Method and apparatus for continuous performing condition pscell addition and change in wireless communication system

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting a high data transmission rate. Embodiments of the present disclosure may provide a method and apparatus for continuously performing conditional PSCell addition and change in a next generation mobile communication system.

Description

Technical Field

[0001] The present disclosure relates to operations of a terminal and a base station in a mobile communication system. Background Art

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

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

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

[0005] In addition, in terms of air interface architecture / protocol, standardization is already underway on technologies such as the Industrial Internet of Things (IIoT) for supporting new services through interworking and integration with other industries, Integrated Access and Backhaul (IAB) for providing nodes for network service area expansion by supporting wireless backhaul links and access links in an integrated manner, mobility enhancement including conditional switching and dual active protocol stack (DAPS) switching, and two-step random access (NR's 2-step random access channel (RACH)) for simplifying the random access process. In terms of system architecture / services, standardization is also underway on the 5G baseline architecture (e.g., service-based architecture or service-based interface) for combining network function virtualization (NFV) and software defined networking (SDN) technologies, and mobile edge computing (MEC) for receiving services based on UE location.

[0006] As 5G mobile communication systems are commercialized, the number of connected devices, which has been growing exponentially, will be connected to the communication network, and it is accordingly expected that enhanced functions and performance of the 5G mobile communication systems and integrated operations of the connected devices will be necessary. To this end, new research is planned related to: extended reality (XR) for effectively supporting augmented reality (AR), virtual reality (VR), mixed reality (MR), etc., improving 5G performance and reducing complexity by utilizing artificial intelligence (AI) and machine learning (ML), AI service support, metaverse service support, and drone communication.

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

[0008] The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with respect to the present disclosure. Summary of the invention

[0009] Technical issues

[0010] The present disclosure is an improved technology for conditional primary and secondary cell group (SCG) cell (PSCell) addition and change (CPA) and conditional PSCell change (CPC); conditional PSCell addition and change (CPAC) is applied to the existing NR system. In the case of the existing NR system, after the secondary cell group (SCG) change is performed, all candidate SCG configurations stored in the UE are released, making continuous CPAC operation impossible. That is, once CPAC is applied and executed to the UE, in order to perform CPAC operation again, the base station must again pass the CPAC configuration down to the UE through the radio resource control (RRC) configuration.

[0011] Aspects of the present disclosure are intended to at least solve the above problems and / or disadvantages and to provide at least the advantages described below. Therefore, one aspect of the present disclosure is to provide a continuous CPAC support method.

[0012] Additional aspects will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the presented embodiments.

[0013] Solution to the problem

[0014] According to one aspect of the present disclosure, a method performed by a terminal in a wireless communication system is provided. The method includes: receiving a first message including conditional reconfiguration information from a base station, the conditional reconfiguration information including configuration information of at least one candidate primary and secondary cell group (SCG) cell (PSCell), information about at least one execution condition of conditional PSCell addition (CPA) or conditional PSCell change (CPC) of at least one candidate PSCell, and information indicating that the conditional reconfiguration information is maintained after the PSCell addition or PSCell change; identifying the first PSCell when at least one execution condition for the first PSCell among the at least one candidate PSCell is satisfied for CPA or CPC based on the conditional reconfiguration information; sending a second message for adding the first PSCell or for changing to the first PSCell to the base station; and evaluating at least one execution condition of at least one candidate PSCell.

[0015] In an embodiment, the method further includes: identifying a second PSCell when, based on the conditional reconfiguration information, at least one execution condition for a second PSCell among at least one candidate PSCell for CPC is satisfied; and sending a third message to the base station for changing from the first PSCell to the second PSCell.

[0016] In an embodiment, the method further includes: sending capability information of the terminal to the base station, the capability information of the terminal including information indicating that the terminal supports maintaining conditional reconfiguration information after a PSCell addition procedure or a PSCell change procedure is performed.

[0017] In an embodiment, the first message is a message for modifying a Radio Resource Control (RRC) connection.

[0018] In an embodiment, information indicating that the conditional reconfiguration information is maintained after a PSCell addition or a PSCell change is configured to each of at least one candidate PSCell.

[0019] According to another aspect of the present disclosure, a method performed by a first base station in a wireless communication system is provided. The method includes: sending a first message including conditional reconfiguration information to a terminal, the conditional reconfiguration information including configuration information of at least one candidate primary and secondary cell group (SCG) cell (PSCell), information about at least one execution condition of conditional PSCell addition (CPA) or conditional PSCell change (CPC) of at least one candidate PSCell, and information indicating that the conditional reconfiguration information is maintained after the PSCell addition or PSCell change; based on the conditional reconfiguration information, for CPA or CPC, at least one execution condition for a first PSCell among at least one candidate PSCell is satisfied, receiving a second message for adding a first PSCell or for changing to a first PSCell from the terminal; and sending a third message for adding a first PSCell or for changing to a first PSCell to a second base station of the first PSCell, wherein the conditional reconfiguration information is maintained after adding the first PSCell or changing to the first PSCell.

[0020] In an embodiment, the method further includes: receiving, from the terminal, a fourth message for changing from the first PSCell to the second PSCell when at least one execution condition for a second PSCell among at least one candidate PSCell is satisfied for CPC based on the conditional reconfiguration information.

[0021] In an embodiment, the method further includes: receiving capability information of the terminal from the terminal, the capability information of the terminal including information indicating that the terminal supports maintaining the conditional reconfiguration information after the PSCell addition procedure or the PSCell change procedure is performed.

[0022] In an embodiment, the first message is a message for modifying a Radio Resource Control (RRC) connection.

[0023] In an embodiment, information indicating that the conditional reconfiguration information is maintained after a PSCell addition or a PSCell change is configured to each of at least one candidate PSCell.

[0024] According to another aspect of the present disclosure, a terminal in a wireless communication system is provided. The terminal includes: a transceiver; and a controller coupled to the transceiver and configured to: receive a first message including conditional reconfiguration information from a base station, the conditional reconfiguration information including configuration information of at least one candidate primary and secondary cell group (SCG) cell (PSCell), information about at least one execution condition of conditional PSCell addition (CPA) or conditional PSCell change (CPC) of at least one candidate PSCell, and information indicating that the conditional reconfiguration information is maintained after the PSCell addition or PSCell change, and based on the conditional reconfiguration information, for CPA or CPC, at least one execution condition for a first PSCell among at least one candidate PSCell is satisfied, identify the first PSCell, send a second message for adding the first PSCell or for changing to the first PSCell to the base station, and evaluate at least one execution condition of at least one candidate PSCell.

[0025] According to another aspect of the present disclosure, a first base station in a wireless communication system is provided. The first base station includes: a transceiver; and a controller, which is coupled to the transceiver and configured to: send a first message including conditional reconfiguration information to a terminal, the conditional reconfiguration information including configuration information of at least one candidate primary and secondary cell group (SCG) cell (PSCell), information about at least one execution condition of conditional PSCell addition (CPA) or conditional PSCell change (CPC) of at least one candidate PSCell, and information indicating that the conditional reconfiguration information is maintained after the PSCell addition or PSCell change, and when at least one execution condition for a first PSCell among at least one candidate PSCell is satisfied for CPA or CPC based on the conditional reconfiguration information, receive a second message for adding the first PSCell or for changing to the first PSCell from the terminal, and send a third message for adding the first PSCell or for changing to the first PSCell to a second base station of the first PSCell, wherein the conditional reconfiguration information is maintained after the addition of the first PSCell or the change to the first PSCell.

[0026] Advantageous Effects of the Invention

[0027] According to the continuous CPAC support method proposed in the present disclosure, the base station can configure and indicate a candidate SCG for continuous CPAC for the UE, so that the UE can maintain the corresponding configuration even after the SCG configuration is changed, and the base station can support continuous CPAC operation according to channel conditions, etc. without additional RRC configuration. Therefore, unnecessary RRC signaling can be reduced, and dynamic CPAC operation customized for the channel state can be performed.

[0028] Other aspects, advantages, and salient features of the present disclosure will become apparent to those skilled in the art from the following detailed description which, in conjunction with the accompanying drawings, discloses various embodiments of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The above and other aspects, features and advantages of certain embodiments of the present disclosure will become more apparent through the following description in conjunction with the accompanying drawings, in which:

[0030] Figure 1A is a diagram showing a structure of a Long Term Evolution (LTE) system according to an embodiment of the present disclosure;

[0031] Figure 1B is a diagram showing a radio protocol structure in an LTE system according to an embodiment of the present disclosure;

[0032] Figure 1C is a diagram showing a structure of a next generation mobile communication system according to an embodiment of the present disclosure;

[0033] Figure 1D is a diagram showing a radio protocol structure of a next generation mobile communication system according to an embodiment of the present disclosure;

[0034] Figure 1E is a diagram illustrating an overall operation of performing a conditional PSCell addition procedure in an LTE system or an NR system according to an embodiment of the present disclosure;

[0035] Figure 1F is a diagram illustrating an overall operation of performing a conditional PSCell change procedure in an LTE system or an NR system according to an embodiment of the present disclosure;

[0036] Figure 1G is a diagram showing the overall operation of continuously performing a conditional PSCell adding process according to the first embodiment of the present disclosure;

[0037] Figure 1H is a diagram showing an overall operation of continuously performing a conditional PSCell change process according to a second embodiment of the present disclosure;

[0038] Fig. 1Iis a diagram showing the structure of a Medium Access Control (MAC) Control Element (CE) signaling for continuously updating a candidate SCG configuration to support conditional PSCell addition and change according to an embodiment of the present disclosure;

[0039] Figure 1J is a diagram illustrating a UE operation to which an embodiment of the present disclosure is applied according to an embodiment of the present disclosure, which embodies the UE operation when conditional PSCell addition and change are continuously applied;

[0040] Figure 1K is a diagram illustrating a base station operation to which an embodiment of the present disclosure is applied according to an embodiment of the present disclosure, which embodies the base station operation when conditional PSCell addition and change are continuously applied;

[0041] Figure 1L is a block diagram showing an internal structure of a UE according to an embodiment of the present disclosure; and

[0042] Figure 1M is a block diagram showing the configuration of a base station according to an embodiment of the present disclosure.

[0043] Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures. DETAILED DESCRIPTION

[0044] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of the various embodiments of the present disclosure as defined by the claims and their equivalents. It includes various specific details to assist in understanding, but these details are considered to be exemplary only. Therefore, it will be appreciated by those of ordinary skill in the art that various changes and modifications may be made to the various embodiments described herein without departing from the scope and spirit of the present disclosure. In addition, for the sake of clarity and conciseness, descriptions of well-known functions and structures may be omitted.

[0045] The terms and words used in the following description and claims are not limited to the bibliographical meanings, but are merely used by the inventor to enable a clear and consistent understanding of the present disclosure. Therefore, it will be apparent to those skilled in the art that the following description of various embodiments of the present disclosure is provided for illustrative purposes only and not for the purpose of limiting the present disclosure as defined by the appended claims and their equivalents.

[0046] It should be understood that the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a component surface" includes reference to one or more of such surfaces.

[0047] For the same reason, in the accompanying drawings, some components may be exaggerated, omitted or schematically shown. In addition, the size of each component does not fully reflect the actual size. In the accompanying drawings, the same or corresponding components are provided with the same reference numerals.

[0048] By referring to the embodiments described in detail below in conjunction with the accompanying drawings, the advantages and features of the present disclosure and the ways to achieve them will be apparent. However, the present disclosure is not limited to the embodiments set forth below, but can be implemented in various different forms. The following embodiments are provided only to fully disclose the present disclosure and inform those skilled in the art of the scope of the present disclosure, and the present disclosure is limited only by the scope of the attached claims. Throughout the specification, the same or similar reference numerals represent the same or similar components.

[0049] Here, it will be understood that each box of the flowchart diagram and the combination of boxes in the flowchart diagram can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device create equipment for realizing the function specified in the flowchart box. These computer program instructions can also be stored in a computer-available or computer-readable memory, which can instruct the computer or other programmable data processing device to act in a particular way, so that the instructions stored in the computer-available or computer-readable memory produce products including instruction equipment for realizing the function specified in the flowchart box. Computer program instructions can also be loaded on a computer or other programmable data processing device, so that a series of operating steps are performed on a computer or other programmable device to produce a computer-implemented process, so that the instructions executed on a computer or other programmable device provide steps for realizing the function specified in the flowchart box.

[0050] In addition, each box of the flow chart can represent a module, a fragment or a portion of the code, which includes one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative embodiments, the functions marked in the box may not occur in order. For example, two boxes shown in succession can actually be executed substantially simultaneously, or these boxes can sometimes be executed in reverse order, depending on the functions involved.

[0051] Here, "unit" refers to a software element or hardware component that performs a predetermined function, such as a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC). However, "unit" does not always have a meaning limited to software or hardware. "Unit" can be constructed to be stored in an addressable storage medium or to execute one or more processors. Therefore, "unit" includes, for example, software components, object-oriented software components, class components or task components, processes, functions, attributes, procedures, subroutines, program code segments, drivers, firmware, microcodes, circuits, data, databases, data structures, tables, arrays and parameters. The components and functions provided by "units" can be combined into fewer components and "units", or divided into more components and "units". In addition, components and "units" or "modules" can be implemented as one or more central processing units (CPUs) in a reproduction device or a secure multimedia card.

[0052] Specific terms used in the following description are provided to facilitate understanding of the present disclosure, and the use of these specific terms may be modified differently without departing from the technical concept of the present disclosure.

[0053] In the following description, for the convenience of description, terms for identifying access nodes, terms referred to as network entities, terms indicating messages, terms representing interfaces between network objects, terms for various types of identification information, etc. are used. Therefore, the present disclosure is not limited to the terms described below, and other terms indicating components having technical meanings equivalent to the terms described in the present disclosure may be used.

[0054] For ease of description, the present disclosure uses terms and names defined in the specifications of the 3rd Generation Partnership Project Long Term Evolution (3GPP LTE). However, it should be understood that the present disclosure is not limited to the terms and names and can also be applied to systems complying with other standards.

[0055] Figure 1A is a diagram showing a structure of an LTE system according to an embodiment of the present disclosure.

[0056] refer to Figure 1A As shown in the figure, the radio access network of the LTE system includes next-generation base stations (evolved Node B, hereinafter referred to as eNB, Node B or base station) 1a-05, 1a-10, 1a-15 and 1a-20, mobility management entity (MME) 1a-25 and serving gateway (S-GW) 1a-30. User equipment (hereinafter, UE or terminal) 1a-35 is connected to the external network through eNB 1a-05 to 1a-20 and S-GW 1a-30.

[0057] refer to Figure 1A, eNB 1a-05 to 1a-20 correspond to the existing Node B of the UMTS system. eNB 1a-05 to 1a-20 are connected to UE 1a-35 through a radio channel and perform a more complex role than the existing Node B. In the LTE system, in addition to real-time services such as Voice over Internet Protocol (VoIP) through the Internet Protocol, all user services are served through a shared channel, so a device for collecting and scheduling status information (such as buffer status, available transmission power status, and channel status) of UE 1a-35 is required. Here, eNB 1a-05 to 1a-20 is responsible for collection and scheduling. One eNB 1a-05 to 1a-20 generally controls multiple cells. For example, in order to achieve a transmission rate of 100Mbps, the LTE system uses orthogonal frequency division multiplexing (hereinafter, OFDM) as a radio access technology in a bandwidth of, for example, 20MHz. In addition, adaptive modulation and coding (hereinafter, AMC) that determines the modulation scheme and channel coding rate according to the channel state of UE 1a-35 is applied. S-GW 1a-30 is a device for providing data bearers, and generates or removes data bearers according to the control of MME 1a-25. MME 1a-25 is a device for performing a mobility management function and various control functions of UE 1a-35, and is connected to a plurality of base stations 1a-05 to 1a-20.

[0058] Figure 1B is a diagram illustrating a radio protocol structure in an LTE system according to an embodiment of the present disclosure.

[0059] refer to Figure 1B , the radio protocols of the LTE system include Packet Data Convergence Protocol (PDCP) b-05 and 1b-40, Radio Link Control (RLC) b-10 and 1b-35, and Medium Access Control (MAC) 1b-15 and 1b-30 in the UE and eNB respectively. PDCP 1b-05 and 1b-40 are responsible for operations such as IP header compression / recovery. The main functions of PDCP 1b-05 or 1b-40 are summarized as follows.

[0060] -Header compression and decompression functions: Robust Header Compression (ROHC) only

[0061] -User data transmission function

[0062] - In-sequence delivery function (in-sequence delivery of upper layer packet data units (PDUs) during PDCP re-establishment in RLC Acknowledged Mode (AM))

[0063] - Reordering functionality (for split bearers in Dual Connectivity (DC) (supporting RLC AM only): PDCP PDU routing for transmission and PDCP PDU reordering for reception)

[0064] - Duplicate detection function (duplicate detection of lower layer service data units (SDUs) during PDCP reestablishment of RLC AM)

[0065] - Retransmission functionality (for RLC AM, retransmission of PDCP SDUs at handover, and for split bearers in DC, retransmission of PDCP PDUs during PDCP data recovery)

[0066] -Encryption and decryption functions

[0067] -Timer-based SDU discard function (timer-based SDU discard in uplink)

[0068] Radio link control (hereinafter referred to as RLC) 1b-10 or 1b-35 reconstructs a PDCP packet data unit (PDU) in an appropriate size to perform an automatic repeat request (ARQ) operation, etc. The main functions of the RLC are summarized as follows.

[0069] -Data transmission function (transmission of upper layer PDU)

[0070] -ARQ function (error correction through ARQ (only for AM data transmission))

[0071] - Concatenation, segmentation and reassembly function (concatenation, segmentation and reassembly of RLC SDU (only for unacknowledged mode (UM) and AM data transmission))

[0072] - Re-segmentation function (resegmentation of RLC data PDU (only for AM data transmission))

[0073] - Reordering function (reordering of RLC data PDU (only for UM and AM data transmission)

[0074] - Duplicate detection function (Duplicate detection (only for UM and AM data transmission))

[0075] - Error detection function (protocol error detection (for AM data transmission only))

[0076] -RLC SDU discard function (RLC SDU discard (only for UM and AM data transmission))

[0077] -RLC reconstruction function

[0078] MAC 1b-15 and 1b-30 are connected to several RLC layer devices constituted in one terminal, and perform operations of multiplexing RLC PDUs in MAC PDUs and demultiplexing RLC PDUs from MAC PDUs. The main functions of MAC are summarized as follows.

[0079] - Mapping function (mapping between logical channels and transport channels)

[0080] - Multiplexing and demultiplexing functions (multiplexing MAC SDUs belonging to one or different logical channels to / demultiplexing MAC SDUs belonging to one or different logical channels delivered to / from a transport block (TB) delivered to / from the physical layer on the transport channel)

[0081] -Scheduling information reporting function

[0082] -Hybrid Automatic Repeat Request (HARQ) functionality (error correction through HARQ)

[0083] - Priority handling function between logical channels (priority handling between logical channels of a UE)

[0084] - Priority handling function between UEs (priority handling between UEs with the help of dynamic scheduling)

[0085] -MBMS service identification function

[0086] -Transmission format selection function

[0087] - Fill function

[0088] The physical layer (PHY) 1b-20 and 1b-25 perform operations of channel coding and modulating upper layer data, making them as OFDM symbols, and sending them to the radio channel, or demodulating OFDM symbols received through the radio channel, channel decoding them, and sending them to the upper layer. In addition, the physical layer also uses hybrid ARQ (HARQ) for additional error correction, in which the receiving stage sends 1 bit as to whether the receiving stage has received the packet sent from the transmitting stage, which is called HARQ ACK / NACK. The downlink HARQ ACK / NACK in response to the uplink transmission is transmitted via the physical hybrid ARQ indicator channel (PHICH). The uplink HARQ ACK / NACK in response to the downlink transmission is transmitted via the physical uplink control channel (PUCCH) or the physical uplink shared channel (PUSCH) physical channel.

[0089] Meanwhile, PHY layers 1b-20 and 1b-25 may include one or more frequencies / carriers, and a technique for simultaneously configuring and using multiple frequencies is called carrier aggregation (CA). According to the CA technique, instead of using only one carrier for communication between a terminal (or user equipment (UE)) and a base station (E-UTRAN Node B (eNB)), one primary carrier and multiple secondary carriers are used, and thus data capacity can be greatly increased by the number of secondary carriers. Meanwhile, in LTE, a cell served by a base station using a primary carrier is called a primary cell (PCell), and a cell served by a base station using a secondary carrier is called a secondary cell (SCell).

[0090] Although not shown in the drawings, a radio resource control (hereinafter, referred to as RRC) layer exists above the PDCP layer of the UE and the base station, respectively, and the RRC layer may exchange configuration control messages related to access and measurement for radio resource control.

[0091] Figure 1C is a diagram illustrating a structure of a next generation mobile communication system according to an embodiment of the present disclosure.

[0092] refer to Figure 1C , the radio access network of the next generation mobile communication system may include a next generation base station (new radio node B (NR NB) (hereinafter referred to as NR gNB) 1c-10 and a new radio core network (NR CN) or a next generation core network (NGCN) 1c-05). The new radio user equipment (NR UE) or UE 1c-15 accesses the external network via the NR gNB 1c-10 and the NR CN 1c-05.

[0093] refer to Figure 1C, NR gNB 1c-10 corresponds to the evolved Node B (eNB) of the conventional LTE system. NR gNB 1c-10 is connected to NR UE 1c-15 through a radio channel and can provide better services than the conventional Node B. Since all user service data are served through shared channels in the next generation mobile communication system, a device for checking the buffer status information, available transmission power status information, channel status information, etc. of the UE and performing scheduling is required and NR gNB 1c-10 is used as such a device. A single NR gNB 1c-10 typically controls multiple cells. A bandwidth greater than the maximum bandwidth of LTE can be given to achieve an ultra-high data rate, and beamforming technology can be added to radio access technologies such as orthogonal frequency division multiplexing (hereinafter referred to as OFDM). In addition, adaptive modulation and coding (hereinafter referred to as AMC) is also used to determine the modulation scheme and channel coding rate according to the channel state of UE 1c-15. NR CN 1c-05 performs functions such as mobility support, bearer configuration, quality of service (QoS) configuration, etc. NR CN 1c-05 is a device for performing mobility management functions and various control functions of UE 1c-15, and is connected to multiple base stations 1c-10. In addition, the next-generation mobile communication system can cooperate with the traditional LTE system, and NR CN 1c-05 is connected to MME 1c-25 through a network interface. MME1c-25 is connected to the traditional eNB 1c-30.

[0094] Figure 1D is a diagram illustrating a radio protocol structure of a next generation mobile communication system according to an embodiment of the present disclosure.

[0095] refer to Figure 1D The radio protocol structure of the next generation mobile communication system includes NRSDAP 1d-01 and 1d-45, NR PDCP 1d-05 and 1d-40, NR RLC 1d-10 and 1d-35, NR MAC 1d-15 and 1d-30, and NR PHY 1d-20 and 1d-25 for UE and NR base station respectively.

[0096] The main functions of NR SDAP 1d-01 or 1d-45 may include some of the following functions.

[0097] - User data transmission function (transmission of user plane data)

[0098] -Mapping function between QoS flows and DRBs for both DL and UL)

[0099] -Marking function for QoS flow ID for both DL and UL (marking QoS flow ID in both DL and UL packets)

[0100] - UL SDAP PDU's Reflective QoS flow to data bearer mapping function (UL SDAP PDU's Reflective QoS flow to DRB mapping).

[0101] For SDAP layer devices, the UE can be configured through RRC messages regarding whether to use the header of the SDAP layer device or the function of the SDAP layer device for each PDCP layer device, for each bearer, or for each logical channel, and in the case of configuring the SDAP header, the NAS QoS reflection configuration 1-bit indicator (NAS reflection QoS) and the AS QoS reflection configuration 1-bit indicator (AS reflection QoS) of the SDAP header can indicate that the UE can update or reconfigure the QoS flow of the uplink and downlink and the mapping information for the data bearer. The SDAP header may include QoS flow ID information indicating QoS. QoS information can be used as data processing priority, scheduling information, etc. to support smooth services.

[0102] The main functions of NR PDCP 1d-05 or 1d-40 may include some of the following functions.

[0103] -Header compression and decompression functions: ROHC only

[0104] -User data transfer function

[0105] - In-sequence delivery function (in-sequence delivery of upper layer PDU)

[0106] - Out-of-order delivery function (out-of-order delivery of upper layer PDUs)

[0107] - Reordering function (for reordering of received PDCP PDUs)

[0108] - Duplicate detection function (duplicate detection of lower layer SDU)

[0109] -Retransmission function (retransmission of PDCP SDU)

[0110] -Encryption and decryption functions

[0111] -Timer-based SDU discard function (timer-based SDU discard in uplink)

[0112] In the above, the reordering function of the NR PDCP layer refers to a function of reordering PDCP PDUs received from a lower layer based on a PDCP sequence number (SN), and may include a function of delivering the reordered data to an upper layer in sequence, a function of delivering data immediately without considering the sequence, a function of recording lost PDCP PDUs by reordering PDCP PDUs, a function of reporting status information of lost PDCP PDUs to a transmitter, and a function of requesting retransmission of lost PDCP PDUs.

[0113] The main functions of NR RLC 1d-10 or 1d-35 may include some of the following functions.

[0114] -Data transmission function (transmission of upper layer PDU)

[0115] - In-sequence delivery function (in-sequence delivery of upper layer PDU)

[0116] - Out-of-order delivery function (out-of-order delivery of upper layer PDUs)

[0117] -ARQ function (error correction through ARQ)

[0118] - Concatenation, segmentation and reassembly function (concatenation, segmentation and reassembly of RLC SDU)

[0119] - Re-segmentation function (resegmentation of RLC data PDU)

[0120] - Reordering function (reordering of RLC data PDU)

[0121] - Duplicate detection function

[0122] -Error detection function (protocol error detection)

[0123] -RLC SDU discard function

[0124] -RLC reconstruction function

[0125] In the above, the in-sequence delivery function of the NR RLC device refers to a function of delivering the RLC SDU received from the lower layer to the upper layer in sequence, and may include: a function of reassembling multiple RLC SDUs segmented from the RLC SDU and delivering the RLC SDU when a segmented RLC SDU is received, a function of reordering the received RLC PDU based on the RLC sequence number (SN) or the PDCP SN, a function of recording the lost RLC PDU by reordering the RLC PDU, a function of reporting the status information of the lost RLC PDU to the transmitter, a function of requesting retransmission of the lost RLC PDU, a function of delivering only the RLC SDU before the lost RLC SDU in sequence to the upper layer in the presence of lost RLC SDUs, a function of delivering all RLC SDUs received before the timer is started in sequence to the upper layer when a certain timer expires despite the presence of lost RLC SDUs, or a function of delivering all RLC SDUs received until the current time in sequence to the upper layer when a certain timer expires despite the presence of lost RLC SDUs. In addition, the NR RLC device may process the RLC PDU in the order of reception (in the order of arrival, regardless of the sequence number), and deliver the RLC PDU to the PDCP device out of order (out of order delivery), and in the case of segmentation, reassemble the segments stored in the buffer or received into the entire RLC PDU, and then process the RLC PDU and deliver it to the PDCP device. The NR RLC layer may not have a cascading function, and the cascading function may be performed by the NR MAC layer or replaced by a multiplexing function of the NR MAC layer.

[0126] In the above, the out-of-order delivery function of the NR RLC device refers to a function of delivering the RLC SDU received from the lower layer to the upper layer out of order, and may include a function of reassembling multiple RLC SDUs segmented from one RLC SDU and delivering the RLC SDUs when a segmented RLC SDU is received, or a function of storing the RLC SN or PDCP SN of the received RLC PDU and recording the lost RLC PDU by sorting the RLC PDUs.

[0127] NR MAC 1d-15 and 1d-30 can be connected to various NR RLC layer devices constituted in the terminal, and the main functions of NR MAC can include some of the following functions.

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

[0129] -Multiplexing and demultiplexing functions (MAC SDU multiplexing / demultiplexing)

[0130] -Scheduling information reporting function

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

[0132] - Priority handling function between logical channels (priority handling between logical channels of a UE)

[0133] - Priority handling function between UEs (priority handling between UEs with the help of dynamic scheduling)

[0134] -MBMS service identification function

[0135] -Transmission format selection function

[0136] - Fill function

[0137] The NR PHY layer 1d-20 or 1d-25 can encode and modulate the upper layer data channel into OFDM symbols and send the OFDM symbols through the radio channel, or demodulate the OFDM symbols received through the radio channel, and channel-decode and deliver the OFDM symbols to the upper layer.

[0138] In the following reference figures and proposed embodiments of the present disclosure, enhanced techniques for PSCell addition and change processes are considered, specifically, conditional PSCell addition and change (conditional PSCell change (CPC) and conditional PSCell addition (CPAC)) processes are considered. The present disclosure proposes a method capable of maintaining corresponding configurations and conditions, so that CPAC can be continuously triggered even after an SCG change is performed for a previously supported CPAC operation, without performing a configuration release on a candidate secondary node (SN) configured from a base station.

[0139] Figure 1E 2 is a diagram illustrating an overall operation of performing a conditional PSCell addition process in an LTE system or an NR system according to an embodiment of the present disclosure.

[0140] refer to Figure 1E, UE 1e-01 in the RRC connected state performs data transmission / reception and channel measurement / reporting operations according to the configuration of the connected master node (MN) / master base station / MN base station 1e-02. MN base station 1e-02 can identify the need to add SN / SN node / SN base station for UE 1e-01, and use SN nodes 1e-03 and 1e-04 that can be candidates to identify whether SN addition can be performed for UE 1e-01. The corresponding process can be performed through the SgNB addition request sending / receiving process (in operation 1e-10) and the SgNB addition request confirmation sending / receiving process (in operation 1e-15) between the MN base station 1e-02 and the corresponding SN nodes 1e-03 and 1e-04. In operation 1e-20, the MN base station 1e-02 may include the CPA-related configurations (conditions for CPA and SCG-related RRC configurations) received from the candidate SNs 1e-03 and 1e-04 to which SN addition is allowed in operation 1e-10 / 1e-15 in the RRC configuration message of the MN base station 1e-02, and send it to the UE 1e-01. According to an embodiment, in the case of EN-DC, the CPA-related configurations of the SNs 1e-03 and 1e-04 are encapsulated in an RRCConnectionReconfiguration message, and in the case of NE-DC and NR-DC, the CPA-related configurations of the SNs 1e-03 and 1e-04 are encapsulated in an RRCReconfiguration message, and it may be sent to the UE 1e-01. Reference Figure 1E, the case of NR-DC will be assumed and described. However, it is obvious to those skilled in the art that the embodiment can be similarly applied to EN-DC and NE-DC. As for the SN CPA-related configuration included in the RRC configuration, up to 8 SN CPA configurations can be provided by ConditionalReconfiguration as shown in Table 1 below. For reference, the corresponding configuration is the same as the maximum number of configurations related to MN conditional switching (CHO) and SN CPAC, and the base station can configure up to 8 configurations considering both MN CHO and SN CPAC. Among the SN CPAC-related configurations, condReconfigId means the index of the corresponding SN CPAC configuration, and the SN CPAC configuration corresponding to the corresponding condReconfigId may include the condition (condExecutionCond) of the SN CPA indicated by measId and condRRCReconfig including the SCG configuration to be applied after the UE performs SN CPA. The condition (CondExcutionCond) of SN CPA may include up to two trigger conditions, and may provide one RS type and up to two different trigger quantities (eg, RSRP and RSRQ, RSRP and SINR, etc.) as conditions.

[0141] [Table 1]

[0142]

[0143]

[0144] In operation 1e-25, UE 1e-01 may send an RRCReconfigurationComplete message to the MN base station 1e-02 in response to the received RRC configuration (including the configuration of the MN and SN, especially the CPA-related configuration). Then, when the CPA-related conditions received from the predetermined SN 1e-03 are met, UE 1e-01 may trigger the SN addition process of the corresponding SN 1e-03. That is, in operation 1e-30, UE 1e-01 may generate an MN RRCReconfigurationComplete message including an SN RRCReconfigurationComplete message for the SN 1e-03 for which the SN addition process is triggered (for the SN for which the CPA condition is met), and send it to the MN base station 1e-02. In operation 1e-35, the MN base station 1e-02 may send an SgNB reconfiguration completion message to the SN base station 1e-03 for which the corresponding CPA condition is satisfied, that is, the SN base station 1e-03 for which the UE 1e-01 performs SN addition, and notify the UE 1e-01 of the SN addition operation. In addition, in operation 1e-40, the MN base station 1e-02 may send an SgNB release request message indicating the release of the SCG configuration sent to the UE 1e-01 to the candidate SN base station 1e-04 to which the SN has not yet been added. In operation 1e-45, the corresponding candidate SN 1e-04 may send an SgNB release request confirmation to the MN base station 1e-02 in response to the message. According to the implementation manner, the processes in operations 1e-40 and 1e-45 may be omitted.

[0145] In operation 1e-50, UE 1e-01 may perform a random access procedure for adding an SN to SN 1e-03 for which CPA is triggered. This operation may be performed only when a security key needs to be updated, and may be omitted in other cases. In operation 1e-55, MN base station 1e-02 may send a sequence number (SN) status to SN base station 1e-03, and in operation 1e-60, a process for sending (forwarding) data from UPF 1e-05 to SN base station 1e-03 may be performed. In addition, in operation 1e-65, as an operation of path update, MN base station 1e-02 may send a PDU session resource change indicator to AMF 1e-06, in operation 1e-70, AMF 1e-06 and UPF 1e-05 may perform a bearer modification procedure, and in operation 1e-75, UPF 1e-05 may send a PDU packet including an end marker to MN base station 1e-02 to indicate a change of a previous bearer. In operation 1e-80, AMF 1e-06 may send a PDU session resource change identification message indicating that the PDU session resource change has been completed to the MN base station 1e-02.

[0146] Figure 1F is a diagram illustrating an overall operation of performing a conditional PSCell change procedure in an LTE system or an NR system according to an embodiment of the present disclosure.

[0147] refer to Figure 1F, UE 1f-01 in the RRC connected state performs data sending / receiving and channel measurement / reporting operations according to the configuration of the connected master node (MN) / master base station / MN base station 1f-02. MN base station 1f-02 can identify the need to change the current source SN base station 1f-03 for UE 1f-01 to other SN base stations 1f-04 and 1f-05, and use the SN nodes 1f-04 and 1f-05 that can be candidates to identify whether an SN change can be performed for UE 1f-01. The corresponding process can be performed through the SgNB add request sending / receiving process (in operation 1f-10) and the SgNB add request confirmation sending / receiving process (in operation 1f-15) between the MN base station 1f-02 and the corresponding SN nodes 1f-04 and 1f-05. In operation 1f-20, the MN base station 1f-02 may include the CPC-related configurations (CPC conditions and SCG-related RRC configurations) received from the candidate SNs 1f-04 and 1f-05 that are allowed to add and change SNs in operation 1f-10 / 1f-15 in the RRC configuration message of the MN base station 1f-02, and send it to the UE 1f-01. According to an embodiment, in the EN-DC case, the CPA-related configurations of the SNs 1f-04 and 1f-05 are encapsulated in the RRCConnectionReconfiguration message, and in the NE-DC and NR-DC cases, the CPC-related configurations of the SNs 1f-04 and 1f-05 are encapsulated in the RRCReconfiguration message, and it may be sent to the UE 1f-01. Reference Figure 1F, the case of NR-DC will be assumed and described. However, it is obvious to those skilled in the art that the embodiment can be similarly applied to EN-DC and NE-DC. As for the SN CPC-related configuration included in the RRC configuration, up to 8 SN CPC configurations can be provided by ConditionalReconfiguration as shown in Table 2 below. For reference, the corresponding configuration is the same as the maximum number of configurations related to MN CHO and SN CPC, and the base station can configure up to 8 configurations considering both MN CHO and SN CPC. Among the SN CPC-related configurations, condReconfigId means the index of the corresponding SN CPC configuration, and the SN CPC configuration corresponding to the corresponding condReconfigId may include the condition (condExecutionCond) of the SN CPC indicated by measId and condRRCReconfig including the SCG configuration to be applied after the UE executes the SN CPC. The condition (CondExcutionCond) of the SN CPC may include up to two trigger conditions, and one RS type and up to two different trigger quantities (e.g., RSRP and RSRQ, RSRP and SINR, etc.) may be provided as conditions.

[0148] [Table 2]

[0149]

[0150]

[0151] In operation 1f-25, UE 1f-01 may send an RRCReconfigurationComplete message to MN base station 1f-02 in response to the received RRC configuration (including the configuration of MN and SN, especially CPC-related configuration). In addition, in operation 1f-30, UE 1f-01 may indicate the data forwarding address to the source SN base station 1f-03. According to the embodiment, the corresponding operation may be omitted.

[0152] Then, when the CPC-related conditions received from the predetermined SN 1f-04 are met, UE 1f-01 can trigger the SN change process of the corresponding SN 1f-04.

[0153] That is, in operation 1f-35, UE 1f-01 may generate an MNRRCReconfigurationComplete message including an SN RRCReconfigurationComplete message for SN1f-04 (for which the CPC condition is satisfied) for which the SN change process is triggered, and send it to the MN base station 1f-02. In operation 1f-40, the MN base station 1f-02 may send an SgNB release request message requesting SCG configuration release to the source SN base station 1f-03, and in operation 1f-45, the source SN base station 1f-03 may respond to the request by sending an SgNB release request confirmation message to the MN base station 1f-02. In operation 1f-50, the MN base station 1f-02 may send an SgNB reconfiguration completion message to the target SN base station 1f-04 for which the corresponding CPC condition is satisfied, that is, UE 1f-01 performs an SN change to its target SN base station 1f-04, and notifies UE 1f-01 of the SN change operation. In addition, in operation 1f-55, the MN base station 1f-02 may send an SgNB release request message indicating the release of the SCG configuration sent to the UE 1f-01 to the candidate SN base station 1f-05 to which the SN has not yet been changed. In addition, in operation 1f-60, the corresponding candidate SN base station 1f-05 may send an SgNB release request confirmation to the MN base station 1f-02 in response to the message. Depending on the implementation, processes 1f-55 and 1f-60 may be omitted.

[0154] In operation 1f-65, UE 1f-01 may perform a random access procedure for SN change relative to the target SN base station 1f-04 for which CPC is triggered. This operation may be performed only in a case where a security key needs to be updated and may be omitted in other cases. In operation 1f-70, MN base station 1f-02 may receive a sequence number (SN) status from the source SN base station 1f-03, and in operation 1f-75, the received SN status may be sent to the target SN base station 1f-04. In operation 1f-80, MN base station 1f-02 may perform a process for sending (forwarding) data from UPF 1f-06 to the target SN base station 1f-04. In addition, in operation 1f-85, as an operation of path update, the MN base station 1f-02 may send a PDU session resource change indicator to AMF 1f-07, in operation 1f-90, AMF 1f-07 and UPF 1f-06 may perform a bearer modification process, and in operation 1f-95, UPF 1f-05 may send a PDU packet including an end marker to the MN base station 1f-02 to indicate the change of the previous bearer. In operation 1f-100, UPF 1f-06 may indicate a new path to the target SN base station 1f-04. In operation 1f-105, AMF 1f-07 may send a PDU session resource change identification message indicating that the PDU session resource change has been completed to the MN base station 1f-02. In operation 1f-110, the MN base station 1f-02 may instruct the source SN base station 1f-03 to release the UE context.

[0155] Figure 1G is a diagram illustrating an overall operation of continuously performing a conditional PSCell adding process according to the first embodiment of the present disclosure.

[0156] refer to Figure 1G , in operation 1g-10, UE 1g-01 performs an RRC connection establishment process with a master node (MN) / main base station / MN base station 1g-02, and performs RRC configuration. In operation 1g-15, UE 1g-01 and MN base station 1g-02 can send and receive UE capability request (UECapabilityEnquiry (UE capability query)) and UE capability information (UECapabilityInformation (UE capability information)) messages to request UE capabilities and send UE capability information. Through this process, MN base station 1g-02 can identify the capabilities of UE 1g-01. It is characterized in that the corresponding UE capabilities include an indicator indicating whether UE 1g-01 supports continuous CPAC. UE capabilities can be sent using one of the feature set methods for each UE, each frequency band, or each frequency band combination, and UE capabilities can be sent separately for CPA and CPC.

[0157] In operation 1g-20, the MN base station 1g-02 can identify the need to add an SN to the UE 1g-01, and use the SN nodes 1g-03 and 1g-04 that can be candidates to identify whether the SN addition can be performed for the UE 1g-01. The corresponding process can be performed through the SgNB addition request sending / receiving process (in operation 1g-20) and the SgNB addition request confirmation sending / receiving process (in operation 1g-25) between the MN base station 1g-02 and the corresponding SN nodes 1g-03 and 1g-04. According to an embodiment, content for identifying whether continuous CPAC application is possible can be added in the above process. That is, the continuous CPAC application identification indicator and the identification indicator may be included in the SgNB addition request and the SgNB addition request confirmation. Alternatively, the continuous CPAC application identification indicator and the identification indicator may be included in the RRC node-to-node message (CG-Config and CG-ConfigInfo) instead of the above-mentioned Xn message exchange process.

[0158] In operation 1g-30, the MN base station 1g-02 may include the CPAC-related configurations (CPAC conditions and SCG-related RRC configurations) received from the candidate SNs 1g-03 and 1g-04 that allow the UE 1g-01 to add the SN in operation 1g-20 / 1g-25 in an RRC configuration message and send it to the UE 1g-01. According to an embodiment, in the case of EN-DC, the CPAC-related configuration of the SN is encapsulated in an RRCConnectionReconfiguration message, and in the case of NE-DC and NR-DC, the CPAC-related configuration of the SN is encapsulated in an RRCReconfiguration message and it may be sent to the UE 1g-01. Reference Figure 1G, the case of NR-DC will be assumed and described. However, it is obvious to those skilled in the art that the embodiment can be similarly applied to EN-DC and NE-DC. As for the SN CPAC-related configuration included in the RRC configuration, up to 8 SN CPAC configurations can be provided by ConditionalReconfiguration as shown below. For reference, the corresponding configuration is the same as the maximum number of configurations related to MN conditional switching (CHO) and SN CPAC, and the base station can configure up to 8 configurations considering both MN CHO and SN CPAC. Among the SN CPAC-related configurations, condReconfigId means the index of the corresponding SN CPAC configuration, and the SN CPAC configuration corresponding to the corresponding condReconfigId may include the condition (condExecutionCond) of the SN CPAC indicated by measId and condRRCReconfig including the SCG configuration to be applied after the UE performs SN CPAC. The condition (CondExcutionCond) of SN CPA may include up to two trigger conditions, and may provide one RS type and up to two different trigger quantities (eg, RSRP and RSRQ, RSRP and SINR, etc.) as conditions.

[0159] In addition, when the base station 1g-02 sends CPAC-related configurations (conditions of SN CPAC, SCG configurations applied after performing SNCPAC, etc.) to the UE 1g-01, the base station 1g-02 may include an indicator indicating support for continuous CPAC operation in the corresponding CPAC operation (for example, the following subsequentCG-Change field) and send the indicator. The UE 1g-01 that receives the corresponding indicator may keep / store / maintain the relevant CPAC configuration even after the SCG changes. That is, the UE 1g-01 does not release the received CPAC configuration, continues to identify the stored CPAC conditions even after the SCG changes, and if met, triggers CPC and performs CPC operations from the previous PSCell to the target PSCell. The corresponding operation may continue until a separate release command for continuous CPAC operation is sent from the base station 1g-02. There may be various methods for notifying the base station 1g-02 that continuous CPAC operation is supported, and the present disclosure proposes the following method.

[0160] 1. Option 1: Method for notifying support for continuous CPAC and indicating to UE 1g-01 via RRC message

[0161] 1) Option 1-1: A method for notifying the CPAC configuration of all SNs provided by base station 1g-02 to commonly support continuous CPAC.

[0162] - Refer to Option 1-1 Signaling Method in Table 3 below (subsequentCG-Change-r18; ENUMERATE {enable})

[0163] - Signaled by adding a field for the corresponding information to the ConditionalReconfiguration-r16 IE and extending it, or by introducing a new field in another IE in MN RRCReconfiguration to indicate whether the corresponding operation is enabled.

[0164] -The corresponding field can also be used as whether to activate / deactivate continuous CPAC operation (e.g., enable / disable, activate / deactivate), and according to an embodiment, in the absence of the corresponding field signaling, it can indicate that the CPAC operation is deactivated.

[0165] - Signaling may be in the form of ENUMERATE {activate, deactivate}

[0166] 2) Option 1-2: A method for notifying each SN to which the CPAC configuration provided by the base station 1g-02 is individually applied of support for continuous CPAC.

[0167] - Refer to the signaling method of option 1-2 in Table 3 below (subsequent CG-Change-r18; ENUMERATED {reserved, unreserved})

[0168] -Signaled by adding a field for the corresponding information to CondRefigToAddMod-r16 IE and extending it, and indicating whether the corresponding operation is enabled. That is, the UE identifies whether continuous CPAC is applied to each CPAC configuration, and stores / keeps / maintains it according to the relevant configuration (does not release the corresponding configuration even after the SCG changes)

[0169] - Separate signaling indicating whether to activate / deactivate continuous CPAC operation may be used for all CPAC configurations except for the corresponding field, and the signaling introduced in Option 1-1 may be applied.

[0170] [Table 3]

[0171]

[0172]

[0173] 2. Option 2: Method for indicating continuous CPAC operation and updating application configuration via MAC CE signaling

[0174] -Introduction of MAC CE with new Logical Channel ID (LCID) or Extended LCID (eLCID)

[0175] - Includes a field indicating activation / deactivation of continuous CPAC operation (a method for applying the corresponding field to the entire CPAC configuration or to an individual CPAC configuration is possible). Fig. 1I The detailed MAC CE structure is shown in FIG.

[0176] - RRC signaling method that can be additionally applied to option 1 above

[0177] - To signal updates of continuous CPAC operation by reducing latency and signaling in case a change in whether SN CPAC operation is supported needs to be made based on inter-node RRC messages with the SN and negotiation over the Xn interface.

[0178] As described above, the above option 2 may be used in operation 1g-40, and may be omitted (repeating operations 1g-30 / 1g-35) in the case where the RRC configuration is replaced and used.

[0179] In operation 1g-35, UE 1g-01 may send an RRCReconfigurationComplete message to the MN base station 1g-02 in response to the received RRC configuration (including the configuration of the MN and SN, especially the CPAC-related configuration). Then, in the case where the CPAC-related conditions received from the predetermined SN 1g-03 are met, UE 1g-01 may trigger the SN addition process of the corresponding SN 1g-03. That is, in operation 1g-45, UE 1g-01 may generate an MNRRCReconfigurationComplete including an SN RRCReconfigurationComplete message for the SN for which the SN addition process is triggered (for which the CPA condition is met), and send it to the MN base station 1g-02. In operation 1g-50, the MN base station 1g-02 may send an SgNB reconfiguration completion message to the SN base station 1g-03 for which the corresponding CPA condition is satisfied, that is, the SN base station 1g-03 for which UE1g-01 performs SN addition, and notify the UE 1g-01 of the SN addition operation. In addition, in operation 1g-55, the MN base station 1g-02 may perform a process for identifying the validity of the CPAC configuration sent to the UE 1g-01 with respect to the candidate SN base station 1g-04 to which the SN has not yet been added, that is, in operation 1g-55, the MN base station 1g-02 may request the candidate SN base station 1g-04 whether the previously provided (continuous) CPAC configuration is valid even after the SCG is changed, or whether the previously provided (continuous) CPAC configuration needs to be updated. The corresponding message may be an SgNB update request message or another Xn message, or may be an RRC inter-node message. In operation 1g-60, each of the candidate SNs 1g-04 sends an SgNB update request confirmation or an RRC inter-node message including (continuous) CPAC configuration update information to the MN base station 1g-01 in response to the message. According to an embodiment, the processes in operations 1g-55 and 1g-60 may be omitted. In addition, Figure 1G The continuous CPAC operation that can be repeatedly performed thereafter is omitted, but UE 1g-01 can perform related operations (CPC triggering and CPC execution) by continuously applying the received CPAC configuration.

[0180] In operation 1g-65, UE 1g-01 may perform a random access procedure for adding an SN to SN 1g-03 for which CPA is triggered. This operation may be performed only in the case where a security key needs to be updated, and may be omitted in other cases. In operation 1g-70, MN base station 1g-02 may send a sequence number (SN) status to SN base station 1g-03, and in operation 1g-75, a process for sending (forwarding) data from UPF 1g-05 to SN base station 1g-03 may be performed. In addition, in operation 1g-80, as an operation of path update, MN base station 1g-02 may send a PDU session resource change indicator to AMF 1g-06, in operation 1g-85, AMF 1g-06 and UPF 1g-05 may perform a bearer modification procedure, and in operation 1g-90, UPF 1g-05 may send a PDU packet including an end marker to MN base station 1g-02 to indicate a change of a previous bearer. In operation 1g-95, AMF 1g-06 may send a PDU session resource change identification message to the MN base station 1g-02 indicating that the PDU session resource change has been completed.

[0181] Figure 1H is a diagram illustrating an overall operation of continuously performing a conditional PSCell change process according to an embodiment of the present disclosure.

[0182] refer to Figure 1H , in operation 1h-10, in the RRC connected state, UE 1h-01 and MN base station / MN node / main base station 1h-02 perform a process of requesting UE capabilities and sending UE capability information through UE capability request (UECapabilityEnquiry) and UE capability information (UECapabilityInformation) messages. Through this process, the MN base station 1h-02 can identify the capabilities of UE 1h-01. It is characterized in that the corresponding UE capabilities include an indicator indicating whether UE 1h-01 supports continuous CPAC. UE capabilities can be sent using one of the feature set methods for each UE, each frequency band, or each frequency band combination, and UE capabilities can be sent separately for CPA and CPC. In operation 1h-15, UE 1h-01 can receive RRC configuration from the MN base station 1h-02 and can be provided with a basic configuration. In the present disclosure Figure 1H In the illustrated embodiment, it is assumed that a dual connection (DC) is established with the source SN 1h-03 in the above operations.

[0183] In operation 1h-20, the MN base station 1h-02 can identify the need to change the SN for UE 1h-01, and use the SN nodes 1h-04 and 1h-05 that can be candidates to identify whether the SN change can be performed for UE 1h-01. The corresponding process can be performed through the SgNB add request sending / receiving process (in operation 1h-20) and the SgNB add request confirmation sending / receiving process (in operation 1h-25) between the MN base station 1h-02 and the corresponding SN nodes 1h-04 and 1h-05. According to an embodiment, content for identifying whether continuous CPAC application is possible can be added to the above process. That is, the continuous CPAC application identification indicator and the identification indicator may be included in the SgNB add request and the SgNB add request confirmation. Alternatively, the continuous CPAC application identification indicator and the identification indicator may be included in the RRC node-to-node message (CG-Config and CG-ConfigInfo) instead of the above-mentioned Xn message exchange process.

[0184] In operation 1h-30, the MN base station 1h-02 may include in the RRC configuration message the CPAC-related configurations (CPAC conditions and SCG-related RRC configurations) received from the candidate SNs 1h-04 and 1h-05 that allow the UE 1h-01 to change the SN in operation 1h-20 / 1h-25, and send it to the UE 1h-01. According to an embodiment, in the EN-DC case, the CPAC-related configuration of the SN is encapsulated in the RRCConnectionReconfiguration message, and in the NE-DC and NR-DC cases, the CPAC-related configuration of the SN is encapsulated in the RRCReconfiguration message, and it may be sent to the UE 1h-01. In the accompanying drawings, the NR-DC case will be assumed and described. However, it is obvious to those skilled in the art that the embodiment may be similarly applied to EN-DC and NE-DC. As for the SN CPAC-related configurations included in the RRC configuration, up to 8 SN CPAC configurations may be provided by ConditionalReconfiguration as shown below. For reference, the corresponding configuration is the same as the maximum number of configurations related to MNCHO and SN CPAC, and the base station can configure up to 8 configurations considering both MN CHO and SN CPAC. Among the SN CPAC related configurations, condReconfigId means the index of the corresponding SN CPAC configuration, and the SN CPAC configuration corresponding to the corresponding condReconfigId may include the condition (condExecutionCond) of the SNCPAC indicated by measId and condRRCReconfig including the SCG configuration to be applied after the UE executes SN CPAC. The condition (CondExcutionCond) of the SN CPA may include up to two trigger conditions, and one RS type and up to two different trigger quantities (e.g., RSRP and RSRQ, RSRP and SINR, etc.) may be provided as conditions.

[0185] In addition, when the base station 1h-02 sends CPAC-related configurations (conditions of SN CPAC, SCG configurations applied after executing SNCPAC, etc.) to UE 1h-01, the base station 1h-02 may include an indicator indicating support for continuous CPAC operation in the corresponding CPAC operation (for example, the following subsequentCG-Change field) and send the indicator. UE 1h-01 that receives the corresponding indicator may keep / store / maintain the relevant CPAC configuration even after the SCG changes. That is, UE1h-01 does not release the received CPAC configuration, continues to identify the stored CPAC conditions even after the SCG changes, and if met, triggers CPC and performs CPC operations from the previous PSCell to the target PSCell. The corresponding operation may continue until a separate release command for continuous CPAC operation is sent from the base station 1h-02. There may be various methods for notifying the base station 1h-02 that continuous CPAC operation is supported, and the present disclosure proposes the following method.

[0186] 1. Option 1: Method for notifying support for continuous CPAC via RRC message and indicating to UE 1h-01

[0187] 1) Option 1-1: A method for notifying the CPAC configuration of all SNs provided by the base station 1h-02 to jointly support continuous CPAC.

[0188] - Refer to Option 1-1 signaling method in Table 4 below (subsequent CG-Change-r18; ENUMERATE {Enable})

[0189] - Signaled by adding a field for the corresponding information to the ConditionalReconfiguration-r16 IE and extending it, or by introducing a new field in another IE in MN RRCReconfiguration to indicate whether the corresponding operation is enabled.

[0190] -The corresponding field can also be used as whether to activate / deactivate continuous CPAC operation (e.g., enable / disable, activate / deactivate), and according to an embodiment, in the absence of the corresponding field signaling, it can indicate that the CPAC operation is deactivated.

[0191] - Signaling may be in the form of ENUMERATE {activate, deactivate}

[0192] 2) Option 1-2: A method for notifying each SN to which the CPAC configuration provided by the base station 1h-02 is individually applied of support for continuous CPAC.

[0193] - Refer to the signaling method of option 1-2 in Table 4 below (subsequent CG-Change-r18; ENUMERATED {reserved, non-reserved})

[0194] -Signaling by adding a field for the corresponding information to the CondRefigToAddMod-r16 IE and extending it, and indicating whether the corresponding operation is enabled. That is, the UE 1h-01 identifies whether continuous CPAC is applied to each CPAC configuration, and stores / keeps / maintains it according to the relevant configuration (the corresponding configuration is not released even after the SCG changes).

[0195] - Separate signaling indicating whether to activate / deactivate continuous CPAC operation may be used for all CPAC configurations except for the corresponding field, and the signaling introduced in Option 1-1 may be applied.

[0196] [Table 4]

[0197]

[0198]

[0199] 2. Option 2: Method for indicating continuous CPAC operation and updating application configuration via MAC CE signaling

[0200] -Introduction of MAC CE with new LCID or eLCID

[0201] - Includes a field indicating activation / deactivation of continuous CPAC operation (a method for applying the corresponding field to the entire CPAC configuration or to an individual CPAC configuration is possible). Fig. 1I The detailed MAC CE structure is shown in FIG.

[0202] - RRC signaling method that can be additionally applied to option 1 above

[0203] - To signal updates of continuous CPAC operation by reducing latency and signaling in case a change in whether SN CPAC operation is supported needs to be made based on inter-node RRC messages with the SN and negotiation over the Xn interface.

[0204] In operation 1h-40, the MN base station 1h-01 may indicate the data forwarding address to the source SN base station 1h-03. Operation 1h-40 may be omitted. As described above, the above option 2 may be used in operation 1h-45 and may be omitted if the RRC configuration is replaced and used (repeat operations 1h-30 / 1h-35).

[0205] Thereafter, when the CPAC-related conditions received from the predetermined SN 1h-04 are met, the UE 1h-01 can trigger the SN change process of the corresponding SN 1h-04. That is, in operation 1h-50, the UE 1h-01 can generate an MN RRCReconfigurationComplete including an SNRRCReconfigurationComplete message for the SN whose SN change process is triggered (for the SN whose CPAC conditions are met), and send it to the MN base station 1h-02. In operation 1h-55, the MN base station 1h-02 can send an SgNB release request message requesting SCG configuration release to the source SN base station 1h-03, and in operation 1h-60, the source SN base station 1h-03 can respond to the request by sending an SgNB release request confirmation message to the MN base station 1h-01. In operation 1h-65, the MN base station 1h-02 may send an SgNB reconfiguration completion message to the target SN base station 1h-04 for which the corresponding CPAC condition is satisfied, that is, the UE 1h-01 performs an SN change to its target SN base station 1h-04, and notifies the UE 1h-01 of the SN change operation. In addition, in operation 1h-70, the MN base station 1h-02 may perform a process for identifying the validity of the CPAC configuration sent to the UE 1h-01 relative to the candidate SN base station 1h-05 in which the SN has not been changed. That is, in the above operation 1h-70, the MN base station 1h-02 may request the candidate SN base station 1h-05 whether the previously provided (continuous) CPAC configuration is valid even after the SCG change, or whether the previously provided (continuous) CPAC configuration needs to be updated. The corresponding message may be an SgNB update request message or another Xn message, or may be an RRC node-to-node message. In operation 1h-70, each of the candidate SNs 1h-05 sends an SgNB update request confirmation or an RRC node-to-node message including (continuous) CPAC configuration update information to the MN base station 1h-02 in response to the message. According to an embodiment, the processes in operations 1h-70 and 1h-75 may be omitted. In addition, Figure 1H The continuous CPAC operation that can be repeatedly performed thereafter is omitted, but UE 1h-01 can perform related operations (CPC triggering and CPC execution) by continuously applying the received CPAC configuration.

[0206] In operation 1h-80, UE 1h-01 may perform a random access procedure for changing the SN with respect to the target SN 1h-04 for which CPC is triggered. This operation may be performed only in a case where a security key needs to be updated, and may be omitted in other cases. In operation 1h-85, the MN base station 1h-02 may receive a sequence number (SN) status from the source SN base station 1h-03, and in operation 1h-90, may send the received SN status to the target SN base station 1h-04. In operation 1h-95, the MN base station 1h-02 may perform a process for sending (forwarding) data from the UPF 1h-06 to the SN base station 1h-04. In addition, in operation 1h-100, as an operation of path update, the MN base station 1h-02 may send a PDU session resource change indicator to the AMF 1h-07, in operation 1h-105, the AMF 1h-07 and the UPF 1h-06 may perform a bearer modification process, and in operation 1h-110, the UPF 1h-05 may send a PDU packet including an end marker to the MN base station 1h-02 to indicate the change of the previous bearer. In operation 1h-115, the UPF 1h-06 may indicate a new path to the target SN base station 1h-04. In operation 1h-120, the AMF 1h-07 may send a PDU session resource change identification message indicating that the PDU session resource change has been completed to the MN base station 1h-02. In operation 1h-125, the MN base station 1h-02 may instruct the source SN base station 1h-03 to release the UE context.

[0207] Fig. 1I is a diagram illustrating the structure of MAC CE signaling for continuously updating candidate SCG configuration to support conditional PSCell addition and change according to an embodiment of the present disclosure.

[0208] refer to Fig. 1I , the details of the MAC CE signaling structure and operation applied to the embodiments of the present disclosure will be described. Fig. 1I , but the same functionality can be performed in DCI. The activation index can be provided in RRC or MAC CE signaling, and in the DCI, the corresponding index can be activated or the entire CPAC activation / deactivation can be indicated.

[0209] As in Figure 1G and Figure 1H As described in the related embodiments, in the embodiments of the present disclosure, the CPAC configuration is delivered to the UE supporting continuous CPAC operation, and at the same time, signaling is required to indicate whether the corresponding configuration should be maintained / stored even after the SCG is changed. Figure 1G and Figure 1HIn the associated embodiment, a method for indicating it through RRC signaling has been proposed as an option 1 method, and in addition to the corresponding option 1, a method for dynamically updating the configuration to which the corresponding continuous CPAC configuration is applied through MAC CE signaling has been described as option 2. Similar to option 1, the MAC CE of option 2 can be accessed in the following two ways.

[0210] 1. Option 2-1 (1i-05): Method for notifying CPAC configuration of all SNs provided by a base station and jointly activating / deactivating continuous CPAC

[0211] - A / D field (1i-10): A field indicating that continuous CPAC is activated / deactivated together for all SNs to which CPAC provided by RRC configuration is applied.

[0212] -R field (1i-15): reserved bit

[0213] 2. Option 2-2 (1i-20): Method for notifying each SN to which the CPAC configuration provided by the base station is applied that continuous CPAC is individually activated / deactivated

[0214] -Pi field (1i-25): A field indicating that continuous CPAC is commonly activated / deactivated for each SN to which the CPAC provided by the RRC configuration is applied. The i in the Pi field corresponds to the CPAC configuration index (condReconfigId-r16) provided in the RRC configuration. The bitmap size is assumed to be 8, and may have an extended index or other value size thereafter.

[0215] - Indexes can be replaced with explicit IDs instead of bitmaps, and additional fields can be provided in addition to the index.

[0216] Figure 1J is a diagram illustrating a UE operation to which an embodiment of the present disclosure is applied according to an embodiment of the present disclosure, which embodies the UE operation when conditional PSCell addition and change are continuously applied.

[0217] refer to Figure 1J, in operation 1j-05, the RRC-connected UE may send the UE capability to the base station through the UE capability information (UECapabilityInformation) message according to the request (UECapabilityEnquiry) of the base station. The corresponding UE capability may include an indicator indicating whether the UE supports continuous CPAC. The UE capability may be delivered using one of the feature set methods for each UE, each frequency band, or each frequency band combination, and the UE capability may be sent separately for CPA and CPC. In operation 1j-10, the UE may receive an RRC (re) configuration from the base station, and the basic configuration for data transmission and reception may be provided in the corresponding configuration. In addition, the RRC configuration may include a CPAC configuration for multiple SNs and an indicator indicating the application of continuous CPAC. In operation 1j-15, the UE may additionally receive a MAC CE from the base station to update the activation / deactivation information of the SN for supporting continuous CPAC. The MAC CE operation may be omitted, and when the corresponding information does not exist, the UE may operate by applying the CPAC-related configuration configured via the RRC.

[0218] When the UE receives the RRC configuration and MAC CE signaling at operation 1j-20, if the conditions are met, in operation 1j-25, the UE can perform a change to a PSCell that meets the conditions while continuously identifying the CPAC trigger conditions included in the CPAC configuration. That is, the UE applies the SCG configuration information provided in the CPAC configuration, and in the case where random access is required for the corresponding PSCell, the random access is performed and the uplink synchronization is matched. The UE can perform operations for PSCell changes, and additionally store / maintain / maintain the CPAC configuration of the SN that provides the CPAC configuration. The storage / maintenance / maintenance of the CPAC-related configuration of the SN that provides the CPAC configuration can be updated according to the RRC configuration provided in operation 1j-10 and the MAC CE signaling in operation 1j-15. That is, the configuration information can be updated according to the most recently provided information. In operation 1j-30, the UE can continue to identify channel measurement values ​​and CPAC conditions based on the stored CPAC configuration of the SN that supports continuous CPAC operation after completing the change to the target PSCell, and perform CPAC operations. Thereafter, the UE may perform operations after operation 1j-10 or operation 1j-15 according to the base station signaling.

[0219] When the UE receives the RRC configuration and MAC CE signaling in operation 1j-20, in operation 1j-35, the UE continuously identifies the CPAC triggering condition included in the CPAC configuration. The UE may perform operations after operation 1j-10 or operation 1j-15 according to the base station signaling.

[0220] Figure 1K is a diagram illustrating a base station operation to which an embodiment of the present disclosure is applied according to an embodiment of the present disclosure, which embodies the base station operation when conditional PSCell addition and change are continuously applied.

[0221] refer to Figure 1K , in operation 1k-05, the base station may send a UE capability request (UECapabilityEnquiry) message to the UE to obtain UE capabilities, and thus receive UE capabilities from the UE through a UE capability information (UECapabilityInformation) message. The corresponding UE capabilities may include an indicator indicating whether the UE supports continuous CPAC. The UE capabilities may be delivered using one of the feature set methods for each UE, each frequency band, or each frequency band combination, and the UE capabilities may be sent separately for CPA and CPC. The base station may identify the corresponding UE capabilities and thereafter determine whether to indicate continuous CPAC operation via RRC configuration. In operation 1k-10, the base station may perform a negotiation with a SN that is a candidate for SN addition and change to identify whether CPAC support is supported and perform related configurations. In operation 1k-10, the base station identifies whether each SN supports continuous CPAC, and in operation 1k-15, the base station may transmit the CPAC-related configuration to the UE through RRC reconfiguration based on the identification. That is, an indicator indicating continuous CPAC operation according to the configuration provided by each SN may be provided to the UE together with the CPAC configuration.

[0222] In operation 1k-20, in response to the RRC reconfiguration of the SN configuration (CPAC configuration) that has been provided, the base station can receive an RRCReconfigurationComplete message from the UE (receive the SN RRC completion message included in the MN RRC message) and recognize that the PSCell change is complete. In operation 1k-25, the MN base station can identify whether there is maintenance and update of the (continuous) CPAC configuration of the SN that has been provided with the CPAC configuration. After negotiation with the SN node in operation 1k-25, in the case where the (continuous) CPAC configuration is updated, the base station can indicate the update to the UE through MAC CE. For detailed MAC CE operations, refer to Fig. 1I In addition, according to an embodiment, the RRC configuration in operation 1k-15 may be performed instead of the MAC CE signaling in operation 1k-30.

[0223] Figure 1L is a block diagram showing the internal structure of a UE according to an embodiment of the present disclosure.

[0224] refer to Figure 1L, the UE includes a radio frequency (RF) processor 1l-10, a baseband processor 1l-20, a storage device 1l-30 and a controller 1l-40.

[0225] The RF processor 11-10 performs functions such as signal band conversion and amplification to receive and transmit signals through a radio channel. That is, the RF processor 11-10 up-converts the baseband signal provided by the baseband processor 11-20 into an RF band signal, then transmits the signal through an antenna, and down-converts the RF band signal received through the antenna into a baseband signal. For example, the RF processor 11-10 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a digital-to-analog converter (DAC), an analog-to-digital converter (ADC), etc. Although Figure 1L One antenna is shown in the figure, but the terminal may include multiple antennas. In addition, the RF processor 11-10 may include multiple RF chains. In addition, the RF processor 11-10 can perform beamforming. For beamforming, the RF processor 11-10 can adjust the phase and amplitude of the signal sent / received through the antenna or antenna element. The RF processor can perform MIMO operations and can receive multiple layers when performing MIMO operations.

[0226] The baseband processor 11-20 performs a conversion function between a baseband signal and a bit string according to the physical layer protocol of the system. For example, when sending data, the baseband processor 11-20 performs encoding and modulation on the transmission bit string to generate a complex symbol. In addition, when receiving data, the baseband processor 11-20 performs demodulation and decoding on the baseband signal provided from the RF processor 11-10 to recover the received bit string. For example, when sending data, in the case of following the orthogonal frequency division multiplexing (OFDM) scheme, the baseband processor 11-20 performs encoding and modulation on the transmission bit string to generate a complex symbol, maps the complex symbol to a subcarrier, performs an inverse fast Fourier transform (IFFT) on the subcarrier, and inserts a cyclic prefix (CP) to generate an OFDM symbol. In addition, when receiving data, the baseband processor 11-20 separates the baseband signal provided by the RF processor 11-10 into OFDM symbols, recovers the signal mapped to the subcarrier by fast Fourier transform (FFT) calculation, and performs demodulation and decoding to recover the bit string.

[0227] As described above, the baseband processor 11-20 and the RF processor 11-10 are responsible for sending and receiving signals. Therefore, the baseband processor 11-20 and the RF processor 11-10 can be referred to as a transmitter, a receiver, a transceiver or a communication unit. In addition, at least one of the baseband processor 11-20 and the RF processor 11-10 may include a plurality of communication modules for supporting different radio access technologies. In addition, at least one of the baseband processor 11-20 and the RF processor 11-10 may include different communication modules for processing different frequency band signals. Examples of different radio access technologies include WLAN (e.g., IEEE 802.11) and cellular networks (e.g., LTE). Examples of different frequency bands may include ultra-high frequency (SHF) bands (e.g., 2.NRHz, NRhz) and millimeter wave bands (e.g., 60GHz).

[0228] The storage device 11-30 stores basic programs, application programs, and data such as configuration information for the operation of the terminal. Specifically, the storage device 11-30 can store information about a secondary access node with which the terminal performs radio communication using a secondary radio access technology. The storage device 11-30 provides the stored data in response to a request from the controller 11-40.

[0229] The controller 11-40 controls the overall operation of the terminal. For example, the controller 11-40 controls the baseband processor 11-20 and the RF processor 11-10 to send / receive signals. The controller 11-40 also writes data into the storage device 11-40 and reads data from the storage device 11-30. To achieve this, the controller 11-40 may include at least one processor 11-42. For example, the controller 11-40 may include a communication processor (CP) for controlling communication and an application processor (AP) for providing an upper layer such as an application.

[0230] Figure 1M is a block diagram showing the configuration of a base station according to an embodiment of the present disclosure.

[0231] refer to Figure 1M The base station is constructed to include an RF processor 1m-10, a baseband processor 1m-20, a backhaul communication unit 1m-30, a storage device 1m-40 and a controller 1m-50.

[0232] The RF processor 1m-10 performs functions such as signal band conversion and amplification to send signals through a radio channel. That is, the RF processor 1m-10 up-converts the baseband signal provided by the baseband processor 1m-20 into an RF band signal, and then sends the signal through the antenna, and down-converts the RF band signal received through the antenna into a baseband signal. For example, the RF processor 1m-10 may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, etc. Although Figure 1M One antenna is depicted in the figure, but the base station may include multiple antennas. In addition, the RF processor 1m-10 may include multiple RF chains. The RF processor 1m-10 can perform beamforming. For beamforming, the RF processor 1m-10 can adjust the phase and amplitude of the signal sent / received through the antenna or antenna elements. The RF processor 1m-10 can perform downlink MIMO operations to send signals on one or more layers.

[0233] The baseband processor 1m-20 performs the function of converting between the baseband signal and the bit string according to the physical layer protocol of the first radio access technology. For example, when sending data, the baseband processor 1m-20 performs encoding and modulation on the transmission bit string to generate complex symbols. When receiving data, the baseband processor 1m-20 also performs demodulation and decoding on the baseband signal provided from the RF processor 1m-10 to recover the received bit string. For example, when sending data, in accordance with the OFDM scheme, the baseband processor 1m-20 performs encoding and modulation on the transmission bit string to generate complex symbols, maps the complex symbols to subcarriers, performs IFFT calculations on the subcarriers, and inserts CPs to generate OFDM symbols. In addition, when receiving data, the baseband processor 1m-20 separates the baseband signal provided by the RF processor 1m-10 into OFDM symbols, recovers the signal mapped to the subcarriers through FFT calculations, and performs demodulation and decoding to recover the bit string. As described above, the baseband processor 1m-20 and the RF processor 1m-10 are responsible for sending and receiving signals. Therefore, the baseband processor 1m-20 and the RF processor 1m-10 can be called a transmitter, a receiver, a transceiver, a communication unit, or a wireless communication unit.

[0234] The backhaul communication unit 1m-30 provides an interface for communicating with other nodes in the network. That is, the backhaul communication unit 1m-30 converts a bit string to be sent from the base station to another node (e.g., a secondary base station, a core network, etc.) into a physical signal, and converts a physical signal received from another node into a bit string.

[0235] The storage device 1m-40 stores basic programs, applications, and data such as configuration information for the operation of the base station. Specifically, the storage device 1m-40 can store information about the bearers allocated to the connected terminals and the measurement results reported by the terminals. The storage device 1m-40 can also store information as a criterion for determining whether to enable or disable the multi-connectivity of the terminal. The storage device 1m-40 provides the stored data in response to a request from the controller 1m-50.

[0236] The controller 1m-50 controls the overall operation of the base station. For example, the controller 1m-50 sends and receives signals through the baseband processor 1m-20 and the RF processor 1m-10, or through the backhaul communication unit 1m-30. The controller 1m-50 also writes data to the storage device 1m-40 and reads data from the storage device 1m-40. To achieve this, the controller 1m-50 may include at least one processor 1M-52.

[0237] It should be noted that Figures 1A to 1M In the illustrated configuration diagram, the control / data signal transmission method, the operation process example, and the configuration diagram are not intended to limit the scope of the present disclosure. In other words, all components, entities, or operations described above should not be interpreted as necessary components for the implementation of the present disclosure, and can be implemented within the scope of not impairing the nature of the present disclosure, even if only some components are included.

[0238] The operations of the above network entity or terminal can be implemented by providing a memory device storing corresponding program codes to any component in the network entity or terminal device. That is, the controller of the network entity or terminal device can perform the above operations by reading out and executing the program codes stored in the memory device by a processor or a central processing unit (CPU).

[0239] The various components, modules, etc. of the network entities, base stations, or terminal devices described herein may be operated using hardware circuits (e.g., complementary metal oxide semiconductor-based logic circuits), firmware, software, and / or any combination of hardware, firmware, and / or software embodied in a machine-readable medium. For example, transistors, logic gates, and circuits (such as specialized semiconductors) may be used to embody various electrical structures and methods.

[0240] While the present disclosure has been shown and described with reference to various embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents.

Claims

1. A method performed by a terminal in a wireless communication system, the method comprising: receiving, from a base station, a first message including conditional reconfiguration information, the conditional reconfiguration information including configuration information of at least one candidate primary and secondary cell group (SCG) cell (PSCell), information about at least one execution condition of conditional PSCell addition (CPA) or conditional PSCell change (CPC) of the at least one candidate PSCell, and information indicating that the conditional reconfiguration information is maintained after the PSCell addition or the PSCell change; identifying a first PSCell if at least one execution condition for a first PSCell among the at least one candidate PSCell is satisfied for the CPA or CPC based on the conditional reconfiguration information; sending a second message for adding the first PSCell or for changing to the first PSCell to the base station; as well as The at least one execution condition of the at least one candidate PSCell is evaluated.

2. The method according to claim 1, wherein: The assessment also includes: identifying a second PSCell if at least one execution condition for a second PSCell among the at least one candidate PSCell is satisfied for the CPC based on the conditional reconfiguration information; and A third message for changing from the first PSCell to the second PSCell is sent to the base station.

3. The method according to claim 1, further comprising: The capability information of the terminal is sent to the base station, wherein the capability information of the terminal includes information indicating that the terminal supports maintaining the conditional reconfiguration information after a PSCell addition procedure or a PSCell change procedure is performed.

4. The method according to claim 1, wherein: The first message is a message for modifying a radio resource control (RRC) connection, and Wherein, information indicating that the conditional reconfiguration information is maintained after a PSCell addition or a PSCell change is configured for each of the at least one candidate PSCell.

5. A method performed by a first base station in a wireless communication system, the method comprising: Sending a first message including conditional reconfiguration information to a terminal, the conditional reconfiguration information including configuration information of at least one candidate primary and secondary cell group (SCG) cell (PSCell), information about at least one execution condition of conditional PSCell addition (CPA) or conditional PSCell change (CPC) of the at least one candidate PSCell, and information indicating that the conditional reconfiguration information is maintained after the PSCell addition or the PSCell change; receiving, from the terminal, a second message for addition of the first PSCell or for change to the first PSCell in a case where at least one execution condition for the first PSCell among the at least one candidate PSCell is satisfied for the CPA or CPC based on the conditional reconfiguration information; as well as sending a third message for adding the first PSCell or for changing to the first PSCell to the second base station of the first PSCell, Wherein the conditional reconfiguration information is maintained after addition of the first PSCell or change to the first PSCell.

6. The method according to claim 5, further comprising: In a case where at least one execution condition for a second PSCell among the at least one candidate PSCell is satisfied for CPC based on the conditional reconfiguration information, a fourth message for changing from the first PSCell to the second PSCell is received from the terminal.

7. The method according to claim 5, further comprising: Capability information of the terminal is received from the terminal, the capability information of the terminal including information indicating that the terminal supports maintaining the conditional reconfiguration information after a PSCell addition procedure or a PSCell change procedure is performed.

8. The method according to claim 5, wherein: The first message is a message for modifying a radio resource control (RRC) connection, and Wherein, information indicating that the conditional reconfiguration information is maintained after a PSCell addition or a PSCell change is configured for each of the at least one candidate PSCell.

9. A terminal in a wireless communication system, the terminal comprising: Transceiver; and A controller is coupled to the transceiver and is configured to: receiving, from a base station, a first message including conditional reconfiguration information, the conditional reconfiguration information including configuration information of at least one candidate primary and secondary cell group (SCG) cell (PSCell), information about at least one execution condition of a conditional PSCell addition (CPA) or a conditional PSCell change (CPC) of the at least one candidate PSCell, and information indicating that the conditional reconfiguration information is maintained after the PSCell addition or the PSCell change, identifying a first PSCell in a case where at least one execution condition for a first PSCell among the at least one candidate PSCell is satisfied for CPA or CPC based on the conditional reconfiguration information, sending a second message for addition of the first PSCell or for change to the first PSCell to the base station, and The at least one execution condition of the at least one candidate PSCell is evaluated.

10. The terminal according to claim 9, wherein: The controller is also configured to: identifying a second PSCell if at least one execution condition for a second PSCell among the at least one candidate PSCell is satisfied for the CPC based on the conditional reconfiguration information; as well as A third message for changing from the first PSCell to the second PSCell is sent to the base station.

11. The terminal according to claim 9, wherein: The controller is also configured to: The capability information of the terminal is sent to the base station, wherein the capability information of the terminal includes information indicating that the terminal supports maintaining the conditional reconfiguration information after a PSCell addition procedure or a PSCell change procedure is performed.

12. The terminal according to claim 9, wherein: The first message is a message for modifying a radio resource control (RRC) connection, and Wherein, information indicating that the conditional reconfiguration information is maintained after a PSCell addition or a PSCell change is configured for each of the at least one candidate PSCell.

13. A first base station in a wireless communication system, the first base station comprising: Transceiver; and A controller is coupled to the transceiver and is configured to: sending a first message including conditional reconfiguration information to a terminal, the conditional reconfiguration information including configuration information of at least one candidate primary and secondary cell group (SCG) cell (PSCell), information about at least one execution condition of conditional PSCell addition (CPA) or conditional PSCell change (CPC) of the at least one candidate PSCell, and information indicating that the conditional reconfiguration information is maintained after the PSCell addition or the PSCell change, receiving, from the terminal, a second message for addition of the first PSCell or for change to the first PSCell in a case where at least one execution condition for the first PSCell among the at least one candidate PSCell is satisfied for the CPA or CPC based on the conditional reconfiguration information, and sending a third message for adding the first PSCell or for changing to the first PSCell to the second base station of the first PSCell, Wherein the conditional reconfiguration information is maintained after addition of the first PSCell or change to the first PSCell.

14. The first base station according to claim 13, wherein: The controller is also configured to: In a case where at least one execution condition for a second PSCell among the at least one candidate PSCell is satisfied for CPC based on the conditional reconfiguration information, a fourth message for changing from the first PSCell to the second PSCell is received from the terminal.

15. The first base station according to claim 13, wherein: The controller is also configured to: receiving capability information of the terminal from the terminal, the capability information of the terminal including information indicating that the terminal supports maintaining the conditional reconfiguration information after a PSCell addition procedure or a PSCell change procedure is performed, The first message is a message for modifying a radio resource control (RRC) connection, and Wherein, information indicating that the conditional reconfiguration information is maintained after a PSCell addition or a PSCell change is configured for each of the at least one candidate PSCell.

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