Method and apparatus for applying reference configuration for subsequent conditional pscell addition or change in next-generation wireless communication system

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting higher data transfer rates. A method performed by a master node (MN) in a wireless communication system, according to an embodiment of the present disclosure, comprises the steps of: receiving, from a source secondary node (SN), an SN change request message for a subsequent conditional primary secondary cell group (SCG) cell (PSCell) addition or change (CPAC), wherein the SN change request message includes a secondary cell group (SCG) reference configuration; transmitting, to a candidate SN, an SN addition request message including the SCG reference configuration; receiving, from the candidate SN, an SN addition request acknowledgment message including a configuration for a candidate PSCell; and for the subsequent CPAC, transmitting, to UE, a reference configuration and the configuration for the candidate PSCell, wherein the reference configuration includes the SCG reference configuration and a master cell group (MCG) reference configuration generated by the MN.

Description

Method and device for applying reference settings for subsequent conditional PSCELL addition or modification in next-generation wireless communication systems

[0001] The present disclosure relates to a wireless communication system, and more particularly, to a method and apparatus for applying a reference setting for subsequent conditional PSCell addition or change (SCPAC) of a primary SCG (secondary cell group) cell.

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

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

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

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

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

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

[0008] The present disclosure provides a method and apparatus for applying a reference setting for subsequent conditional PSCell addition or modification.

[0009] In a wireless communication system according to an embodiment of the present disclosure, a method performed by a master node (MN) includes the steps of: receiving, from a source secondary node (SN), an SN change request message for a subsequent CPAC (conditional PSCell (primary SCG (secondary cell group) cell) addition or change), the SN change request message including an SCG (secondary cell group) reference configuration, transmitting, to a candidate SN, an SN addition request message including the SCG reference configuration, receiving, from the candidate SN, an SN addition request acknowledgement message including a configuration for a candidate PSCell, and transmitting, for the subsequent CPAC, a reference configuration and a configuration for the candidate PSCell to a terminal, wherein the reference configuration may include the SCG reference configuration and an MCG (master cell group) reference configuration generated by the MN.

[0010] In a wireless communication system according to one embodiment of the present disclosure, a method performed by a terminal includes the steps of receiving a reference setting and a setting for a candidate PSCell from an MN for a subsequent CPAC, and determining whether to execute the subsequent CPAC based on the reference setting and the setting for the candidate PSCell, wherein the reference setting includes an SCG reference setting transmitted from a source SN to the MN and an MCG reference setting generated by the MN, and the setting for the candidate PSCell can be transmitted from the candidate SN to the MN.

[0011] In a wireless communication system according to one embodiment of the present disclosure, an MN includes a transceiver and a control unit, and the control unit is configured to receive, from a source SN, an SN change request message for a subsequent CPAC, wherein the SN change request message includes an SCG reference setting, and to transmit an SN addition request message including the SCG reference setting to a candidate SN, and to receive, from the candidate SN, an SN addition request acknowledgment message including a setting for a candidate PSCell, and to transmit a reference setting and a setting for the candidate PSCell to a terminal for the subsequent CPAC, wherein the reference setting may include the SCG reference setting and an MCG reference setting generated by the MN.

[0012] In a wireless communication system according to one embodiment of the present disclosure, a terminal includes a transceiver and a control unit, and the control unit is configured to receive, from an MN, a reference setting and a setting for a candidate PSCell for a subsequent CPAC, and to determine whether to execute the subsequent CPAC based on the reference setting and the setting for the candidate PSCell, wherein the reference setting includes an SCG reference setting transmitted from a source SN to the MN and an MCG reference setting generated by the MN, and the setting for the candidate PSCell can be transmitted from a candidate SN to the MN.

[0013] According to one embodiment of the present disclosure, it is possible to identify an entity that determines a reference configuration and a delta configuration when performing a subsequent conditional PSCell addition or change.

[0014] Additionally, according to one embodiment of the present disclosure, a complete configuration can be configured by combining a reference configuration and a delta configuration, and the final complete configuration can be applied when performing subsequent conditional PSCell addition or change.

[0015] FIG. 1 is a diagram illustrating the structure of an LTE (long term evolution) system according to one embodiment of the present disclosure.

[0016] FIG. 2 is a diagram illustrating a wireless protocol structure of an LTE system according to an embodiment of the present disclosure.

[0017] FIG. 3 is a diagram illustrating the structure of a next-generation mobile communication system according to an embodiment of the present disclosure.

[0018] FIG. 4 is a diagram illustrating a wireless protocol structure of a next-generation mobile communication system according to an embodiment of the present disclosure.

[0019] FIG. 5 is a block diagram illustrating the internal structure of a terminal according to an embodiment of the present disclosure.

[0020] FIG. 6 is a block diagram showing the configuration of a base station according to one embodiment of the present disclosure.

[0021] FIG. 7 illustrates a procedure for an S-SN (source-secondary node) to create a reference configuration according to an embodiment of the present disclosure.

[0022] FIG. 8a illustrates the structure of a setting configured by each candidate SN according to one embodiment of the present disclosure.

[0023] FIG. 8b illustrates the structure of a master cell group (MCG) part configuration and an MCG reference configuration for each SN configuration according to one embodiment of the present disclosure.

[0024] FIG. 8c illustrates the structure of a target cell setting of SCPAC according to one embodiment of the present disclosure.

[0025] FIG. 9a illustrates a flowchart of a case where one of the candidate SNs is a subject creating an SN reference configuration (i.e., refconfigSCG) according to one embodiment of the present disclosure.

[0026] FIG. 9b illustrates a flowchart of a case where one of the candidate SNs is a subject creating an SN reference configuration (i.e., refconfigSCG) according to one embodiment of the present disclosure.

[0027] FIG. 10 illustrates a process of creating and transmitting a refconfigSCG in the case of an MN-initiated SCPAC according to one embodiment of the present disclosure.

[0028] FIG. 11 illustrates a signal flow diagram when a reference configuration according to an embodiment of the present disclosure is not used.

[0029] FIG. 12a illustrates the structure of a setting configured by each candidate SN when an SN reference configuration according to one embodiment of the present disclosure is not used.

[0030] FIG. 12b illustrates the structure of the MCG part setting and the MCG reference configuration for each SN RRCReconfig when the SN reference configuration according to one embodiment of the present disclosure is not used.

[0031] FIG. 12c illustrates the structure of a target cell setting of SCPAC when an SN reference configuration according to an embodiment of the present disclosure is not used.

[0032] The operating principle of the present disclosure is described in detail with reference to the attached drawings below.

[0033] In the following description of the present disclosure, detailed descriptions of related known functions or configurations will be omitted if they are deemed to unnecessarily obscure the gist of the present disclosure. Furthermore, the terms described below are defined in light of their functions within the present disclosure and may vary depending on the intent or custom of the user or operator. Therefore, their definitions should be based on the overall content of this specification.

[0034] For convenience of explanation, this disclosure uses terms and names defined in the 3rd Generation Partnership Project Long Term Evolution (3GPP) LTE standard. However, this disclosure is not limited to these terms and names and can be equally applied to systems conforming to other standards.

[0035] The advantages and features of the present disclosure, and methods for achieving them, will become clearer with reference to the embodiments described in detail below together with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below and may be implemented in various different forms. These embodiments are provided solely to ensure that the disclosure of the present disclosure is complete and to fully inform those skilled in the art of the scope of the invention, and the present disclosure is defined only by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

[0036] At this time, it will be understood that each block of the processing flowchart drawings and combinations of the flowchart drawings can be performed by computer program instructions. These computer program instructions can be installed in a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing equipment, so that the instructions executed by the processor of the computer or other programmable data processing equipment create a means for performing the functions described in the flowchart block(s). These computer program instructions can also be stored in a computer-available or computer-readable memory that can direct a computer or other programmable data processing equipment to implement the functions in a specific manner, so that the instructions stored in the computer-available or computer-readable memory can also produce a manufactured item that includes an instruction means for performing the functions described in the flowchart block(s). Since the computer program instructions may be installed on a computer or other programmable data processing device, a series of operational steps may be performed on the computer or other programmable data processing device to create a computer-executable process, and the instructions that cause the computer or other programmable data processing device to perform the steps for performing the functions described in the flowchart block(s) may also provide steps for performing the functions described in the flowchart block(s).

[0037] Additionally, each block may represent a module, segment, or portion of code that contains one or more executable instructions for performing a specific logical function(s). It should also be noted that in some alternative implementation examples, the functions described in the blocks may occur out of order. For example, two blocks depicted in succession may actually be executed substantially concurrently, or the blocks may sometimes be executed in reverse order, depending on their respective functions.

[0038] Here, the term '~ part' used in this embodiment means software or hardware components such as FPGA (Field Programmable Gate Array) or ASIC (Application Specific Integrated Circuit), and the '~ part' performs certain roles. However, the '~ part' is not limited to software or hardware. The '~ part' may be configured to be on an addressable storage medium or may be configured to play one or more processors. Therefore, as an example, the '~ part' includes components such as software components, object-oriented software components, class components, and task components, processes, functions, properties, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functions provided within the components and '~ parts' may be combined into a smaller number of components and '~ parts' or further separated into additional components and '~ parts'. Additionally, the components and '~parts' may be implemented to activate one or more CPUs within a device or secure multimedia card. In addition, in an embodiment, the '~parts' may include one or more processors.

[0039] The terms used in the following description to identify connection nodes, terms referring to network entities, terms referring to messages, terms referring to interfaces between network entities, and terms referring to various identification information are provided as examples for convenience of explanation. Therefore, the present disclosure is not limited to the terms described below, and other terms referring to objects with equivalent technical meanings may be used.

[0040] Hereinafter, a base station is an entity that performs resource allocation for a terminal, and may be at least one of a gNode B, an eNode B, a Node B, a BS (Base Station), a wireless access unit, a base station controller, or a node on a network. The terminal may include a UE (User Equipment), an MS (Mobile Station), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing a communication function. Of course, the present invention is not limited to the above examples.

[0041] Wireless communication systems are evolving from providing voice-oriented services in the early days to broadband wireless communication systems that provide high-speed, high-quality packet data services, such as communication standards such as 3GPP's HSPA (High Speed ​​Packet Access), LTE (Long Term Evolution or E-UTRA (Evolved Universal Terrestrial Radio Access)), LTE-Advanced (LTE-A), LTE-Pro, 3GPP2's HRPD (High Rate Packet Data), UMB (Ultra Mobile Broadband), and IEEE's 802.16e.

[0042] As a representative example of a broadband wireless communication system, the LTE system adopts the OFDM (Orthogonal Frequency Division Multiplexing) method in the downlink (DL) and the SC-FDMA (Single Carrier Frequency Division Multiple Access) method in the uplink (UL). The uplink refers to a wireless link in which a terminal (User Equipment; UE or MS; Mobile Station) transmits data or control signals to a base station (eNode B or BS; Base Station), and the downlink refers to a wireless link in which a base station transmits data or control signals to a terminal. The above multiple access method distinguishes the data or control information of each user by allocating and operating the time-frequency resources to be transmitted for each user so that they do not overlap, that is, so as to achieve orthogonality.

[0043] As the future communications system beyond LTE, 5G communication systems must be able to freely reflect the diverse needs of users and service providers. Therefore, they must support services that simultaneously satisfy these diverse requirements. Services being considered for 5G communication systems include Enhanced Mobile Broadband (eMBB), Massive Machine Type Communication (mMTC), and Ultra Reliability Low Latency Communication (URLLC).

[0044] In some embodiments, eMBB may aim to provide data rates that are significantly higher than those supported by existing LTE, LTE-A, or LTE-Pro. For example, in a 5G communication system, eMBB should be able to provide a peak data rate of 20 Gbps in the downlink and a peak data rate of 10 Gbps in the uplink from the perspective of a single base station. Furthermore, a 5G communication system may need to provide both the peak data rate and an increased user-perceived data rate for a terminal. To meet these requirements, a 5G communication system may require improvements in various transmission and reception technologies, including improved multi-input, multi-output (MIMO) transmission technology. Furthermore, while current LTE transmits signals using a maximum 20 MHz transmission bandwidth in the 2 GHz band, a 5G communication system can use a wider frequency bandwidth than 20 MHz in the 3-6 GHz or higher 6 GHz band, thereby meeting the data rates required by the 5G communication system.

[0045] At the same time, mMTC is being considered to support application services such as the Internet of Things (IoT) in 5G communication systems. To efficiently provide the IoT, mMTC may require support for large-scale terminal connections within a cell, improved terminal coverage, improved battery life, and reduced terminal costs. The IoT requires the ability to support a large number of terminals (e.g., 1,000,000 terminals / km2) within a cell, as it provides communication capabilities through the attachment of various sensors and devices. Furthermore, due to the nature of the service, terminals supporting mMTC are likely to be located in shadow areas not covered by cells, such as basements, which may require wider coverage than other services provided by 5G communication systems. Terminals supporting mMTC should be comprised of low-cost terminals, and since frequent battery replacement is unlikely, extremely long battery lifespans, such as 10 to 15 years, may be required.

[0046] Finally, URLLC is a cellular-based wireless communication service used for specific purposes (mission-critical), such as remote control of robots or machinery, industrial automation, unmanned aerial vehicles (UAVs), remote health care, and emergency alerts. Therefore, the communication provided by URLLC may need to provide very low latency (ultra-low latency) and very high reliability (ultra-reliability). For example, a service supporting URLLC may have to satisfy an air interface latency of less than 0.5 milliseconds and may also have a requirement for a packet error rate (PER) of 10-5 or less. Therefore, for services supporting URLLC, 5G systems may be required to provide a smaller Transmit Time Interval (TTI) than other services, while simultaneously allocating a wide range of resources in the frequency band to ensure the reliability of the communication link.

[0047] The three services considered in the aforementioned 5G communication system—eMBB, URLLC, and mMTC—can be multiplexed and transmitted in a single system. To meet the differing requirements of each service, different transmission and reception techniques and parameters may be used between the services. However, the aforementioned mMTC, URLLC, and eMBB are merely examples of different service types, and the service types applicable to this disclosure are not limited to the aforementioned examples.

[0048] Furthermore, while embodiments of the present invention will be described below using LTE, LTE-A, LTE Pro, or 5G (or NR, next-generation mobile communication) systems as examples, the embodiments of the present invention may also be applied to other communication systems with similar technical backgrounds or channel types. Furthermore, embodiments of the present invention may be applied to other communication systems with some modifications, as determined by a person skilled in the art, without significantly departing from the scope of the present invention.

[0049] FIG. 1 is a diagram illustrating the structure of an LTE system according to one embodiment of the present disclosure.

[0050] Referring to FIG. 1, as illustrated, a wireless access network of an LTE system may be composed of next-generation base stations (Evolved Node Bs, hereinafter referred to as ENBs, Node Bs or base stations) (1-05, 1-10, 1-15, 1-20), a mobility management entity (MME) (1-25) and an S-GW (1-30, Serving-Gateway). A user equipment (UE or terminal) (1-35) may access an external network through the ENBs (1-05 to 1-20) and the S-GW (1-30).

[0051] In Fig. 1, ENBs (1-05 to 1-20) may correspond to existing Node Bs of a UMTS system. ENBs are connected to UEs (1-35) via a wireless channel and may perform a more complex role than existing Node Bs. In an LTE system, all user traffic, including real-time services such as Voice over IP (VoIP) via the Internet Protocol, may be serviced through a shared channel. Therefore, a device that collects status information such as buffer status, available transmission power status, and channel status of UEs and performs scheduling may be required, and ENBs (1-05 to 1-20) may be responsible for this. One ENB can typically control multiple cells. For example, to achieve a transmission rate of 100 Mbps, an LTE system may use, for example, Orthogonal Frequency Division Multiplexing (OFDM) as a wireless access technology in a 20 MHz bandwidth. Additionally, the ENB can apply an Adaptive Modulation & Coding (AMC) method that determines the modulation scheme and channel coding rate according to the channel condition of the terminal. The S-GW (1-30) is a device that provides a data bearer and can create or remove a data bearer under the control of the MME (1-25). The MME is a device that is responsible for various control functions as well as mobility management functions for the terminal and can be connected to multiple base stations.

[0052] FIG. 2 is a diagram illustrating a wireless protocol structure of an LTE system according to an embodiment of the present disclosure.

[0053] Referring to FIG. 2, the wireless protocol of the LTE system may include Packet Data Convergence Protocol (PDCP) (2-05, 2-40), Radio Link Control (RLC) (2-10, 2-35), Medium Access Control (MAC) (2-15, 2-30), and Physical Layer (2-20, 2-25) in the terminal and ENB, respectively. PDCP may be responsible for operations such as IP header compression / decompression. The main functions of PDCP can be summarized as follows. Of course, the present invention is not limited to the following examples.

[0054] - Header compression and decompression (ROHC only)

[0055] - User data transfer function

[0056] - In-sequence delivery of upper layer PDUs at PDCP re-establishment procedure for RLC AM

[0057] - Order reordering function (For split bearers in DC (only support for RLC AM): PDCP PDU routing for transmission and PDCP PDU reordering for reception)

[0058] - Duplicate detection function (Duplicate detection of lower layer SDUs at PDCP re-establishment procedure for RLC AM)

[0059] - Retransmission function (Retransmission of PDCP SDUs at handover and, for split bearers in DC, of ​​PDCP PDUs at PDCP data-recovery procedure, for RLC AM)

[0060] - Encryption and decryption functions (Ciphering and deciphering)

[0061] - Timer-based SDU discard in uplink.

[0062] In some embodiments, Radio Link Control (RLC) (2-10, 2-35) may reconfigure PDCP Packet Data Units (PDUs) to an appropriate size to perform ARQ operations, etc. The main functions of RLC can be summarized as follows. Of course, the present invention is not limited to the following examples.

[0063] - Data transfer function (Transfer of upper layer PDUs)

[0064] - ARQ function (Error Correction through ARQ (only for AM data transfer))

[0065] - Concatenation, segmentation and reassembly of RLC SDUs (only for UM and AM data transfer)

[0066] - Re-segmentation of RLC data PDUs (only for AM data transfer)

[0067] - Reordering of RLC data PDUs (only for UM and AM data transfer)

[0068] - Duplicate detection (only for UM and AM data transfer)

[0069] - Error detection function (Protocol error detection (only for AM data transfer))

[0070] - RLC SDU discard function (RLC SDU discard (only for UM and AM data transfer))

[0071] - RLC re-establishment function

[0072] In some embodiments, the MAC (2-15, 2-30) is connected to multiple RLC layer devices configured in a single terminal, and can perform operations of multiplexing RLC PDUs into MAC PDUs and demultiplexing RLC PDUs from MAC PDUs. The main functions of the MAC can be summarized as follows. Of course, the present invention is not limited to the following examples.

[0073] - Mapping function (Mapping between logical channels and transport channels)

[0074] - Multiplexing and demultiplexing function (Multiplexing / demultiplexing of MAC SDUs belonging to one or different logical channels into / from transport blocks (TB) delivered to / from the physical layer on transport channels)

[0075] - Scheduling information reporting function

[0076] - HARQ function (Error correction through HARQ)

[0077] - Priority handling between logical channels of one UE

[0078] - Priority handling between UEs by means of dynamic scheduling

[0079] - MBMS service identification function

[0080] - Transport format selection function

[0081] - Padding function

[0082] In some embodiments, the physical layer (2-20, 2-25) may perform an operation of channel coding and modulating upper layer data, converting it into OFDM symbols and transmitting it over a wireless channel, or demodulating and channel decoding OFDM symbols received over a wireless channel and transmitting them to a higher layer. Of course, the present invention is not limited to the following examples.

[0083] FIG. 3 is a diagram illustrating the structure of a next-generation mobile communication system according to an embodiment of the present disclosure.

[0084] Referring to FIG. 3, a wireless access network of a next-generation mobile communication system (hereinafter referred to as NR or 5g) may be composed of a next-generation base station (New Radio Node B, hereinafter referred to as NR gNB or NR base station) (3-10) and a next-generation radio core network (New Radio Core Network, NR CN) (3-05). A next-generation radio user equipment (New Radio User Equipment, NR UE or terminal) (3-15) may access an external network through the NR gNB (3-10) and the NR CN (3-05).

[0085] In Fig. 3, the NR gNB (3-10) may correspond to the eNB (Evolved Node B) of the existing LTE system. The NR gNB is connected to the NR UE (3-15) via a wireless channel and can provide superior services than the existing Node B. In the next-generation mobile communication system, all user traffic can be serviced through a shared channel. Therefore, a device that collects status information such as the buffer status of UEs, available transmission power status, and channel status and performs scheduling may be required, and the NR NB (3-10) can be in charge of this. A single NR gNB can control multiple cells. In the next-generation mobile communication system, in order to implement ultra-high-speed data transmission compared to the current LTE, a bandwidth greater than the current maximum bandwidth may be applied. In addition, beamforming technology may be additionally used by using Orthogonal Frequency Division Multiplexing (OFDM) as a wireless access technology.

[0086] In addition, according to some embodiments, the NR gNB may apply an adaptive modulation and coding (AMC) method that determines a modulation scheme and a channel coding rate according to the channel condition of the terminal. The NR CN (3-05) may perform functions such as mobility support, bearer setup, and QoS setup. The NR CN (3-05) is a device that is responsible for various control functions as well as mobility management functions for the terminal and may be connected to multiple base stations. In addition, the next-generation mobile communication system may also be interoperable with the existing LTE system, and the NR CN may be connected to the MME (3-25) through a network interface. The MME may be connected to the existing base station, eNB (3-30).

[0087] FIG. 4 is a diagram illustrating a wireless protocol structure of a next-generation mobile communication system according to an embodiment of the present disclosure.

[0088] Referring to FIG. 4, the wireless protocol of the next-generation mobile communication system may include NR Service Data Adaptation Protocol (SDAP) (4-01, 4-45), NR PDCP (4-05, 4-40), NR RLC (4-10, 4-35), NR MAC (4-15, 4-30), and NR PHY layer (4-20, 4-25) in the terminal and NR base station, respectively.

[0089] According to some embodiments, the main functions of NR SDAP (4-01, 4-45) may include some of the following functions, but are not limited to the examples below.

[0090] - Transfer of user plane data

[0091] - Mapping function between QoS flow and data bearer for both DL and UL

[0092] - QoS flow ID marking function for uplink and downlink (marking QoS flow ID in both DL and UL packets)

[0093] - Ability to map relective QoS flow to data bearer for uplink SDAP PDUs (reflective QoS flow to DRB mapping for the UL SDAP PDUs).

[0094] For an SDAP layer device, a terminal can be configured by a Radio Resource Control (RRC) message for each PDCP layer device, by bearer, or by logical channel, whether to use the header of the SDAP layer device or whether to use the function of the SDAP layer device. In addition, when the SDAP header is configured, the SDAP layer device can instruct the terminal to update or reset the mapping information for the QoS flow and data bearer of the uplink and downlink using a 1-bit indicator for reflecting the Non-Access Stratum (NAS) Quality of Service (QoS) in the SDAP header (NAS reflective QoS) and a 1-bit indicator for reflecting the Access Stratum (AS) QoS in the SDAP header. In some embodiments, the SDAP header may include QoS flow ID information indicating the QoS. In some embodiments, the QoS information may be used as data processing priority, scheduling information, etc. to support a smooth service.

[0095] According to some embodiments, the main functions of NR PDCP (4-05, 4-40) may include some of the following functions, but are not limited to the examples below.

[0096] - Header compression and decompression (ROHC only)

[0097] - User data transfer function

[0098] - In-sequence delivery of upper layer PDUs

[0099] - Out-of-sequence delivery of upper layer PDUs

[0100] - PDCP PDU reordering for reception

[0101] - Duplicate detection of lower layer SDUs

[0102] - Retransmission function (Retransmission of PDCP SDUs)

[0103] - Encryption and decryption functions (Ciphering and deciphering)

[0104] - Timer-based SDU discard in uplink.

[0105] In the above, the reordering function of the NR PDCP device may refer to a function of reordering PDCP PDUs received from a lower layer in order based on the PDCP sequence number. The reordering function of the NR PDCP device may include a function of transmitting data to an upper layer in the reordered order, or a function of transmitting data directly without considering the order, a function of recording lost PDCP PDUs by reordering the order, a function of reporting a status of lost PDCP PDUs to the transmitting side, and a function of requesting retransmission of lost PDCP PDUs.

[0106] According to some embodiments, the main functions of the NR RLC (4-10, 4-35) may include some of the following functions, but are not limited to the examples below.

[0107] - Data transfer function (Transfer of upper layer PDUs)

[0108] - In-sequence delivery of upper layer PDUs

[0109] - Out-of-sequence delivery of upper layer PDUs

[0110] - ARQ function (Error Correction through ARQ)

[0111] - Concatenation, segmentation and reassembly of RLC SDUs

[0112] - Re-segmentation of RLC data PDUs

[0113] - Reordering of RLC data PDUs

[0114] - Duplicate detection function

[0115] - Protocol error detection

[0116] - RLC SDU discard function

[0117] - RLC re-establishment function

[0118] In the above, the in-sequence delivery function of the NR RLC device may refer to the function of sequentially delivering RLC SDUs received from the lower layer to the upper layer. If a single RLC SDU is originally received divided into multiple RLC SDUs, the in-sequence delivery function of the NR RLC device may include the function of reassembling and delivering them.

[0119] The in-sequence delivery function of the NR RLC device may include a function to reorder received RLC PDUs based on the RLC sequence number or PDCP sequence number, a function to record lost RLC PDUs by reordering them, a function to report status of lost RLC PDUs to the transmitter, and a function to request retransmission of lost RLC PDUs.

[0120] The in-sequence delivery function of the NR RLC device may include a function to sequentially deliver only the RLC SDUs up to the lost RLC SDU to the upper layer when there is a lost RLC SDU.

[0121] The in-sequence delivery function of the NR RLC device may include a function to deliver to the upper layer in sequence all RLC SDUs received before a predetermined timer starts if there are lost RLC SDUs and a predetermined timer has expired.

[0122] The in-sequence delivery function of the NR RLC device may include a function to deliver all RLC SDUs received so far to the upper layer in order if a predetermined timer has expired, even if there are lost RLC SDUs.

[0123] An NR RLC device can process RLC PDUs in the order they are received and deliver them to an NR PDCP device, regardless of the order of the sequence number (out-of-sequence delivery).

[0124] When an NR RLC device receives a segment, it can receive segments that are stored in a buffer or will be received later, reconstruct them into a complete RLC PDU, and then transmit them to the NR PDCP device.

[0125] The NR RLC layer may not include concatenation functionality, and the functionality may be performed by the NR MAC layer or replaced by the multiplexing functionality of the NR MAC layer.

[0126] In the above, the out-of-sequence delivery function of the NR RLC device may refer to the function of directly delivering RLC SDUs received from a lower layer to an upper layer regardless of the order. The out-of-sequence delivery function of the NR RLC device may include the function of reassembling and delivering multiple RLC SDUs when an original RLC SDU is received fragmented into multiple RLC SDUs. The out-of-sequence delivery function of the NR RLC device may include the function of storing and arranging the RLC sequence numbers or PDCP sequence numbers of received RLC PDUs to record any lost RLC PDUs.

[0127] In some embodiments, the NR MAC (4-15, 4-30) may be connected to multiple NR RLC layer devices configured in one terminal, and the main functions of the NR MAC may include some of the following functions, but are not limited to the examples below.

[0128] - Mapping function (Mapping between logical channels and transport channels)

[0129] - Multiplexing / demultiplexing of MAC SDUs

[0130] - Scheduling information reporting function

[0131] - HARQ function (Error correction through HARQ)

[0132] - Priority handling between logical channels of one UE

[0133] - Priority handling between UEs by means of dynamic scheduling

[0134] - MBMS service identification function

[0135] - Transport format selection function

[0136] - Padding function

[0137] The NR PHY layer (4-20, 4-25) can perform operations such as channel coding and modulating upper layer data, converting it into OFDM symbols and transmitting it through a wireless channel, or demodulating and channel decoding OFDM symbols received through a wireless channel and transmitting them to a higher layer.

[0138] FIG. 5 is a block diagram illustrating the internal structure of a terminal according to an embodiment of the present disclosure.

[0139] Referring to FIG. 5, the terminal may include an RF (Radio Frequency) processing unit (5-10), a baseband processing unit (5-20), a storage unit (5-30), and a control unit (5-40). Of course, the present invention is not limited to the above example, and the terminal may include fewer or more components than the configuration illustrated in FIG. 5.

[0140] The RF processing unit (5-10) can perform functions for transmitting and receiving signals through a wireless channel, such as signal band conversion and amplification. That is, the RF processing unit (5-10) can up-convert a baseband signal provided from the baseband processing unit (5-20) into an RF band signal and transmit it through an antenna, and down-convert an RF band signal received through the antenna into a baseband signal. For example, the RF processing unit (5-10) can include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a digital to analog convertor (DAC), an analog to digital convertor (ADC), etc. Of course, it is not limited to the above example. In Fig. 5, only one antenna is illustrated, but the terminal can be equipped with multiple antennas. In addition, the RF processing unit (5-10) can include multiple RF chains. In addition, the RF processing unit (5-10) can perform beamforming. For beamforming, the RF processing unit (5-10) can adjust the phase and magnitude of each signal transmitted and received through multiple antennas or antenna elements. In addition, the RF processing unit (5-10) can perform MIMO (Multi Input Multi Output) and can receive multiple layers when performing MIMO operation.

[0141] The baseband processing unit (5-20) performs a conversion function between baseband signals and bit streams according to the physical layer specifications of the system. For example, when transmitting data, the baseband processing unit (5-20) generates complex symbols by encoding and modulating the transmission bit stream. In addition, when receiving data, the baseband processing unit (5-20) can restore the reception bit stream by demodulating and decoding the baseband signal provided from the RF processing unit (5-10). For example, in the case of OFDM (orthogonal frequency division multiplexing), when transmitting data, the baseband processing unit (5-20) generates complex symbols by encoding and modulating the transmission bit stream, maps the complex symbols to subcarriers, and then configures OFDM symbols by performing an inverse fast Fourier transform (IFFT) operation and inserting a cyclic prefix (CP). In addition, when receiving data, the baseband processing unit (5-20) divides the baseband signal provided from the RF processing unit (5-10) into OFDM symbol units, restores signals mapped to subcarriers through FFT (fast Fourier transform), and then restores the received bit string through demodulation and decoding.

[0142] The baseband processing unit (5-20) and the RF processing unit (5-10) transmit and receive signals as described above. The baseband processing unit (5-20) and the RF processing unit (5-10) may be referred to as a transmitter, a receiver, a transceiver, or a communication unit. Furthermore, at least one of the baseband processing unit (5-20) and the RF processing unit (5-10) may include a plurality of communication modules to support a plurality of different wireless access technologies. In addition, at least one of the baseband processing unit (5-20) and the RF processing unit (5-10) may include different communication modules to process signals of different frequency bands. For example, the different wireless access technologies may include wireless LAN (e.g., IEEE 802.11), a cellular network (e.g., LTE), etc. In addition, the different frequency bands may include a super high frequency (SHF) (e.g., 2.NRHz, NRhz) band and a millimeter wave (mm wave) (e.g., 60GHz) band. The terminal may transmit and receive signals with the base station using the baseband processing unit (5-20) and the RF processing unit (5-10), and the signals may include control information and data.

[0143] The storage unit (5-30) stores data such as basic programs, application programs, and setting information for the operation of the terminal. In particular, the storage unit (5-30) can store information related to a second access node that performs wireless communication using a second wireless access technology. In addition, the storage unit (5-30) provides the stored data upon request from the control unit (5-40). The storage unit (5-30) may be configured as a storage medium such as a ROM, a RAM, a hard disk, a CD-ROM, and a DVD, or a combination of storage media. In addition, the storage unit (5-30) may be configured as a plurality of memories.

[0144] The control unit (5-40) controls the overall operations of the terminal. For example, the control unit (5-40) transmits and receives signals through the baseband processing unit (5-20) and the RF processing unit (5-10). In addition, the control unit (5-40) records and reads data in the storage unit (5-40). For this purpose, the control unit (5-40) may include at least one processor. For example, the control unit (5-40) may include a communication processor (CP) that performs control for communication and an application processor (AP) that controls upper layers such as application programs. In addition, at least one component within the terminal may be implemented as a single chip. For example, the control unit (5-40) may further include a multi-connection processing unit (5-42).

[0145] FIG. 6 is a block diagram showing the configuration of a base station according to one embodiment of the present disclosure.

[0146] Referring to FIG. 6, the base station may include an RF processing unit (6-10), a baseband processing unit (6-20), a backhaul communication unit (6-30), a storage unit (6-40), and a control unit (6-50). Of course, the present invention is not limited to the above example, and the base station may include fewer or more components than the configuration illustrated in FIG. 6.

[0147] The RF processing unit (6-10) can perform functions for transmitting and receiving signals through a wireless channel, such as signal band conversion and amplification. That is, the RF processing unit (6-10) up-converts the baseband signal provided from the baseband processing unit (6-20) into an RF band signal and transmits it through an antenna, and down-converts the RF band signal received through the antenna into a baseband signal. For example, the RF processing unit (6-10) may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, etc. In Fig. 6, only one antenna is illustrated, but the RF processing unit (6-10) may be equipped with multiple antennas. In addition, the RF processing unit (6-10) may include multiple RF chains. In addition, the RF processing unit (6-10) may perform beamforming. For beamforming, the RF processing unit (6-10) may adjust the phase and magnitude of each signal transmitted and received through multiple antennas or antenna elements. The RF processing unit can perform downlink MIMO operations by transmitting one or more layers.

[0148] The baseband processing unit (6-20) can perform a conversion function between a baseband signal and a bit stream according to the physical layer specifications of the first wireless access technology. For example, when transmitting data, the baseband processing unit (6-20) can generate complex symbols by encoding and modulating a transmission bit stream. In addition, when receiving data, the baseband processing unit (6-20) can restore the reception bit stream by demodulating and decoding the baseband signal provided from the RF processing unit (6-10). For example, in the case of OFDM, when transmitting data, the baseband processing unit (6-20) generates complex symbols by encoding and modulating a transmission bit stream, maps the complex symbols to subcarriers, and then configures OFDM symbols through IFFT operation and CP insertion. In addition, when receiving data, the baseband processing unit (6-20) can divide the baseband signal provided from the RF processing unit (6-10) into OFDM symbol units, restore the signals mapped to subcarriers through FFT operation, and then restore the received bit string through demodulation and decoding. The baseband processing unit (6-20) and the RF processing unit (6-10) can transmit and receive signals as described above. Accordingly, the baseband processing unit (6-20) and the RF processing unit (6-10) may be referred to as a transmitting unit, a receiving unit, a transceiver unit, a communication unit, or a wireless communication unit. The base station can transmit and receive signals with the terminal using the baseband processing unit (6-20) and the RF processing unit (6-10), and the signals may include control information and data.

[0149] The backhaul communication unit (6-30) provides an interface for communicating with other nodes within the network. That is, the backhaul communication unit (6-30) can convert bit streams transmitted from the primary base station to other nodes, such as auxiliary base stations and core networks, into physical signals, and can also convert physical signals received from other nodes into bit streams. The backhaul communication unit (6-30) may also be included in the communication unit.

[0150] The storage unit (6-40) stores data such as basic programs, application programs, and setting information for the operation of the base station. The storage unit (6-40) can store information on bearers assigned to connected terminals, measurement results reported from connected terminals, etc. In addition, the storage unit (6-40) can store information that serves as a basis for determining whether to provide or terminate multiple connections to the terminals. In addition, the storage unit (6-40) provides the stored data upon request of the control unit (6-50). The storage unit (6-40) can be configured as a storage medium or a combination of storage media such as a ROM, a RAM, a hard disk, a CD-ROM, and a DVD. In addition, the storage unit (6-40) can be configured as a plurality of memories. In some embodiments, the storage unit (6-40) can also store a program for performing a buffer status reporting method according to the present disclosure.

[0151] The control unit (6-50) controls the overall operations of the base station. For example, the control unit (6-50) transmits and receives signals through the baseband processing unit (6-20) and the RF processing unit (6-10) or through the backhaul communication unit (6-30). In addition, the control unit (6-50) records and reads data in the storage unit (6-40). For this purpose, the control unit (6-50) may include at least one processor. In addition, at least one component of the base station may be implemented in a single chip. For example, the control unit (6-50) may further include a multi-connection processing unit (6-52).

[0152] Regarding the configuration for subsequent conditional PSCell addition or change (SCPAC), there was a discussion after RAN2#123bis whether the UE should follow the full configuration procedure specified in 5.3.5.11 of TS 38.331 or a new complete configuration procedure when applying a complete configuration.

[0153] Currently, the operation in the known phase may include a condReconfigId (this field is used to identify a CHO (conditional handover), CPA (conditional PSCell addition) or CPC (conditional PSCell change) configuration among the configurations passed to the conditional reconfiguration field set to the terminal (this field is used to add, modify and release the configuration of the conditional reconfiguration). Among the condReconfigId, the condRRCReconfig of an entry with SCPAC configuration (condRRCReconfig indicates an RRCReconfiguration message to be applied when the condition is satisfied) is a delta configuration for combining with a reference configuration, and when SCPAC is triggered, a complete configuration to be applied by the terminal may be composed of a combination of the reference configuration and the delta configuration.

[0154] In this regard, the present disclosure proposes which nodes create the reference configuration and the delta configuration. In addition, the present disclosure proposes a method for combining the reference configuration and the delta configuration to form a complete configuration, and a method for a terminal to apply the final complete configuration.

[0155] The complete configuration to be applied to the terminal is different from the existing RRCReconfiguration application or the CHO / CPAC target cell application method. The existing application method was to add the additional RRCReconfiguration in delta format on top of the current terminal configuration. In contrast, the SCPAC configuration can be done by ignoring all configuration information of the current terminal or releasing / clearing it, and overwriting the complete configuration by adding the target cell configuration given for each target cell in delta format to a separately provided reference configuration.

[0156] According to the above definition, a terminal can ultimately configure a complete configuration based on a single reference configuration and a corresponding delta configuration for each target cell in relation to SCPAC. Therefore, the network can provide the terminal with a reference configuration and delta configurations for multiple target cells.

[0157] In relation to SCPAC, the entity that creates the secondary node (SN) reference configuration must be the SN. Accordingly, during the SCPAC setup preparation operation, either the source SN (S-SN) or any candidate SN can create the reference configuration.

[0158] For example, the SN part of the SCPAC reference setting can be created from S-SN.

[0159] Alternatively, after transmitting the initial SCPAC settings to the terminal, the candidate SN may create the SN portion of the SCPAC reference settings, if necessary.

[0160] In each case, a new X2 signal is required.

[0161] However, since all candidate SNs must be able to obtain the same reference configuration in the inter-node signaling procedure, it may be desirable for the S-SN, which has already defined the information transfer procedure through the master node (MN), to create the reference configuration at least during the initial SCPAC setup preparation stage.

[0162] FIG. 7 illustrates a flowchart of a case in which an S-SN creates a reference configuration according to an embodiment of the present disclosure.

[0163] Referring to FIG. 7, at step 710, the S-SN (e.g., SN1) may transmit an SN change required message to the MN. The SN change required message may include an indicator indicating the start of SCPAC, a list of candidate SNs for SCPAC, a list of candidate PSCells suggested to be prepared by each candidate SN, and / or information on a migration condition for each proposed candidate target PSCell based on the source PSCell (an execution condition associated with each suggested PSCell). In addition, the S-SN may create and include an SN reference configuration (e.g., refconfigSCG) in the SN change required message.

[0164] In step 720, the MN can send an SN addition request message (e.g., SNAddReq) to each of the candidate SNs (e.g., SN2, SN3). The MN can convey information about candidate PSCells received from the S-SN to each of the candidate SNs (e.g., SN2, SN3) through the SN addition request message. In addition, information about candidate PSCells recommended by the S-SN among candidate PSCells of other candidate SNs can also be conveyed through the SN addition request message. At this time, the MN can include the SN reference configuration (e.g., refConfigSCG) received from the S-SN in the SN addition request message and convey it.

[0165] In step 730, each candidate SN may perform admission control among the recommended candidate PSCells corresponding to itself received from the MN, determine a prepared PSCell (or admitted PSCell candidate), and determine a target configuration to be used in the corresponding cell (i.e., prepared PSCell). Each candidate SN may transmit an SN addition request acknowledge message (e.g., SNAddReqACK) to the MN, which includes information about the prepared PSCell and the target configuration to be used in the corresponding cell.

[0166] Additionally, each candidate SN may include condition information to be used for moving from one of the prepared PSCells to a recommended candidate PSCell of another candidate SN and / or another cell among its own prepared PSCells in an SN addition request acknowledge message (e.g., SNAddReqACK message) and transmit it to the MN. Among these, each candidate SN may also write a condition for moving from the corresponding cell to a candidate PSCell of another candidate SN. At this time, each candidate SN may accept or reject the movement from its own prepared PSCell to a candidate PSCell of a specific candidate SN. If it accepts, the condition information for moving from its own prepared PSCell to a candidate PSCell of a specific candidate SN is added to the SN addition request acknowledge message, and if it rejects, the condition information may not be included in the SN addition request acknowledge message.

[0167] Here, the target configuration to be used in the corresponding cell (i.e., prepared PSCell) may mean the delta configuration of the SN part based on the reference configuration transmitted from the MN. The configuration of each candidate SN transmitted from A corresponding to step 730 (e.g., SN RRCReconfig) may have the structure of Fig. 8a.

[0168] In step 740, the MN can receive the above information from each candidate SN and check whether there is a PSCell among the recommended PSCells that failed to be prepared in the SN based on the above information. If not all the recommended PSCells are prepared in each candidate SN (e.g., if there is no information about prepared PSCells in the message received in step 730), the information about the PSCells that failed to be prepared can be re-transmitted to each candidate SN and S-SN. At this time, an SN modification request message (e.g., SNModReq) can be used as the message.

[0169] Upon receiving an SN modification request (e.g., SNModReq) message, each candidate SN and S-SN updates the condition information considering only the prepared (i.e., admitted) PSCells from the candidate PSCells recommended to it (i.e., if conditions for all candidate PSCells were previously created, some of them are removed), and updates the measurement configuration including the condition information (i.e., for the combination of MO (measurement object) and reportconfig for the conditions of all candidate PSCells previously, some are removed, leaving only those for prepared candidate cells), so that the target cell configuration including the conditions and measurement configuration for only admitted (prepared) PSCells can be transmitted to the MN via an SN modification request acknowledge (e.g., SNModReqACK) message.

[0170] At step 750, the MN may receive an SN modification request acknowledge (e.g., SNModReqACK).

[0171] In step 760, the MN can configure the SN RRCReconfig, i.e., the SCG configuration, using the SN reference configuration (e.g., refconfigSCG) received from the S-SN and the delta configuration of the candidate PSCell created by each candidate SN. Based on this configuration information, the MN can configure the master cell group (MCG) configuration (i.e., the MCG part configuration for each SN RRCReconfig, a part of the RRCReconfiguration in the MN format) (B-1). The RRCReconfiguration in the MN format, which is a combination of the MCG configuration and the SCG configuration, can be called a complete configuration. In addition, the MN can create multiple MCG configurations corresponding to the SCG configurations for multiple PSCells, and based on this, the MN can create an MCG reference configuration (or named refConfigMCG) having common parameters among the multiple MCG configurations (B-2). The above MCG configuration and the above MCG reference configuration may have the structure of FIG. 8b.

[0172] Finally, the MN can assign / map condition information and target cell configuration information for target PSCells to the condReconfig Id and transmit them to the UE. At this time, SCPAC settings can be added (additionally mapped) to each condReconfig Id.

[0173] In addition, the MN can combine the refconfigSCG received from the S-SN and the refConfigMCG created by the MN and transmit it to the UE as a reference configuration. In addition, as a configuration of each candidate PSCell, the RRCReconfiguration in the MN format excluding the refconfigMCG and refconfigSCG from the complete configuration created in the previous (B-2) can be created as a target cell configuration of SCPAC for each target PSCell and transmitted to the UE by mapping it with each condReconfig id (C). The target cell configuration (C) of the SCPAC can have the structure of FIG. 8c. The information transmitted from the MN to the UE can be transmitted to the UE through an RRC reconfiguration message in step 770. In step 780, the UE can transmit an RRC reconfiguration complete message to the MN.

[0174] In step 790, the terminal that received the above information can perform condition evaluation. If the condition for SCPAC (e.g., one of the conditions of SCPAC config) is satisfied, the terminal can create a final complete configuration by adding a delta configuration to the given reference configuration of the target cell. If the condition for SCPAC is satisfied, the terminal can execute SCPAC for the target PSCell. The terminal applies this complete configuration when executing SCPAC, but in this case (if the complete configuration is created using the reference configuration), the full configuration mentioned later can be applied.

[0175] The terminal may transmit an RRC reconfiguration complete message to the MN. The RRC reconfiguration complete message may include triggered PSCell information.

[0176] FIG. 8a illustrates the structure of a setting configured by each candidate SN according to one embodiment of the present disclosure.

[0177] Referring to FIG. 8a, SN RRCReconfig may include a referenceconfigSCG and one deltaConfigSCG.

[0178] FIG. 8b illustrates the structure of MCG part settings and MCG reference configuration for each SN RRCReconfig according to one embodiment of the present disclosure.

[0179] Referring to Fig. 8b, the MN can create an MCG part configuration for each SN RRCReconfig (i.e., a part of the RRCReconfiguration in the MN format, called MCG configuration). The MN can create an MCG reference configuration (i.e., refconfigMCG) based on the MCG part configurations.

[0180] FIG. 8c illustrates the structure of a target cell setting of SCPAC according to one embodiment of the present disclosure.

[0181] The MN can compile the remaining MCG / SCG deltaconfigs, excluding the MCG ref (refconfigMCG) and SCG ref (refconfigSCG), to create the final candidate PSCell config (condRRCReconfig for SCPAC) and configure it for the UE. At this time, the MN can also transmit the SCPAC reference configuration to the UE.

[0182] FIG. 9a and FIG. 9b illustrate a flowchart of a case where one of the candidate SNs is a subject of creating an SN reference configuration (i.e., refconfigSCG) according to an embodiment of the present disclosure.

[0183] The description of steps 9010 to 9064 of FIG. 9a may refer to the description of steps 710 to 780 of FIG. 7. Therefore, for the convenience of explanation, redundant content will be omitted.

[0184] Referring to FIGS. 9a and 9b, after SCPAC preparation is completed and the configuration is transmitted to the terminal as in FIG. 7, a message including an indicator requesting a change in the reference configuration and a changed refconfigSCG (e.g., an SN change required message or an SN modification required message) can be transmitted to the MN by one of the candidate SNs. Although FIGS. 9a and 9b illustrate an example in which SN2 transmits an SN change required message (or an SN modification required message) to the MN at step 9070, it is also possible for another candidate SN to transmit the message.

[0185] At step 9080, the MN may send a message (e.g., SN change request message or SN modification request message) containing the changed (new) refconfigSCG to the S-SN.

[0186] If S-SN accepts the change request, SN change / modification procedure can be followed.

[0187] Steps 9090 and 9100 of FIGS. 9A and 9B may correspond to steps 9020 and 9030, except that they are based on a new refconfigSCG. Furthermore, steps 9110 and 9120 of FIGS. 9A and 9B may correspond to steps 9040 and 9050, except that they are based on a new refconfigSCG. Furthermore, step 9130 of FIGS. 9A and 9B may correspond to step 9060, except that they are based on a new refconfigSCG. Furthermore, steps 9140 and 9150 of FIGS. 9A and 9B may correspond to steps 9062 and 9064. Therefore, the descriptions of the corresponding steps in FIGS. 7 and 9A and 9B may be referred to in steps 9090 to 9150.

[0188] FIG. 10 illustrates a process of creating and transmitting refconfigSCG in the case of MN-initiated SCPAC according to one embodiment of the present disclosure.

[0189] In one embodiment, when an MN creates a refconfigSCG, the MN may create the refconfigSCG based on background knowledge about the SCG configuration previously obtained through inter-node signaling with the S-SN. In this case, the MN may include the refconfigSCG when requesting SCPAC configuration to each candidate SN through an SN Add Request message (SNAddReq message).

[0190] Each candidate SN that receives the SNAddReq message will operate in the same manner as in FIG. 7. Steps 1020 to 1090 of FIG. 10 may correspond to steps 720 to 790 of FIG. 7. Therefore, the description of FIG. 7 may be referred to, and any overlapping content will be omitted for convenience of explanation.

[0191] In another embodiment, it is also possible for the S-SN to still create the refconfigSCG. In this case, the MN may request a trigger for SCPAC setup from the SN in step 1005, and thereafter, the SN-initiated SCPAC setup preparation operations described in FIG. 7 may be performed. In this case, in preparation for the procedure in which the MN creates the refconfigSCG, the *SN SCPAC trigger operation (step 1005) and the *SN change required message transmission (step 1010) procedures, indicated by * in FIG. 10, may be added. Compared to the SN-initiated process illustrated in FIG. 7, the *SN SCPAC trigger message is transmitted from the MN to the S-SN (step 1005), thereby causing the S-SN to perform the SN-initiated SCPAC procedure.

[0192] In the operations of FIGS. 7 to 10, the terminal can consequently be set to a target cell configuration corresponding to a ref configuration and a delta configuration based on each target cell.

[0193] When SCPAC requires specific conditions to be met and SCPAC is to be performed, the terminal can first create a complete configuration by combining the delta configuration of the target cell for which the conditions are met with the given reference configuration. Then, the terminal can clear / release the configuration information of its serving cell and apply the complete configuration.

[0194] During the above process, the process of clearing / releasing the configuration information of the serving cell may follow the existing full configuration procedure, or the procedure may be included in the SCPAC execution process.

[0195] For example, it describes the process of clearing / releasing the configuration information of a serving cell by following the existing full configuration procedure.

[0196] Previously, the fullConfig directive could not be used when applying SN RRCReconfig. Even in Release 17 CPAC, the fullConfig directive was not included when applying MN RRCReconfig (NW implementation). Furthermore, the fullconfig section itself contained only the MCG reconfigurationWithSync condition.

[0197] However, SCPAC should be able to perform full configuration operations even if only SCG's reconfigurationWithSync is present. To achieve this, the fullConfig directive can always be set in the final SCPAC configuration. The fullConfig directive can be included in the MCG part configuration or refconfigMCG, or in the SCG part configuration or refconfigSCG. A terminal that receives the directive can perform the corresponding full configuration procedure.

[0198] In another case, the fullconfig directive can be included inside the SCPAC execution procedure even if it does not exist in the target configuration.

[0199] (Option 1: NW (network) explicitly indicates fullconfig directive, and UE can apply full configuration including fullconfig directive. MN can always add fullconfig directive to SCPAC base configuration or each delta candidate configuration for SCPAC.

[0200] Option 2: No NW directive, but SCPAC execution section can implicitly include full config operation without specific part / section)

[0201] Additionally, the full configuration procedure performed through the above explicit directives or implicit procedures is as follows.

[0202] The RRCReconfiguration message that is the target of full configuration must have a reconfigurationWithSync field in the secondaryCellGroup field during this procedure, and if this RRCReconfiguration message is a complete configuration created by combining the reference configuration and delta configuration of SCPAC, the SCPAC-related full configuration operation can be performed.

[0203] First, you can clear all dedicated radio configurations on your device. However, you may want to keep the following:

[0204] - During full configuration operation, the terminal may not clear the contents of the conditional Reconfiguration terminal variable;

[0205] - MCG C-RNTI (cell radio network temporary identifier);

[0206] - AS (access stratum) security config associated with the master key;

[0207] - SRB1 / SRB2 configuration and DRB configuration as configured by radio bearer Config or radioBearconfig2 (SRB1 (signaling radio bearer 1) / SRB2 config and DRB (data radio bearer) config as configured by radio bearerConfig or radioBearconfig2); and / or

[0208] - Logged measurement config.

[0209] And if the above RRCReconfig is for SCPAC (the reconfigurationWithSync field must exist in the secondaryCellGroup field, and this RRCReconfiguration message is a complete configuration made by combining the reference configuration and delta configuration of SCPAC),

[0210] The terminal can release or clear all current common radio configurations.

[0211] And, when applying the RLF (radio link failure) timer value, as the RLF factor of MCG, the values ​​of T310, T311, constant N310, N311 can use the values ​​existing in ue-TimersAndConstants of SIB1, and at this time, as the RLF factor of SCG, the values ​​of T310, T311, constant N310, N311 can use the default values. Since this is the PSCell migration process of SCG, it may be unclear whether the SIB1 of the corresponding target PSCell has been read during the full configuration. Accordingly, the default value can be applied.

[0212] In addition, the terminal can perform the following actions:

[0213] * Apply the default L1 parameter values ​​as specified in the corresponding physical layer specifications except for the following:

[0214] - parameters for which values ​​are provided in SIB1;

[0215] * apply the default MAC Cell Group configuration as specified in 9.2.2 of TS 38.331;

[0216] * For each srb-Identity value included in the srb-ToAddModList (SRB reconfiguration)):

[0217] Establish an RLC entity for the corresponding SRB;

[0218] * apply the default SRB configuration defined in 9.2.1 of TS 38.331 for the corresponding SRB;

[0219] As another example, the procedure for clearing / releasing the configuration information of the serving cell during SCPAC execution is described.

[0220] In one embodiment, when a terminal performs SCPAC, full configuration-related operations can be performed during the SCPAC process without invoking a separate full configuration procedure. The terminal can sequentially perform the following operations.

[0221] When a UE executes SCPAC for a target PSCell that satisfies the associated conditions, the UE (before applying the complete configuration for SCPAC):

[0222] * Release / clear all current dedicated radio configurations except for the following:

[0223] - MCG C-RNTI,

[0224] - AS seucirty config associated with the master key,

[0225] - SRB1 / SRB2 configurations and DRB configurations as configured by radioBeareConfig or radioBearerConfig2,

[0226] - The logged measurement config, and / or

[0227] - The UE variables VarConditionalReconfig;

[0228] * Release / clear all current common radio configurations;

[0229] * For SCG, use the default values ​​specified in 9.2.3 for timers T310, T311 and constants N310, N311 (for SCG, use the default values ​​specified in 9.2.3 for timers T310, T311 and constants N310, N311), and for MCG, use values ​​for timers T310, T311 and constants N310, N311 as included in ue-TimersAndConstants in SIB1 (for MCG, use values ​​for T310, T311 and constants N310, N311 as included in ue-TimersAndConstants in SIB1);

[0230] * Apply the default L1 parameter values ​​as specified in the corresponding physical layer specifications except for the following:

[0231] - parameters for which values ​​are provided in SIB1;

[0232] * apply the default MAC Cell Group configuration as specified in 9.2.2 of TS 38.331;

[0233] * For each srb-Identity value included in the srb-ToAddModList (SRB reconfiguration)):

[0234] Establish an RLC entity for the corresponding SRB;

[0235] * Apply the default SRB configuration defined in 9.2.1 for the corresponding SRB.

[0236] Meanwhile, unlike the above-described embodiment, a case where the reference configuration is empty can also be considered.

[0237] If the reference configuration is empty, the delta application method based on the settings of the source cell can be followed instead of the full configuration.

[0238] Accordingly, when performing SCPAC preparation in an inter-node call flow, when the corresponding node (S-SN) initiates, the target PSCell configuration created by the candidate SN can be written by distinguishing whether it is a delta configuration for the source cell setting or a delta configuration for the reference configuration, depending on the presence or absence of the reference configuration.

[0239] If the reference configuration does not exist in the conditional Reconfiguration transmitted to the terminal, or if there is an indicator indicating that the reference configuration does not exist in any SCPAC candidate target cell configuration or in a configuration associated therewith, when the terminal performs SCPAC, the target cell configuration may be applied as a delta configuration based on the current source cell configuration. In this case, RRCReconfiguration may be performed without applying the full configuration procedure mentioned above.

[0240] Additionally, only the SN reference configuration may be omitted. Alternatively, only the MCG part reference configuration may be omitted. Alternatively, both the SN reference configuration and the MCG part reference configuration may be omitted. If an indication that the MCG part reference configuration does not exist is transmitted in the conditional reconfiguration, the terminal may apply the MCG part configuration in a delta configuration manner based on the source configuration, and apply the remaining SCG configuration portion by applying the configuration of each target PSCell to the given SCG part reference configuration.

[0241] FIG. 11 illustrates a call flow when a reference configuration according to an embodiment of the present disclosure is not used.

[0242] Referring to FIG. 11, in step 1110, the S-SN (e.g., SN1) may transmit an SN change required message to the MN. The SN change required message may include an indicator indicating that SCPAC is started, a current source SCG cell configuration (e.g., sourceConfigSCG), a list of candidate SNs for SCPAC, a list of candidate PSCells suggested to be prepared by each candidate SN, and / or an execution condition associated with each suggested PSCell for moving to each proposed candidate target PSCell based on the source PSCell. In addition, the S-SN may not include an SN reference configuration (e.g., refconfigSCG) in the SN change required message, or may include an indicator indicating that refConfigSCG does not exist.

[0243] In step 1120, the MN can send an SN addition request message (e.g., SNAddReq) to each of the candidate SNs (e.g., SN2, SN3). The MN can convey information about candidate PSCells received from the S-SN to each of the candidate SNs (e.g., SN2, SN3) through the SN addition request message. At the same time, information about candidate PSCells recommended by the S-SN among candidate PSCells of other candidate SNs can also be conveyed through the SN addition request message. In addition, the MN can also convey the source SCG cell configuration including the SN addition request message. At this time, the MN can send the no refConfigSCG indicator received from the S-SN through the SN addition request message. Alternatively, the MN can confirm that there is no refConfigSCG in the SN change required message and convey the SNAddReq message without including refConfigSCG or including an indicator indicating that there is no refConfigSCG.

[0244] In step 1130, each candidate SN performs admission control among the recommended candidate PSCells corresponding to itself received from the MN, determines a prepared PSCell (or admitted PSCell candidate), and can create / determine a target configuration to be used in the corresponding cell (i.e., prepared PSCell). Each candidate SN can transmit an SN addition request acknowledge message (e.g., SNAddReqACK) containing information about the prepared PSCell and the target configuration to be used in the corresponding cell to the MN.

[0245] Additionally, each candidate SN may include condition information to be used for moving from one of the prepared PSCells to another candidate SN's recommended candidate PSCell and / or another cell among its own prepared PSCell in the SN addition request acknowledge message (e.g., SNAddReqACK message) and transmit it to the MN. Among these, each candidate SN may also write a condition for moving from the corresponding cell to the candidate PSCell of another candidate SN. At this time, each candidate SN may accept or reject the movement from its own prepared PSCell to the candidate PSCell of a specific candidate SN. If it accepts, the condition information for moving from its own prepared PSCell to the candidate PSCell of the specific candidate SN is added to the SN addition request acknowledge message. If it rejects, the condition information may not be included in the SN addition request acknowledge message.

[0246] Here, the target configuration (targetConfigSCG) to be used in the corresponding cell (i.e., prepared PSCell) is a delta configuration for creating a configuration to be used in the determined candidate PSCell based on the source SCG configuration in the S-SN received from the MN. The configuration of each candidate SN transmitted from A corresponding to step 30 (e.g., SN RRCReconfig) may have the structure of Fig. 12a.

[0247] In step 1140, the MN receives the above information from each candidate SN, and based on the above information, determines whether any of the recommended PSCells has failed preparation in the SN. If not all of the recommended PSCells have been prepared in each candidate SN (e.g., if there is no information about prepared PSCells in the message received in step 1130), the information about the PSCells that have failed preparation can be retransmitted to each candidate SN and S-SN. At this time, the SN modification request (e.g., SNModReq) message can be used.

[0248] Upon receiving the SN modification request message, each candidate SN and S-SN updates the condition information considering only the prepared (i.e., admitted) PSCells from the candidate PSCells recommended to it (i.e., if conditions for all candidate PSCells were previously created, some of them are removed), and updates the measurement configuration including the condition information (i.e., for the combination of MO and reportconfig for the conditions of all candidate PSCells previously, some are removed except for those for prepared candidate cells), so that the target cell configuration including the conditions and measurement configuration for only the admitted (prepared) PSCells can be delivered to the MN through the SN modification request acknowledge (e.g., SNModReqACK) message.

[0249] At step 1150, the MN may receive an SN modification request acknowledge (e.g., SNModReqACK) message.

[0250] Basically, in the reference configuration operation, the source cell configuration of the current terminal can be seen as replacing the reference configuration.

[0251] At step 1160, since the MN knows that the S-SN initially starts with no reference configuration, it can know that the candidate SN and the targetConfigSCGs received from the S-SN are settings unrelated to the reference configuration. Through this, the MN can configure the SN RRCReconfiguration by combining the sourceConfigSCG and targetConfigSCG currently set in the terminal. Based on this configuration information, the MCG configuration (MCG parts 1, 2, 3, and 4 in Fig. 12b) can be configured. The RRCReconfiguration in the MN format, which is a combination of the MCG configuration and the SCG configuration (SN RRCReconfiguration), can be called a complete configuration (B-1). In addition, the MN can create multiple MCG configurations corresponding to the SCG configuration for multiple PSCells, and based on this, create an MCG reference configuration (or named refConfigMCG) having common arguments among the multiple MCG configurations (this will be referred to as case 1. Case 1 represents the case of creating an MCG reference configuration). Or, since there is no reference configuration in the SCG part, the MN can create an RRCReconfiguration that combines the MCG configuration excluding the sourceConfigMCG (i.e., the MCG configuration information of the current terminal) and the targetConfigSCG without the MCG reference configuration (this will be referred to as case 2).Case 2 represents a case where an MCG reference configuration is not created). This information is transmitted to the terminal as the "target PSCell configuration."

[0252] Finally, the MN can assign / map condition information and target cell configuration information for target PSCells to the condReconfig Id and transmit them to the UE. At this time, SCPAC settings can be added (additionally mapped) to each condReconfig Id.

[0253] As for each target PSCell configuration information, in case 2, the MN can transmit the target PSCell configuration to the terminal without a separate reference configuration. In case 1, the MN can transmit refConfigMCG to the terminal as the reference configuration, and the remaining part, i.e., the combination of MCG delta and target ConfigSCG, can be transmitted to the terminal as the target PSCell configuration.

[0254] Information transmitted from the MN to the terminal may be transmitted to the terminal via an RRC reset message in step 1170. In step 1180, the terminal may transmit an RRC reset complete message to the MN.

[0255] In step 1190, the terminal that received the above information can perform condition evaluation. If the condition for SCPAC (e.g., one of the conditions of SCPAC config) is satisfied, in case 2, the terminal can apply the target PSCell configuration of the corresponding target cell over the current configuration of the terminal (applying delta configuration based on the source configuration). In case 1, in case of SCG, the terminal applies the sCG part of the target PSCell configuration over the current source scg configuration, and in case of the remaining part, i.e., MCG part, clears / releases the parameters corresponding to the MCG part, performs a full configuration operation only for the MCG part, and configures the MCG configuration by combining the remaining part of the target PSCell configuration excluding the SCG part and the MCG reference configuration. The terminal can apply the MCG and SCG configurations configured in this way by combining them. If the condition for SCPAC is satisfied, the terminal can execute SCPAC for the target PSCell, in which case the above configuration can be applied.

[0256] The terminal may transmit an RRC reconfiguration completion message to the MN. The RRC reconfiguration completion message may include triggered PSCell information.

[0257] FIG. 12a illustrates the structure of a setting configured by each candidate SN when an SN reference configuration according to one embodiment of the present disclosure is not used.

[0258] Referring to Fig. 12a, SN RRCReconfig can include SourceConfigSCG and TargetConfigSCG. SN can create TargetConfigSCG (= delta component corresponding to sourceConfigSCG).

[0259] FIG. 12b illustrates the structure of the MCG part setting and the MCG reference configuration for each SN RRCReconfig when the SN reference configuration according to one embodiment of the present disclosure is not used.

[0260] Referring to Fig. 12b, the MN can create an MCG part configuration for each SN RRCReconfig (i.e., a part of the RRCReconfiguration in the MN format, called MCG configuration). In Case 1, the MN can create an MCG reference configuration (i.e., refconfigMCG) based on the MCG part configurations. In Case 2, the MN may not create an MCG reference configuration.

[0261] FIG. 12c illustrates the structure of a target cell setting of SCPAC when an SN reference configuration according to an embodiment of the present disclosure is not used.

[0262] Referring to Fig. 12c, the MN can compile the remaining MCG / SCG deltas excluding the MCG ref and SCG ref to create a final candidate PSCell config (condRRCReconfig for SCPAC) and configure it for the terminal. At this time, the MN can also transmit the SCPAC reference configuration to the terminal.

[0263] According to the embodiments of the present disclosure described above, it is possible to know which node creates the reference configuration and delta configuration for SCPAC. Furthermore, according to the embodiments of the present disclosure, a complete configuration can be formed by combining the reference configuration and the delta configuration, and the terminal can apply the final complete configuration.

[0264] Meanwhile, the order of description in the drawings explaining the method of the present disclosure does not necessarily correspond to the order of execution, and the order of precedence may be changed or executed in parallel.

[0265] Alternatively, the drawings illustrating the method of the present disclosure may omit some components and include only some components without detracting from the essence of the present disclosure.

[0266] In addition, the method of the present disclosure may be implemented by combining some or all of the contents included in each embodiment within a scope that does not harm the essence of the disclosure.

[0267] Meanwhile, the embodiments of the present disclosure disclosed in this specification and drawings are merely specific examples presented to easily explain the technical content of the present disclosure and aid in understanding of the present disclosure, and are not intended to limit the scope of the present disclosure. In other words, it will be apparent to those skilled in the art to which the present disclosure pertains that other modified examples based on the technical concept of the present disclosure are possible. Furthermore, the above-described embodiments may be combined and operated as needed.

Claims

1. A method performed by a MN (master node) in a wireless communication system, A step of receiving an SN change request message for a subsequent CPAC (conditional PSCell (primary SCG (secondary cell group) cell) addition or change) from a source SN (secondary node), wherein the SN change request message includes an SCG (secondary cell group) reference configuration; A step of transmitting an SN addition request message including the SCG criteria setting to a candidate SN; A step of receiving an SN addition request acknowledgment message including settings for a candidate PSCell from the above candidate SN; and For the above subsequent CPAC, a step of transmitting a reference setting and a setting for the candidate PSCell to the terminal is included, A method wherein the above criteria setting includes the SCG criteria setting and the MCG (master cell group) criteria setting generated by the MN.

2. In paragraph 1, The above criteria settings and the settings for the candidate PSCell are included in an RRC (radio resource control) reset message and transmitted to the terminal, and A method characterized in that the RRC reset message further includes condition information related to the subsequent CPAC.

3. In paragraph 1, A method characterized in that the settings for the above candidate PSCell are provided as delta settings on top of the above SCG reference settings.

4. In paragraph 1, A method characterized by further comprising the step of transmitting a trigger for subsequent CPAC setup to the source SN.

5. In a method performed by a terminal in a wireless communication system, For subsequent CPAC (conditional PSCell (primary SCG (secondary cell group) cell) addition or change), a step of receiving a reference configuration and a configuration for a candidate PSCell from a MN (master node); and A step of determining whether to execute the subsequent CPAC based on the above criteria setting and the setting for the candidate PSCell, The above criteria setting includes the SCG (secondary cell group) criteria setting transmitted from the source SN (secondary node) to the MN and the MCG (master cell group) criteria setting generated by the MN, and A method wherein the settings for the above candidate PSCell are transmitted from the candidate SN to the MN.

6. In paragraph 5, The above criteria setting and the setting for the candidate PSCell are included in an RRC (radio resource control) reset message and received from the MN, and A method characterized in that the RRC reset message further includes condition information related to the subsequent CPAC.

7. In paragraph 6, The step of determining whether to execute the above subsequent CPAC includes the step of evaluating whether a condition corresponding to the candidate PSCell is satisfied based on the above condition information, and A method, characterized in that if a condition corresponding to the candidate PSCell is satisfied, the method further comprises a step of executing a subsequent CPAC for the candidate PSCell.

8. In paragraph 7, The steps to conduct a follow-up CPAC for the above candidate PSCell are: Step to skip releasing terminal variables; For SCG, a step of applying predefined default values ​​to timers and constants associated with RLF (radio link failure); and A method, characterized by comprising a step of applying basic MAC (medium access control) cell group settings.

9. In paragraph 5, A method characterized in that the settings for the above candidate PSCell are provided as delta settings on top of the above SCG reference settings.

10. In a wireless communication system, in the MN (master node), Transmitter and receiver; and A control unit comprising: Receive an SN change request message for a subsequent CPAC (conditional PSCell (primary SCG (secondary cell group) cell) addition or change) from a source SN (secondary node), wherein the SN change request message includes an SCG (secondary cell group) reference configuration, To the candidate SN, a SN addition request message including the above SCG criteria setting is transmitted, Receive an SN addition request acknowledgment message including the configuration for the candidate PSCell from the above candidate SN, and For the above subsequent CPAC, it is set to transmit the reference setting and the setting for the candidate PSCell to the terminal, The above criteria setting includes the SCG criteria setting and the MCG (master cell group) criteria setting generated by the MN.

11. In paragraph 10, The above criteria settings and the settings for the candidate PSCell are included in an RRC (radio resource control) reset message and transmitted to the terminal, and MN, characterized in that the RRC reset message further includes condition information related to the subsequent CPAC.

12. In paragraph 10, An MN characterized in that the settings for the above candidate PSCell are provided as delta settings on top of the above SCG reference settings.

13. In a wireless communication system, at a terminal, Transmitter and receiver; and A control unit comprising: For subsequent CPAC (conditional PSCell (primary SCG (secondary cell group) cell) addition or change), receive reference configuration and configuration for candidate PSCell from MN (master node), and It is set to determine whether to execute the subsequent CPAC based on the above criteria setting and the setting for the candidate PSCell, The above criteria setting includes the SCG (secondary cell group) criteria setting transmitted from the source SN (secondary node) to the MN and the MCG (master cell group) criteria setting generated by the MN, and The settings for the above candidate PSCell are transmitted from the candidate SN to the MN.

14. In paragraph 13, The above criteria setting and the setting for the candidate PSCell are included in an RRC (radio resource control) reset message and received from the MN, and A terminal, characterized in that the RRC reset message further includes condition information related to the subsequent CPAC.

15. In paragraph 14, The control unit is set to evaluate whether a condition corresponding to a candidate PSCell is satisfied based on the condition information to determine whether to execute the subsequent CPAC, and If the condition corresponding to the above candidate PSCell is satisfied, the control unit: Skip releasing terminal variables, For SCG, predefined default values ​​are applied to timers and constants associated with RLF (radio link failure), and A terminal further characterized by being configured to apply basic MAC (medium access control) cell group settings.

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