.g., 60GHz) bands. The terminal may send or receive signals to or from a base station by using the baseband processor 5-20 and the RF processor 5-10, and the signal may include control information and data.

[0137] According to an embodiment of the present disclosure, the memory (or storage device (storage)) 5-30 may store data such as basic programs, applications, and configuration information for terminal operation. In particular, the memory 5-30 may store information related to a second access node that performs wireless communication by using a second radio access technology. In addition, the memory 5-30 may provide stored data according to a request of the controller 5-40. In addition, the memory 5-30 may include a plurality of memories. According to another embodiment, the memory 5-30 may store a program for executing the conditional specific cell change method described in the present disclosure.

[0138] According to an embodiment of the present disclosure, the controller 5-40 may control the overall operation of the terminal. For example, the controller 5-40 may send and / or receive signals through the baseband processor 5-20 and the RF processor 5-10. In addition, the controller 5-40 may record data on the memory 5-30 and read data from the memory 5-30. In order to record and read data, the controller 5-40 may include at least one processor. For example, the controller 5-40 may include a communication processor (CP) that controls communication and an application processor (AP) that controls the upper layer (e.g., application). In addition, at least one configuration in the terminal may be implemented as a single chip. In addition, according to an embodiment of the present disclosure, the controller 5-40 may include a multi-connection processor 5-42 that executes a process for operating in a multi-connection mode.

[0139] Figure 6 The structure of a base station according to an embodiment of the present disclosure is shown.

[0140] refer to Figure 6, the base station may include an RF processor 6-10, a baseband processor 6-20, a backhaul communicator 6-30, a memory 6-40, and a controller 6-50. The present disclosure is not limited to the above example, and the base station may include more Figure 6 The configuration shown in more or less. According to an embodiment of the present disclosure, the RF processor 6-10 can perform functions of sending and / or receiving signals via a wireless channel, such as frequency band conversion and amplification of the signal. The RF processor 6-10 can up-convert the baseband signal provided by the baseband processor 6-20 into an RF band signal, and then send the RF band signal via an antenna, and down-convert the RF band signal received via the antenna into a baseband signal. For example, the RF processor 6-10 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, etc. In Figure 6 In the figure, only one antenna is shown, but the first access node may include multiple antennas. In addition, the RF processor 6-10 may include multiple RF chains. In addition, the RF processor 6-10 may perform beamforming. For beamforming, the RF processor 6-10 may adjust the phase and size of each of the signals sent and / or received via multiple antennas or antenna elements. The RF processor may perform downlink MIMO operations by sending one or more layers.

[0141] According to an embodiment of the present disclosure, the baseband processor 6-20 can perform a conversion function between a baseband signal and a bit stream according to the physical layer standard of the first radio access technology. For example, when data is transmitted, the baseband processor 6-20 can generate complex symbols by encoding and modulating the transmission bit stream. In addition, when data is received, the baseband processor 6-20 can demodulate and decode the baseband signal provided from the RF processor 6-10 to recover the received bit stream. For example, according to the OFDM scheme, when data is transmitted, the baseband processor 6-20 can generate complex symbols by encoding and modulating the transmission bit stream and mapping the complex symbols to subcarriers, and then configure the OFDM symbol by IFFT operation and CP insertion. In addition, when data is received, the baseband processor 6-20 can divide the baseband signal provided from the RF processor 6-10 into OFDM symbol units, and recover the signal mapped to the subcarrier by FFT operation, and then recover the received bit stream by demodulation and decoding. The baseband processor 6-20 and the RF processor 6-10 can send and receive signals as described above. Therefore, the baseband processor 6-20 and the RF processor 6-10 may be referred to as a transmitter, a receiver, a transceiver, a communicator, or a wireless communicator.

[0142] According to an embodiment of the present disclosure, the backhaul communicator 6-30 may provide an interface for performing communication with other nodes in the network. The backhaul communicator 6-30 may convert a bit stream sent from a main base station to another node (e.g., an auxiliary base station, a core network, etc.) into a physical signal, and convert a physical signal received from another node into a bit stream.

[0143] According to an embodiment of the present disclosure, the memory (or storage device) 6-40 may store data such as basic programs, applications, and configuration information for the operation of the main base station. In particular, the memory 6-40 may store information about the bearer assigned to the access terminal, the measurement results reported from the access terminal, and the like. In addition, the memory 6-40 may store information used as a standard for determining whether to provide multiple connections to the terminal or to stop multiple connections. In addition, the memory 6-40 may provide stored data according to a request from the controller 6-50. In addition, the memory 6-40 may be configured as a storage medium or a combination of storage media such as ROM, RAM, hard disk, CD-ROM, and DVD. In addition, the memory 6-40 may include multiple memories. According to some embodiments, the memory 6-40 may store a program for executing the method for allocating IP addresses in the IAB system described in the present disclosure.

[0144] The controller 6-50 may control the overall operation of the base station. For example, the controller 6-50 may send and / or receive signals through the baseband processor 6-20 and the RF processor 6-10 or through the backhaul communicator 6-30. In addition, the controller 6-50 may record data on the memory 6-40 and read data from the memory 6-40. To this end, the controller 6-50 may include at least one processor. In addition, at least one configuration of the base station may be implemented as a single chip. In addition, according to various embodiments of the present disclosure, the controller 6-50 may control the operation of the base station or an entity corresponding thereto.

[0145] Furthermore, each configuration of the base station may be operable to perform the above-described embodiments of the present invention.

[0146] Hereinafter, terms used in the present disclosure are as follows.

[0147] SN: Secondary Node

[0148] MN: Master Node

[0149] MCG: Master Cell Group

[0150] SCG: Secondary Cell Group

[0151] Pcell: primary cell

[0152] PScell: Primary SCG (Secondary Cell Group) cell

[0153] SCell: Secondary cell

[0154] SpCell: Specific Cell

[0155] CHO: Conditional Switch

[0156] CPC: Conditional pscell changes

[0157] CPAC: Conditional pscell addition and change

[0158] S-SN: Source SN

[0159] T-SN: Target SN

[0160] S-MN: Source MN

[0161] T-MN: Target MN

[0162] SNModReq: SN modification request message

[0163] SNChangeReq: SN change request message

[0164] SNAddReq: SN add request message

[0165] SNAddReqACK: SN add request confirmation message

[0166] SNModConfirm: SN modification confirmation message

[0167] SI-CPC: CPC initiated by SN MI-CPC: CPC initiated by MN

[0168] Fig. 7A The CHO operation related to an embodiment of the present disclosure is shown.

[0169] Reference Fig. 7A In step 7a-05, when multi-radio access technology dual connectivity (MRDC) is configured for the terminal, the S-MN may determine to perform CHO and determine a target pcell and a T-MN.

[0170] In step 7a-10, the S-MN may send a HOReq message including target pcell information, the MCG of the terminal, configuration information (eg, SCG and / or MCG configuration information), and a conditional handover indicator to the T-MN.

[0171] In step 7a-15, the T-MN may determine the T-SN.

[0172] In step 7a-20, the T-MN may request resources for the terminal of the target pscell from the determined T-SN through an SNAddReq message.

[0173] In step 7a-25, the T-SN may determine a target pscell.

[0174] In step 7a-30, the T-SN may send the resource configuration information of the determined target pscell to the T-MN.

[0175] In step 7a-35, the T-MN may formulate (or generate) an RRC reconfiguration message including target MCG and target SCG configuration information based on the resource configuration information of the target pscell.

[0176] In step 7a-40, the T-MN may send a HOReaACK message including the formulated RRC Reconfiguration message to the S-MN.

[0177] In step 7a-45, the S-MN having received the HOReaACK message may send an SN Release Request (SNReleaseRequest) message to request the release of the existing S-SN.

[0178] In step 7a-50, the S-SN that has received the SN Release Request message may send a SN Release Request Acknowledgement (SNReleaseRequestACK) message to the S-MN in response to receiving the SN Release Request message.

[0179] In step 7a-55, the S-MN may connect (or associate) the RRC reconfiguration message received from the T-MN with a specific conditional reconfiguration Id, and formulate and associate conditions for connecting (or associating) with the received target MCG.

[0180] In step 7a-60, the S-MN may formulate a conditionalReconfiguration field including an id, a condition, and an RRCReconfiguration pair, and may send an RRCReconfiguration message including information about the conditionalReconfiguration field to the terminal.

[0181] In step 7a-65, the terminal may send an RRC reconfiguration complete message to the S-MN.

[0182] In steps 7a-70, when the RRC reconfiguration message is received, the terminal may start to check (or identify) the received condition.

[0183] In steps 7a-75, if a specific condition is met, the terminal may apply a target MCG and a target SCG configuration connected to (or associated with) the met condition.

[0184] In step 7a-80, the terminal may perform a random access (RA) procedure with the T-MN.

[0185] In step 7a-85, the terminal may send an RRC reconfiguration complete message to the T-MN.

[0186] In step 7a-90, after successfully applying the MCG and SCG configurations, the terminal may release the conditional reconfiguration variables as well as all entries of the measurement Id, report configuration and measurement objects associated only with the conditions of CHO.

[0187] In step 7a-95, the T-MN may send an SN reconfiguration complete message to the T-SN.

[0188] Figure 7B The structure of CHO configuration information related to the embodiment of the present disclosure is shown.

[0189] refer to Figure 7B , describes the structure of CHO configuration information sent to the terminal. CHO configuration information (e.g., conditional reconfiguration) may include a conditional reconfiguration ID (condReconfig ID), a condition (Condition) from an S-MN measurement configuration (measConfig), and / or a conditional RRC reconfiguration (condRRCReconfig) (RRC reconfiguration (RRCReconfig)). In addition, the conditional RRC reconfiguration (RRC reconfiguration) may include a target MCG configuration, a target SCG configuration for pscell configuration, and / or include or not include a synchronization reconfiguration (reconfigWithSync).

[0190] In the technology provided below, when the measurement configuration related to the signal strength comparison between the source pcell and the candidate pcell is called type 1 condition, and the measurement configuration related to the signal strength comparison between the source pscell and the candidate pscell or only related to the signal strength comparison of the candidate pscell is called type 2 condition, a combination of type 1 condition and type 2 condition can be introduced as a performance condition for conditional switching.

[0191] It is required that both the type 1 condition and the type 2 condition are included in the measurement configuration provided by the S-MN so as to be introduced as performance conditions for conditional switching, and the S-MN may configure the measurement operation of the type 1 condition or the type 2 condition to the terminal before indicating the type 1 condition or the type 2 condition to the terminal or simultaneously with the indication. In the case of the type 2 condition, the subject that determines the condition may be the T-MN, the S-MN, or the T-SN. When the subject that determines the condition is the T-MN or the T-SN, a process of sending measurement configuration information related to the condition to the S-MN may be required. When the subject that determines the condition is the T-MN, the following reference is made to Fig. 8A When the subject of the determination condition is T-SN, the following reference Fig.9A A detailed description is given. The S-MN that has received the measurement configuration information related to the condition can use the received information to configure the measurement operation associated with the type 2 condition. In addition, the S-MN can formulate the conditions for a specific target MCG for conditional switching by using the type 1 condition and the type 2 condition.

[0192] The first method may define that the conditions for a specific target MCG are met only when both the Type 1 condition and the Type 2 condition are met. In the second method, both the Type 1 condition and the Type 2 condition may be checked (or identified), and the case where only the Type 1 condition is met at a specific point in time and the case where both the Type 1 condition and the Type 2 condition are met may be considered separately in operation. In particular, when only the Type 1 condition is met, the terminal may apply only the MCG configuration in the connected (or associated) RRC reconfiguration. If both the Type 1 condition and the Type 2 condition are met, the S-MN may apply all specific target configurations. That is, the S-MN may apply both the target MCG configuration and the target SCG configuration.

[0193] Fig. 8A The operation of performing CHO is shown when both the Type 1 condition and the Type 2 condition are satisfied, wherein the T-MN determines the Type 2 condition.

[0194] refer to Fig. 8A In step 8a-05, when MRDC is configured for the terminal, the S-MN may determine to perform CHO and determine the target pcell and T-MN.

[0195] In steps 8a-10, the S-MN may send a HOReq message including target pcell information, the MCG of the terminal, configuration information (eg, SCG or MCG configuration information), and a conditional handover indicator to the T-MN.

[0196] In step 8a-15, the T-MN may determine the T-SN.

[0197] In step 8a-20, the T-MN may request resources for the terminal of the target pscell from the determined T-SN through an SNAddReq message.

[0198] In step 8a-25, the T-SN may determine the target pscell and determine configuration information. The configuration information may also include at least one of the PCI, CGI and frequency information of the determined pscell and target pscell (SCG) information.

[0199] In step 8a-30, the T-SN may send a SNAddReqACK message including configuration information and target pscell (SCG) information to the T-MN.

[0200] In step 8a-35, the T-MN may determine the MCG configuration information by determining the target pcell received from the S-MN. In addition, the T-MN may formulate (or generate) an RRC reconfiguration message including the target SCG configuration information received from the T-SN. In addition, the T-MN may determine the conditions for CPA or CPC.

[0201] In step 8a-40, the T-MN may send measurement configuration information for implementing the determined conditions for CPA or CPC to the S-MN. The measurement configuration information may include one or more of the following information.

[0202] Information about the frequency of the target pscell and the PCI, CGI, reporting configuration, conditional event type (cond (condition) A4 and / or condA3 and / or condA5), offset value, RS type (SSB and / or CSI-RS) and measurement type (RSRQ and / or RSRP and / or RSSI) of the target pscell.

[0203] The T-MN may send a HOReqACK message including the formulated (or generated) RRC reconfiguration message and conditional measurement configuration information for the pscell to the S-SN.

[0204] In step 8a-45, the S-MN may receive the HOReqACK message and may request SN Release (SNRelease) from the S-SN.

[0205] In step 8a-50, when the S-SN receives the SN release request message from the S-MN, the S-SN may send a response to the SN release request message (eg, SN release request confirmation) to the S-MN.

[0206] In step 8a-55, the S-MN that has received information related to the pscell condition (e.g., type 2) can establish a measurement object (MO) corresponding to the pscell condition for the pscell condition information, and formulate a report configuration to formulate a measurement ID including the MO and the report configuration. In addition, the S-MN can formulate a condition for conditional switching for the target pcell of the T-MN (or the target MCG of the T-MN) (e.g., type 1). The condition for conditional switching may be included in the measurement configuration information of the S-MN. In addition, the S-MN may determine a condition set obtained by combining a predetermined number of type 1 conditions and a predetermined number of type 2 conditions by a logical operator "AND" as a performance condition for conditional switching to the target MCG of the T-MN, and may combine the performance condition for conditional switching to the target MCG of the T-MN, the conditional reconfiguration ID, and the RRC reconfiguration connection (or association) received from the T-Mn into one condition.

[0207] In step 8a-60, the S-MN may send an RRC reconfiguration message including the information configured in step 8a-55 to the terminal.

[0208] In step 8a-65, the terminal may send an RRC reconfiguration complete message to the S-MN in response to the RRC reconfiguration message.

[0209] In step 8a-70, the terminal having received the RRC reconfiguration message may check (or identify) a condition for conditional switching.

[0210] In step 8a-75, if any one item condition of the type 1 condition and type 2 condition combination set is met, the terminal may apply the target MCG and target SCG configurations connected (or associated) with the met condition.

[0211] In step 8a-80, the terminal may perform a RA procedure with the T-MN.

[0212] In steps 8a-85, the terminal may send an RRC reconfiguration complete message to the T-MN.

[0213] In step 8a-90, if the application of the MCG and SCG configurations is successful, the terminal may delete all conditional switching configuration information in the terminal's internal variables.

[0214] In step 8a-95, the T-MN may send an SN reconfiguration complete message to the T-SN.

[0215] Figure 8B The structure of CHO configuration information according to an embodiment of the present disclosure is shown.

[0216] refer to Figure 8B , describes the structure of CHO configuration information sent to the terminal. The CHO configuration information (e.g., conditional reconfiguration) may include a conditional reconfiguration ID, conditions (type 1 conditions and type 2 conditions) from the MN measurement configuration, and / or a measurement configuration (RRC reconfiguration). In addition, the conditional RRC reconfiguration (RRC reconfiguration) may include a target MCG configuration, a target SCG configuration for pscell configuration, and / or include or not include synchronization reconfiguration.

[0217] Fig.9A An operation of performing CHO when both Type 1 conditions and Type 2 conditions are satisfied according to an embodiment of the present disclosure is illustrated, wherein the T-SN determines the Type 2 condition.

[0218] refer to Fig.9A In step 9a-05, when MRDC is configured for the terminal, the S-MN may determine to perform CHO and determine the target pcell and T-MN.

[0219] In steps 9a-10, the S-MN may send a HOReq message including target pcell information, MCG of the terminal, configuration information (eg, SCG or MCG configuration information), and a conditional handover indicator to the T-MN.

[0220] In step 9a-15, the T-MN may determine the T-SN.

[0221] In step 9a-20, the T-MN may request resources for the terminal of the target PSCell from the determined T-SN through an SNAddReq message.

[0222] In step 9a-25, the T-SN may determine the target pscell, determine configuration information, and determine conditions for CPA or CPC. In addition, the T-SN may determine parameters corresponding to the conditions for CPA or CPC (e.g., MO, frequency, and / or report configuration (ReportConfig) in the target pscell).

[0223] In step 9a-30, the T-SN may send measurement configuration information for implementing the determined conditions for CPA or CPC to the T-MN. The measurement configuration information for implementing the conditions for CPA or CPC may include one or more of the following information.

[0224] Information about the frequency of the target pscell and the PCI, CGI, reporting configuration, conditional event type (condA4 and / or condA3 and / or condA5), offset value, RS type (SSB and / or CSI-RS), and measurement type (RSRQ and / or RSRP and / or RSSI) of the target pscell.

[0225] The T-SN may send an SNAddReqACK message including target pscell (SCG) information and measurement configuration information for implementing conditions for CPA or CPC to the T-MN.

[0226] In step 9a-35, the T-MN may determine the MCG configuration information by determining the target pcell. In addition, the T-MN may formulate (or generate) an RRC reconfiguration message including the target SCG configuration information received from the T-SN.

[0227] In step 9a-40, the T-MN may send the condition information of the target pscell (SCG) received from the T-SN to the S-MN. The T-MN may send a HOReqACK message including the formulated (or generated) RRC reconfiguration message and the measurement configuration information for the condition of the pcell to the S-SN.

[0228] In step 9a-45, the S-MN may receive the HOReqACK message and may request SN release from the S-SN.

[0229] In step 9a-50, when the S-SN receives the SN release request message from the S-MN, the S-SN may send a response to the SN release request message (eg, SN release request confirmation) to the S-MN.

[0230] In step 9a-55, the S-MN that has received information related to the pscell condition (e.g., type 2) can establish an MO corresponding to the pscell condition information for the pscell, and formulate a report configuration to formulate a measurement ID including the MO and the report configuration. In addition, the S-MN can formulate a condition for conditional switching for the target pcell of the T-MN (or the target MCG of the T-MN) (e.g., type 1). In addition, the S-MN can determine a condition set obtained by combining a predetermined number of type 1 conditions and a predetermined number of type 2 conditions by a logical operator "and" as a performance condition for conditional switching to the target MCG of the T-MN, and can combine the performance condition for conditional switching to the target MCG of the T-MN, the condition reconfiguration ID, and the RRC reconfiguration connection (or association) received from the T-Mn into one condition.

[0231] In step 9a-60, the S-MN may send an RRC reconfiguration message including the information configured in step 9a-55 to the terminal.

[0232] In step 9a-65, the terminal may send an RRC reconfiguration complete message to the S-MN in response to the RRC reconfiguration message. In step 9a-70, the terminal having received the RRC reconfiguration message may check (or identify) a condition for conditional switching.

[0233] In step 9a-75, if any one condition of the type 1 condition and type 2 condition combination set is met, the terminal may apply the target MCG and target SCG configurations connected (or associated) with the met condition.

[0234] In step 9a-80, the terminal may perform a RA procedure with the T-MN.

[0235] In step 9a-85, the terminal may send an RRC reconfiguration complete message to the T-MN.

[0236] In step 9a-90, if the application of the MCG and SCG configurations is successful, the terminal may delete all conditional switching configuration information in the terminal's internal variables.

[0237] In step 9a-95, the T-MN may send an SN reconfiguration complete message to the T-SN.

[0238] Fig. 9B The structure of CHO configuration information according to an embodiment of the present disclosure is shown.

[0239] refer to Fig. 9B , describes the structure of CHO configuration information sent to the terminal. The CHO configuration information (e.g., conditional reconfiguration) may include a conditional reconfiguration ID, conditions (type 1 conditions and type 2 conditions) from the MN measurement configuration, and / or a conditional RRC reconfiguration (RRC reconfiguration). In addition, the conditional RRC reconfiguration (RRC reconfiguration) may include a target MCG configuration, a target SCG configuration for pscell configuration, and / or include or not include synchronization reconfiguration.

[0240] Fig. 10A It is shown that it is determined whether each of the type 1 condition and the type 2 condition is satisfied and an operation of CHO is performed when the SCG is applied hierarchically according to an embodiment of the present disclosure, wherein the T-MN determines the type 2 condition.

[0241] Reference Fig. 10A In step 10a-05, when MRDC is configured for the terminal, the S-MN may determine to perform CHO and determine the target pcell and T-MN.

[0242] In step 10a-10, the S-MN may send a HOReq message including target pcell information, MCG of the terminal, configuration information (eg, SCG or MCG configuration information), and a conditional handover indicator to the T-MN.

[0243] In step 10a-15, the T-MN may determine the T-SN.

[0244] In step 10a-20, the T-MN may request resources for the terminal of the target PSCell from the determined T-SN through an SNAddReq message.

[0245] In step 10a-25, the T-SN may determine the target PSCell and determine configuration information.

[0246] In step 10a-30, the T-SN may send a SNAddReqACK message including configuration information and target pscell (SCG) information to the T-MN. In addition, the configuration information may include at least one of the PCI, CGI, and frequency information of the determined pscell.

[0247] In step 10a-35, the T-MN having received the configuration information may determine the MCG configuration information by determining the target pcell. In addition, the T-MN may formulate (or generate) an RRC reconfiguration message including the target SCG configuration information received from the T-SN. In addition, the T-MN may determine the conditions for CPA or CPC. In addition, the T-MN may determine parameters corresponding to the conditions for CPA or CPC (e.g., MO, frequency, and / or reporting configuration in the target pscell).

[0248] In step 10a-40, the T-MN may send measurement configuration information for implementing the conditions for CPA or CPC to the S-MN. The measurement configuration information for implementing the conditions for CPA or CPC may include one or more of the following information.

[0249] Information about the frequency of the target pscell and the PCI, CGI, reporting configuration, conditional event type (condA4 and / or condA3 and / or condA5), offset value, RS type (SSB and / or CSI-RS), and measurement type (RSRQ and / or RSRP and / or RSSI) of the target pscell.

[0250] The T-MN may send a HOReqACK message including the formulated RRC reconfiguration message and conditional measurement configuration information for the pscell to the S-SN.

[0251] In step 10a-45, the S-MN may receive the HOReqACK message and may request SN release from the S-SN.

[0252] In step 10a-50, when the S-SN receives the SN release request message from the S-MN, the S-SN may send a response to the SN release request message (eg, SN release request confirmation) to the S-MN.

[0253] In step 10a-55, the S-MN that has received information related to the pscell condition (e.g., type 2) can establish an MO corresponding to the pscell condition information for the pscell, and formulate a report configuration to formulate a measurement ID including the MO and the report configuration. In addition, the S-MN can formulate a condition for conditional switching for the target pcell of the T-MN (or the target MCG of the T-MN) (e.g., type 1). In addition, the S-MN can determine a predetermined number of type 1 conditions and a predetermined number of type 2 conditions as performance conditions for conditional switching to the target MCG of the T-MN through a separate indicator, and can combine the performance conditions for conditional switching to the target MCG of the T-MN, the conditional reconfiguration Id, and the RRC reconfiguration connection (or association) received from the T-Mn into one condition.

[0254] In step 10a-60, the S-MN may send an RRC reconfiguration message including the information configured in step 10a-55 to the terminal.

[0255] In step 10a-65, the terminal may send an RRC reconfiguration complete message to the S-MN in response to the RRC reconfiguration message.

[0256] In step 10a-70, the terminal having received the RRC reconfiguration message may check (or identify) a condition for conditional switching.

[0257] In step 10a-75, when the type 1 condition is met, the terminal may check (or identify) whether the type 2 condition is met. Depending on whether the type 2 condition is met, when only the type 1 condition is met, the terminal may apply the target MCG configuration. Alternatively, when both the type 1 condition and the type 2 condition are met, the terminal may apply all configurations (e.g., the target MCG and target SCG configurations).

[0258] In step 10a-80, the terminal may perform a RA procedure with the T-MN.

[0259] In step 10a-85, if the application of the type 1 condition or all types of conditions (e.g., the type 1 condition and the type 2 condition) is successful, the terminal may send an RRC reconfiguration complete (RRCReconfigurationComplete) message to the T-MN. In this case, the RRC reconfiguration complete message may include an indicator indicating that all types of conditions (e.g., the type 1 condition and the type 2 condition) are satisfied.

[0260] In an embodiment, when only all type 1 condition sets are met, the terminal may apply the MCG configuration and other common configurations. In this case, other common configurations may refer to all configurations except the mrdc-SCG configuration (e.g., measurement configuration, radio bearer configuration, etc.). In addition, if the SCG was previously configured, the terminal may release the configured SCG. Alternatively, if the SCG was not previously configured, the terminal may not configure a separate SCG. If the MCG application is successful, the terminal may send an RRC reconfiguration completion message to the T-MN. In this case, the RRC reconfiguration completion message may include an indicator indicating that only type 1 is met or only the MCG is met successfully.

[0261] In step 10a-90, if the application of the MCG and SCG configurations is successful, the terminal may delete all conditional switching configuration information in the terminal's internal variables.

[0262] In step 10a-95, the T-MN may send an SN reconfiguration complete message to the T-SN.

[0263] Fig. 10B The structure of CHO configuration information according to an embodiment of the present disclosure is shown.

[0264] refer to Fig. 10B , describes the structure of CHO configuration information sent to the terminal. CHO configuration information (e.g., conditional reconfiguration) may include a conditional reconfiguration ID, conditions from MN measurement configuration (type 1 measurement Id (measId), type 2 measurement Id), and / or a conditional RRC reconfiguration (RRC reconfiguration). In addition, the conditional RRC reconfiguration (RRC reconfiguration) may include a target MCG configuration, a target SCG configuration for pscell configuration, and / or include or not include synchronization reconfiguration.

[0265] Fig.11A It is shown that it is determined whether each of the Type 1 condition and the Type 2 condition is satisfied according to an embodiment of the present disclosure, and an operation of CHO is performed when the SCG is applied hierarchically, wherein the T-SN determines the Type 2 condition.

[0266] Reference Fig.11AIn step 11a-05, when MRDC is configured for the terminal, the S-MN may determine to perform CHO and determine the target pcell and T-MN.

[0267] In step 11a-10, the S-MN may send a HOReq message including target pcell information, MCG of the terminal, configuration information (eg, SCG or MCG configuration information), and a conditional handover indicator to the T-MN.

[0268] In step 11a-15, the T-MN may determine the T-SN.

[0269] In step 11a-20, the T-MN may request resources for the terminal of the target pscell from the determined T-SN through an SNAddReq message.

[0270] In step 11a-25, the T-SN may determine a target pscell, determine configuration information, and determine conditions for CPA or CPC. In addition, the T-SN may determine parameters corresponding to the conditions for CPA or CPC (e.g., MO, frequency, and / or reporting configuration in the target pscell).

[0271] In step 11a-30, the T-SN may send measurement configuration information for implementing the determined condition for CPA or CPC to the T-MN. The measurement configuration information for implementing the condition for CPA or CPC may include one or more of the following information.

[0272] - Information about the frequency where the target pscell is located and the PCI, CGI, reporting configuration, conditional event type (condA4 and / or condA3 and / or condA5), offset value, RS type (SSB and / or CSI-RS), and measurement type (RSRQ and / or RSRP and / or RSSI) of the target pscell. The T-SN may send an SNAddReqACK message including the target pscell (SCG) information and measurement configuration information for implementing conditions for CPA or CPC to the T-MN.

[0273] In step 11a-35, the T-MN may determine the MCG configuration information by determining the target pcell. In addition, the T-MN may formulate (or generate) an RRC reconfiguration message including the target SCG configuration information received from the T-SN.

[0274] In step 11a-40, the T-MN may send the condition information of the target pscell (SCG) received from the T-SN to the S-MN. The T-MN may send a HOReqACK message including the formulated (or generated) RRC reconfiguration message and the measurement configuration information for the condition of the PSCell to the S-SN.

[0275] In step 11a-45, the S-MN may receive the HOReqACK message and may request SN release from the S-SN.

[0276] In step 11a-50, when the S-SN receives the SN release request message from the S-MN, the S-SN may send a response to the SN release request message (eg, SN release request confirmation) to the S-MN.

[0277] In step 11a-55, the S-MN that has received information related to the pscell condition (e.g., type 2) can establish an MO corresponding to the condition information of the pscell for the condition information of the pscell, and formulate a report configuration to formulate a measurement ID including the MO and the report configuration. In addition, the S-MN can formulate conditions for conditional switching for the target pcell of the T-MN (or the target MCG of the T-MN) (e.g., type 1). In addition, the S-MN can determine a condition set obtained by combining a predetermined number of type 1 conditions and a predetermined number of type 2 conditions by a logical operator "and" as a performance condition for conditional switching to the target MCG of the T-MN, and can combine the performance condition for conditional switching to the target MCG of the T-MN, the condition reconfiguration ID, and the RRC reconfiguration connection (or association) received from the T-Mn into one condition.

[0278] In step 11a-60, the S-MN may send an RRC reconfiguration message including the information configured in step 11a-55 to the terminal.

[0279] In step 11a-65, the terminal may send an RRC reconfiguration complete message to the S-MN in response to the RRC reconfiguration message.

[0280] In step 11a-70, the terminal having received the RRC reconfiguration message may check (or identify) a condition for conditional switching.

[0281] In step 11a-75, when the type 1 condition is satisfied, the terminal may check (or identify) whether the type 2 condition is satisfied. Depending on whether the type 2 condition is satisfied, when only the type 1 condition is satisfied, the terminal may apply the target MCG configuration. Alternatively, when both the type 1 condition and the type 2 condition are satisfied, the terminal may apply all configurations (e.g., the target MCG and target SCG configurations).

[0282] In step 11a-80, the terminal may perform a RA procedure with the T-MN.

[0283] In step 11a-85, if the application of the type 1 condition or all types of conditions (e.g., the type 1 condition and the type 2 condition) is successful, the terminal may send an RRC reconfiguration complete message to the T-MN. In this case, the RRC reconfiguration complete message may include an indicator indicating that all types of conditions (e.g., the type 1 condition and the type 2 condition) are satisfied.

[0284] In an embodiment, when only all type 1 condition sets are met, the terminal may apply the MCG configuration and other common configurations. In this case, other common configurations may refer to all configurations except the mrdc-SCG configuration (e.g., measurement configuration, radio bearer configuration, etc.). In addition, if the SCG was previously configured, the terminal may release the configured SCG. Alternatively, if the SCG was not previously configured, the terminal may not configure a separate SCG. If the MCG application is successful, the terminal may send an RRC reconfiguration completion message to the T-MN. In this case, the RRC reconfiguration completion message may include an indicator indicating that only type 1 is met or only the MCG is met successfully.

[0285] In step 11a-90, if the application of the MCG and SCG configurations is successful, the terminal may delete all corresponding conditional switching configuration information in the terminal's internal variables.

[0286] In step 11a-95, the T-MN may send an SN reconfiguration complete message to the T-SN.

[0287] In an embodiment, when only the Type 1 condition is satisfied and the Type 2 condition is not satisfied, the terminal may perform one of the following operations after applying the MCG configuration.

[0288] 1) Release the type 2 conditional configuration information, 2) Maintain the type 2 conditional configuration information, or 3) Maintain the timer.

[0289] If the terminal releases the type 2 condition configuration information, the terminal can perform the SN addition process initiated by the MN after applying the MCG configuration. If the terminal maintains the type 2 condition configuration information, the terminal can also maintain the type 2 condition set. Therefore, even after the MCG configuration, the terminal can check (or identify) the type 2 condition, and if the type 2 condition is met, the target SCG can be applied. In the case of using a timer, the T-SN can send an SNAddReqACK message to the terminal via the T-MN and S-MN. The timer can start from the time point when the target SCG configuration information is sent to the terminal. When the timer expires, the terminal can delete the measurement configuration information related to the type 2 condition and the target SCG configuration information in the terminal variables.

[0290] Fig. 11B The structure of CHO configuration information according to an embodiment of the present invention is shown.

[0291] refer to Fig. 11B , describes the structure of CHO configuration information sent to the terminal. The CHO configuration information (e.g., conditional reconfiguration) may include a conditional reconfiguration ID, conditions from the MN measurement configuration (Type 1 Measurement Id, Type 2 Measurement Id), and / or a conditional RRC reconfiguration (RRC reconfiguration). In addition, the conditional RRC reconfiguration (RRC reconfiguration) may include a target MCG configuration, a target SCG configuration for pscell configuration, and / or include or not include synchronization reconfiguration.

[0292] The methods according to the embodiments described in the claims or specification of the present disclosure may be implemented in software, hardware, or a combination of hardware and software.

[0293] For software, a computer-readable storage medium storing one or more programs (software modules) may be provided. One or more programs stored in the computer-readable storage medium may be configured to be executed by one or more processors of an electronic device. One or more programs may include instructions for controlling an electronic device to perform a method according to an embodiment described in the claims or specification of the present disclosure.

[0294] Such a program (software module, software) may be stored in a random access memory, a non-volatile memory including flash memory, a read-only memory (ROM), an electrically erasable programmable ROM (EEPROM), a magnetic disk storage device, a compact disk (CD)-ROM, a digital versatile disk (DVD) or other optical storage device, and a magnetic tape cassette. Alternatively, such a program may be stored in a memory that combines some or all of those recording media. A plurality of memories may be included.

[0295] In addition, the program may be stored in an attachable storage device accessible via a communication network such as the Internet, an intranet, a local area network (LAN), a wide area network (WLAN), or a storage area network (SAN), or via a communication network that combines these networks. Such a storage device may access the apparatus for executing the embodiments of the present disclosure through an external port. In addition, a separate storage device on a communication network may access the apparatus for executing the embodiments of the present disclosure.

[0296] In the specific embodiments of the present disclosure, the components included in the present disclosure are expressed in singular or plural form. However, for ease of explanation, singular or plural expression is appropriately selected according to the provided situation, the present disclosure is not limited to a single component or multiple components, a component expressed in plural form can be configured as a single component, and a component expressed in singular form can be configured as multiple components.

[0297] At the same time, although specific embodiments have been described in the explanation of the present disclosure, it should be noted that various changes can be made here without departing from the scope of the present disclosure. Therefore, the scope of the present disclosure is not limited or defined by the described embodiments, and the scope of the present disclosure is limited not only by the scope of the following claims, but also by its equivalents.

[0298] The embodiments of the present disclosure described and shown in the specification and the drawings are merely specific examples provided for the convenience of explaining the technical content of the present disclosure and to help understand the present disclosure, and are not intended to limit the scope of the present disclosure. That is to say, it is obvious to those skilled in the art that other variations based on the technical ideas of the present disclosure can be implemented. In addition, the above-mentioned various embodiments can be used in combination as needed. For example, a part of one embodiment of the present invention can be combined with a part of another embodiment to operate a base station and a terminal. As an example, a part of embodiment 1 of the present disclosure can be combined with a part of embodiment 2 to operate a base station and a terminal. In addition, although the above-mentioned embodiments are proposed based on an FDD LTE system, other variations based on the technical ideas of the above-mentioned embodiments can also be implemented in other systems such as TDD LTE, 5G or NR systems.

[0299] In the drawings describing the methods of the present disclosure, the order of description does not always correspond to the order of performing the steps of each method, and the sequential relationship between the steps may be changed or the steps may be performed in parallel.

[0300] Alternatively, in the drawings describing the method of the present invention, some elements may be omitted and only some elements may be included without departing from the basic spirit and scope of the present invention.

[0301] Furthermore, in the method of the present disclosure, some or all of the contents of each embodiment may be implemented in combination without departing from the basic spirit and scope of the present disclosure.

[0302] Various embodiments of the present disclosure have been described above. The above description of the present disclosure is for illustrative purposes only, and the embodiments of the present disclosure are not limited to the embodiments set forth herein. Those skilled in the art will appreciate that the present disclosure can be easily modified and changed into other specific forms without departing from the technical ideas or essential features of the present invention. Therefore, the scope of the present disclosure should not be determined by the above detailed description, but by the appended claims, and all modifications and changes derived from the meaning and scope of the claims and their equivalents should be interpreted as falling within the scope of the present disclosure.

Claims

1. A method performed by a user equipment UE in a wireless communication system, the method comprising: Receiving a measurement configuration from a source master node S-MN, the measurement configuration comprising a first condition for conditional handover CHO and a second condition for conditional primary and secondary cell group cell PSCell change CPC; as well as In case both the first condition and the second condition are satisfied, the CHO to the target master node T-MN is performed and the CPC to the target secondary node T-SN is performed.

2. The method according to claim 1, wherein: The measurement configuration is included in a radio resource control (RRC) reconfiguration message, and The RRC reconfiguration message further includes: a primary cell group MCG configuration associated with the T-MN and a secondary cell group SCG configuration associated with the T-SN.

3. The method according to claim 2, wherein: The CHO is performed based on the MCG configuration associated with the T-MN, and the CPC is performed based on the SCG configuration associated with the T-SN, and Wherein, in a case where only the first condition is met, the CHO to the T-MN is performed based on the MCG configuration associated with the T-MN.

4. The method according to claim 1, wherein: The first condition related to at least one candidate primary cell PCell for the CHO, determined by the S-MN, is based on the measurement configuration of the S-MN.

5. A method performed by a source master node S-MN in a wireless communication system, the method comprising: Receiving a second condition from the candidate master node MN; as well as Sending a measurement configuration to the source master node S-MN, the measurement configuration including a first condition for conditional handover CHO and a second condition for conditional primary and secondary cell group cell PSCell change CPC, Wherein, in the case where both the first condition and the second condition are satisfied, the CHO to the candidate master node as the target master node T-MN is performed and the CPC to the target secondary node T-SN is performed.

6. The method according to claim 5, wherein: The measurement configuration is included in a radio resource control RRC reconfiguration message, and The RRC reconfiguration message further includes: a primary cell group MCG configuration associated with the T-MN and a secondary cell group SCG configuration associated with the T-SN.

7. The method according to claim 6, wherein: The CHO is performed based on the MCG configuration associated with the T-MN, and the CPC is performed based on the SCG configuration associated with the T-SN, and Wherein, in a case where only the first condition is met, the CHO to the T-MN is performed based on the MCG configuration associated with the T-MN.

8. The method according to claim 5, wherein: The first condition related to at least one candidate primary cell PCell for the CHO, determined by the S-MN, is based on the measurement configuration of the S-MN.

9. A user equipment UE in a wireless communication system, the UE comprising: Transceiver; as well as at least one processor coupled to the transceiver and configured to: receiving a measurement configuration from a source master node S-MN, the measurement configuration comprising a first condition for conditional handover CHO and a second condition for conditional primary and secondary cell group cell PSCell change CPC, and In case both the first condition and the second condition are satisfied, the CHO to the target master node T-MN is performed and the CPC to the target secondary node T-SN is performed.

10. The UE according to claim 9, wherein: The measurement configuration is included in a radio resource control RRC reconfiguration message, and The RRC reconfiguration message further includes: a primary cell group MCG configuration associated with the T-MN and a secondary cell group SCG configuration associated with the T-SN.

11. The UE according to claim 10, wherein: The CHO is performed based on the MCG configuration associated with the T-MN, and the CPC is performed based on the SCG configuration associated with the T-SN, and Wherein, in a case where only the first condition is met, the CHO to the T-MN is performed based on the MCG configuration associated with the T-MN.

12. The UE according to claim 9, wherein: The first condition related to at least one candidate primary cell PCell for the CHO, determined by the S-MN, is based on the measurement configuration of the S-MN.

13. A source master node S-MN in a wireless communication system, the S-MN comprising: Transceiver; as well as at least one processor coupled to the transceiver and configured to: Receiving a second condition from the candidate master node MN; as well as Sending a measurement configuration to the source master node S-MN, the measurement configuration including a first condition for conditional handover CHO and a second condition for conditional primary and secondary cell group cell PSCell change CPC, Wherein, in the case where both the first condition and the second condition are satisfied, the CHO to the candidate master node as the target master node T-MN is performed and the CPC to the target secondary node T-SN is performed.

14. The S-MN according to claim 13, wherein: The measurement configuration is included in a radio resource control RRC reconfiguration message, and The RRC reconfiguration message further includes a primary cell group MCG configuration associated with the T-MN and a secondary cell group SCG configuration associated with the T-SN.

15. The S-MN according to claim 14, wherein: The CHO is performed based on the MCG configuration associated with the T-MN, and the CPC is performed based on the SCG configuration associated with the T-SN, and Wherein, in a case where only the first condition is met, the CHO to the T-MN is performed based on the MCG configuration associated with the T-MN.

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