Method and apparatus for managing conditional switching and conditional PSCELL replacement in wireless communication system

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. A method for a terminal in a wireless communication system according to one embodiment of the present disclosure comprises the steps of: receiving configuration information related to conditional switching from a source network node; in response to detecting a failure in a primary cell group (MCG), selecting a first cell; and determining the selected first cell as a target cell of a radio resource control (RRC) reconstruction procedure based on candidate cell information included in configuration information related to conditional handover.

Description

Technical Field

[0001] This technology relates to a method and apparatus for managing conditional switching and conditional PSCell changes of terminals in a mobile communication system. Background Technology

[0002] 5G mobile communication technology defines a wide frequency band, enabling high transmission rates and new services. It can be implemented not only in "sub-6GHz" bands such as 3.5GHz, but also in "above 6GHz" bands, including 28GHz and 39GHz, known as millimeter waves (mmWave). Furthermore, 6G mobile communication technology (referred to as "super 5G systems") is being considered in terahertz bands (e.g., the 95GHz to 3THz band) to achieve transmission rates fifty times faster than 5G and ultra-low latency one-tenth that of 5G.

[0003] At the outset of 5G mobile communication technology development, in order to support services and meet performance requirements associated with enhanced mobile broadband (eMBB), ultra-reliable low-latency communication (URLLC), and massive machine-type communication (mMTC), ongoing standardization efforts were underway regarding the following aspects: beamforming and massive MIMO for mitigating radio wave path loss and increasing radio wave transmission distance in millimeter waves; dynamic operation supporting parameter sets (e.g., operating multiple subcarrier spacings) and time slot formats for efficient utilization of millimeter wave resources; initial access technologies to support multi-beam transmission and broadband; the definition and operation of BWP (bandwidth portion); new channel coding methods such as LDPC (low-density parity-check) codes for large-volume data transmission and polar codes for highly reliable transmission of control information; L2 preprocessing; and network slicing for providing dedicated networks for specific services.

[0004] Currently, given the services that 5G mobile communication technology needs to support, there is ongoing discussion about improvements and performance enhancements to the initial 5G mobile communication technology. Furthermore, there is already physical layer standardization for technologies such as: V2X (Vehicle-to-Everything), used to assist autonomous vehicles in determining driving based on information about the vehicle's location and status transmitted by the vehicle and to enhance user convenience; NR-U (New Radio Unlicensed), designed to comply with various regulatory requirements related to unlicensed frequency bands; NR UE Power Saving; Non-Terrestrial Networks (NTN), as UE-satellite direct communication used to provide coverage in areas where communication with terrestrial networks is impossible; and positioning.

[0005] Furthermore, in the air interface architecture / protocol domain, there is ongoing standardization work on the following technologies: Industrial Internet of Things (IIoT) for supporting new services through interconnection and convergence with other industries; IAB (Integrated Access and Backhaul) for providing nodes for network service area extension by supporting wireless backhaul and access links in an integrated manner; mobility enhancements including conditional handover and DAPS (Dual Active Stack) handover; and two-step random access (two-step RACH for NR) for simplifying the random access process. In the system architecture / service domain, standardization is also underway on the following: 5G baseline architectures (e.g., service-based architectures or service-based interfaces) for combining Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies; and Mobile Edge Computing (MEC) for receiving services based on UE location.

[0006] With the commercialization of 5G mobile communication systems, the already exponentially growing number of connected devices will be connected to communication networks, thus necessitating enhanced functionality and performance of 5G mobile communication systems as well as integrated operation of connected devices. To this end, new research has been undertaken concerning extended reality (XR) for effectively supporting AR (Augmented Reality), VR (Virtual Reality), MR (Mixed Reality), etc.; 5G performance improvements and complexity reductions through the utilization of artificial intelligence (AI) and machine learning (ML); AI service support; metaverse service support; and drone communications.

[0007] Furthermore, such development of 5G mobile communication systems will serve as the foundation for not only the development of 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 MIMO, metamaterial-based lenses and antennas for improving terahertz band signal coverage, high-dimensional spatial multiplexing technologies utilizing OAM (orbital angular momentum), and RIS (reconfigurable smart surfaces), but also the development of the following: full-duplex technologies for improving the frequency efficiency of 6G mobile communication technology and enhancing system networks, AI-based communication technologies for system optimization by utilizing satellites and AI (artificial intelligence) from the design stage and internalizing end-to-end AI support functions, and next-generation distributed computing technologies that enable services with complexity exceeding the limitations of UE operational capabilities by utilizing ultra-high-performance communication and computing resources.

[0008] As stated above, as mobile communication systems evolve to provide a variety of services, a need arises for methods to effectively provide such services. Summary of the Invention

[0009] Technical issues

[0010] The disclosed embodiments are intended to provide a method and apparatus for effectively managing the mobility of terminals in a wireless communication system.

[0011] Technical solution

[0012] According to embodiments of this disclosure, a method for a terminal in a wireless communication system includes: sending a first indicator to a source network node, the first indicator indicating support for simultaneous configuration of conditional handover and conditional primary / secondary cell (PSCell) addition and change (CHO+CPAC configuration) when selecting a first target network node in a Radio Resource Control (RRC) reconstruction process; receiving a second indicator related to the CHO+CPAC configuration from the source network node; and selecting a first target network node in the RRC reconstruction process based on the second indicator in response to detecting a failure in the primary cell group (MCG).

[0013] According to embodiments of this disclosure, a method for a network node in a wireless communication system includes: receiving a first indicator from a terminal, the first indicator indicating support for simultaneous configuration of conditional handover and conditional primary / secondary cell (PSCell) addition and change (CHO+CPAC configuration) when selecting a first target network node in a Radio Resource Control (RRC) reconstruction process; and sending a second indicator related to the CHO+CPAC configuration to the terminal, wherein the second indicator is used to select a first target network node in the RRC reconstruction process in response to detecting a failure in the primary cell group (MCG).

[0014] According to embodiments of this disclosure, a terminal in a wireless communication system includes a transceiver and at least one processor, wherein the processor is configured to send a first indicator to a source network node, the first indicator indicating support for simultaneous configuration of conditional handover and conditional primary / secondary cell (PSCell) addition and change (CHO+CPAC configuration) when selecting a first target network node in the Radio Resource Control (RRC) reconstruction process; receive a second indicator related to the CHO+CPAC configuration from the source network node; and, in response to detecting a failure in the primary cell group (MCG), select a first target network node for the RRC reconstruction process based on the second indicator.

[0015] According to embodiments of the present disclosure, a network node in a wireless communication system includes a transceiver and at least one processor, wherein the processor is configured to receive a first indicator from a terminal indicating support for simultaneous configuration of conditional handover and conditional primary / secondary cell (PSCell) addition and change (CHO+CPAC configuration) when selecting a first target network node in a Radio Resource Control (RRC) reconstruction process, and to send a second indicator to the terminal related to the CHO+CPAC configuration, wherein the second indicator is used to select a first target network node in the RRC reconstruction process in response to the detection of a failure in the primary cell group (MCG).

[0016] Beneficial effects

[0017] This disclosure can improve service quality by applying configuration information used to resolve connection failures of terminals.

[0018] When a terminal experiences a failure in a primary cell group connection, this disclosure can enhance the quality of service by performing a connection to another PCell and PSCell without additional delay.

[0019] The effects that can be obtained from this disclosure are not limited to those described above, and other effects not mentioned will be clearly understood by those skilled in the art to which this disclosure pertains from the following description. Attached Figure Description

[0020] Figure 1 The structure of an LTE system according to an embodiment of this disclosure is shown.

[0021] Figure 2 The radio protocol structure of an LTE system according to an embodiment of the present disclosure is shown.

[0022] Figure 3 The structure of a next-generation mobile communication system according to an embodiment of the present disclosure is shown.

[0023] Figure 4 A radio protocol structure for a next-generation mobile communication system according to an embodiment of the present disclosure is shown.

[0024] Figure 5 This is a block diagram illustrating the internal structure of a terminal according to an embodiment of the present disclosure.

[0025] Figure 6 This is a block diagram illustrating the configuration of an NR base station according to an embodiment of the present disclosure.

[0026] Figure 7 Configuration information according to an embodiment of this disclosure is shown.

[0027] Figure 8The operational sequence of the terminal and network according to embodiments of this disclosure is shown.

[0028] Figure 9 The operation of a terminal according to an embodiment of the present disclosure is illustrated. Detailed Implementation

[0029] The operating principles of this disclosure are described below with reference to the accompanying drawings. Detailed descriptions of known functions or configurations may be omitted when it is determined that the subject matter of the invention is unclear. The terminology used herein is defined in view of the functions in this disclosure and may be replaced with other terms depending on the intent or practice of the user or operator. Therefore, the terminology should be defined based on the entire disclosure.

[0030] As used herein, each of the phrases such as “A / B,” “A or B,” “at least one of A and B,” “at least one of A or B,” “A, B or C,” “at least one of A, B and C,” and “at least one of A, B or C” can include all possible combinations of the items listed together in the corresponding phrase. As used herein, terms such as “first” and “second” or “first” and “second” can be used simply to distinguish the corresponding component from another component and do not limit the components in other respects (e.g., importance or order).

[0031] As used herein, for ease of description, terms for identifying access nodes, network entities, messages, interfaces between network entities, and various types of identification information are provided as examples. Therefore, this disclosure is not limited to these terms, and these terms may be replaced by other terms representing objects having equivalent technical concepts.

[0032] In the following description, a base station can be an entity that allocates resources to a terminal, and can be at least one of a gNode B, eNode B, Node B, base station (BS), radio access unit, base station controller, or node on a network. A terminal can include a UE (User Equipment), MS (Mobile Station), cellular phone, smartphone, computer, or multimedia system capable of performing communication functions. In this disclosure, downlink (DL) refers to the radio transmission path of a signal from the base station to the terminal, and uplink (UL) refers to the radio transmission path of a signal from the terminal to the base station. Although LTE or LTE-A systems may be described as examples below, embodiments can be applied to other communication systems with similar technical backgrounds or channel modes. For example, 5G mobile communication technologies (5G, New Radio, NR) developed after LTE-A can be included in systems to which embodiments of this disclosure apply, and 5G below can be a concept encompassing legacy LTE, LTE-A, and other similar services.

[0033] Furthermore, it will be clear to those skilled in the art that embodiments can be modified without significantly departing from the scope of the invention, and such modifications can be applied to other communication systems. In this context, it should be understood that each block of the process flowchart and combinations of blocks in the flowchart can be executed by computer program instructions.

[0034] Because computer program instructions can be incorporated in the processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus, the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate means for performing functions associated with blocks in each flowchart. Because the computer program instructions can be stored in a computer-usable or computer-readable storage medium that is oriented toward the computer or other programmable data processing apparatus to implement functions in a specified manner, the instructions stored in the computer-usable or computer-readable storage medium can produce an article including instruction means for performing functions associated with blocks in each flowchart. Because the computer program instructions can be incorporated in a computer or other programmable data processing apparatus, the instructions that generate a process to be executed by the computer as a series of operational steps are executed on the computer or other programmable data processing apparatus, and operating the computer or other programmable data processing apparatus can provide steps for performing functions described in conjunction with blocks in each flowchart.

[0035] Furthermore, each box may represent a module, segment, or portion of code comprising one or more executable instructions for performing a specified logical function. It should also be noted that in some alternative embodiments, the functions mentioned in a box may occur in different orders. For example, depending on the respective function, two consecutively shown boxes may be executed substantially simultaneously or in reverse order. As used herein, the term "unit" refers to a software element or hardware element, such as a field-programmable gate array (FPGA) or application-specific integrated circuit (ASIC). A unit may serve a specific function. However, a "unit" is not limited to software or hardware. A "unit" may be configured in a storage medium that can be addressed or configured to execute one or more processors. Thus, by way of example, a "unit" includes elements such as software elements, object-oriented software elements, class elements, and task elements, processes, functions, attributes, procedures, subroutines, program code segments, drivers, firmware, microcode, circuits, data, databases, data schemas, tables, arrays, and variables. The functionality provided within components and "units" may be combined into a smaller number of components and "units," or further divided into additional components and "units." Furthermore, components and "units" may be implemented as one or more CPUs in an execution device or secure multimedia card. According to an embodiment, "...unit" may include one or more processors.

[0036] For ease of description, this document uses the terms and names defined in the current communication standards, specifically the 3GPP 5G and NR standards. However, this disclosure is not limited to these terms and names and can be equally applied to wireless communication networks conforming to other standards. For example, this disclosure can be applied to 3GPP GS / NR (the fifth-generation mobile communication standard).

[0037] Figure 1 This is a view illustrating the structure of an LTE system according to an embodiment of the present disclosure.

[0038] refer to Figure 1 As shown in the figure, the radio access network of an LTE system may include next-generation base stations (eNBs, Node Bs, or base stations) 105, 110, 115, and 120, a Mobility Management Entity (MME) 105, and a Service Gateway (S-GW) 130. User equipment (UEs or terminals) 135 can access external networks through eNBs 105 to 120 and S-GW 130.

[0039] Figure 1 The eNBs 105 to 120 can correspond to Node B in a traditional Universal Mobile Telecommunications System (UMTS) system. The eNB connects to the UE 135 via radio channels and plays a more complex role than a traditional Node B. In LTE systems, all user services, including real-time services such as Voice over IP (VoIP) via the Internet Protocol, can be served through shared channels. Therefore, equipment is needed to perform scheduling by collecting state information such as the UE's buffer state, available transmission power state, and channel state, and eNBs 105, 110, 115, and 120 can play this role. One eNB can typically control multiple cells. For example, an LTE system can use Orthogonal Frequency Division Multiplexing (OFDM) as the radio access technology on a 20MHz bandwidth to achieve a transmission speed of 100Mbps. Furthermore, the system can apply Adaptive Modulation and Coding (AMC), which determines the modulation scheme and channel coding rate based on the terminal's channel state. The S-GW 130 is the device that provides data bearers and can generate or remove data bearers under the control of the MME 125. The MME is a device responsible for various control functions and mobility management functions of the UE, and can connect to multiple base stations.

[0040] Figure 2 This is a view illustrating the radio protocol structure of a conventional LTE system according to an embodiment of the present disclosure.

[0041] refer to Figure 2The radio protocols of an LTE system can include Packet Data Convergence Protocol (PDCP) 205 and 240, Radio Link Control (RLC) 210 and 235, and Media Access Control (MAC) 215 and 230 in the terminal and eNB, respectively. PDCP is responsible for IP header compression / reconstruction. The main functions of PDCP can be summarized as follows.

[0042] - Header compression and decompression (ROHC only)

[0043] -Transmission of user data

[0044] - Sequential transfer of upper-layer PDUs during PDCP reconstruction in RLC AM

[0045] - For split bearers in the DC (RLC AM only), PDCP PDU routing for transmission and PDCP PDU reordering for reception.

[0046] - Repeated detection of lower-level SDUs during PDCP reconstruction of RLC AM

[0047] - Retransmission of PDCP SDUs during handover, and for split bearers in the DC, retransmission of PDCP PDUs during PDCP data recovery, for RLC AM.

[0048] - Encryption and decryption

[0049] - Timer-based SDU dropping in the uplink

[0050] Radio Link Control (RLC) 2-10 and 2-35 can reconfigure PDCP Packet Data Units (PDUs) to the appropriate size and perform ARQ operations. The main functions of the RLC can be summarized as follows.

[0051] -Transmission of upper-layer PDUs

[0052] - Error correction via ARQ (for AM data transmission only)

[0053] - Cascading, segmentation, and reassembly of RLC SDUs (for UM and AM data transfer only)

[0054] - Resegmentation of RLC data PDUs (for AM data transmission only)

[0055] - Reordering of RLC data PDUs (for UM and AM data transfer only)

[0056] - Duplicate detection (only for UM and AM data transfers)

[0057] - Protocol error detection (for AM data transmission only)

[0058] -RLC SDU discard (only for UM and AM data transfer)

[0059] -RLC Reconstruction

[0060] MAC 215 and 230 can connect to several RLC layer devices configured in a single terminal, and can multiplex RLC PDUs into MAC PDUs and demultiplex RLC PDUs from MAC PDUs. The main functions of the MAC can be summarized as follows.

[0061] Mapping between logical channels and transport channels

[0062] - Multiplexing MAC SDUs belonging to one or different logical channels into a transport block (TB) passed to the physical layer on the transport channel / Demultiplexing a transport block (TB) transmitted from the physical layer on the transport channel

[0063] - Scheduling Information Report

[0064] - Error correction via HARQ

[0065] Priority processing between logical channels of a UE

[0066] - Priority handling among dynamically scheduled UEs

[0067] -MBMS service identifier

[0068] -Transmission format selection

[0069] -filling

[0070] Physical layer (PHY) 220 and 225 can encode and modulate higher-layer data channels into OFDM symbols, transmit OFDM symbols through radio channels, or demodulate OFDM symbols received through radio channels, decode the channels, and transmit them to higher layers.

[0071] Figure 3 This is a view illustrating the structure of a next-generation mobile communication system according to an embodiment of the present disclosure.

[0072] refer to Figure 3 The radio access network for a next-generation mobile communication system (hereinafter referred to as NR or 5G) may include a next-generation base station (new radio node B, hereinafter referred to as NR gNB or NR base station) 310 and a next-generation radio core network (NR CN) 305. Next-generation radio user equipment (hereinafter, NR UE or terminal) 315 can access external networks through NR gNB 310 and NRCN 305.

[0073] exist Figure 3In this context, the NR gNB 310 corresponds to the evolved Node B (eNB) in a traditional LTE system. The NR gNB connects to the NR UE 315 via a radio channel and can provide superior service compared to a traditional Node B. In next-generation mobile communication systems, all user services can be served through a shared channel. Therefore, equipment is needed to perform scheduling by collecting state information such as the UE's buffer state, available transmission power state, and channel state, and the NR gNB 310 can handle this scheduling. One NR gNB can control multiple cells.

[0074] In next-generation mobile communication systems, bandwidths exceeding the conventional maximum bandwidth can be used to achieve ultra-high-speed data transmission on traditional LTE. Furthermore, orthogonal frequency division multiplexing (OFDM) can be used as a radio access technology to additionally apply beamforming techniques. Additionally, adaptive modulation and coding (hereinafter referred to as AMC) can be applied to determine the modulation scheme and channel coding rate based on the terminal's channel state.

[0075] The NR CN 305 can perform functions such as mobility support, bearer configuration, and QoS configuration. The NR CN 305 is responsible for mobility management functions and various control functions for the UE, and can connect to multiple base stations. Furthermore, next-generation mobile communication systems can link with LTE systems. The NR CN 305 can connect to the MME 325 via a network interface. The MME 325 can connect to the eNB 330, which acts as an LTE base station.

[0076] Meanwhile, an NR gNB 310 can typically transmit and receive multiple carriers over several frequency bandwidths. For example, when transmitting a carrier with a forward center frequency f1 and a carrier with a forward center frequency f3 from the base station, an NR UE 315 with carrier aggregation capability can transmit / receive data simultaneously through multiple carriers.

[0077] For NR UE 315 with carrier aggregation capability, NR gNB 310 can increase the transmission rate of NR UE 315 by allocating more carriers according to actual conditions. As mentioned above, aggregating the forward and uplink carriers transmitted and received by a base station is called "intra-base station carrier aggregation". However, in some cases, with Figure 3 The differences shown may require aggregating forward and backward carriers sent and received by different base stations.

[0078] When NR gNB 310 transmits / receives a carrier with center frequency f1 and another base station transmits / receives a carrier with center frequency f2, if NR UE 315 aggregates (combines) a carrier with forward center frequency f1 and a carrier with forward center frequency f2, this results in a terminal aggregating carriers transmitted / received from two or more base stations, and in embodiments of this disclosure, this is referred to as "inter-base station carrier aggregation (or inter-base station CA)".

[0079] In embodiments of this disclosure, inter-base station carrier aggregation is referred to as dual connectivity (DC) (hereinafter referred to as "DC"). For example, configuring DC may mean configuring inter-base station carrier aggregation, configuring one or more cell groups, configuring secondary cell groups (SCGs) (hereinafter referred to as "SCGs"), configuring at least one secondary cell (SCell) (hereinafter referred to as "SCell") controlled by a base station other than the serving base station, configuring a pSCell (primary SCell), configuring a MAC entity for the serving base station, and configuring two MAC entities at the terminal.

[0080] In addition, the terms frequently used in describing the embodiments of the present invention are briefly described below.

[0081] In the traditional sense, when a forward carrier transmitted from a base station and an uplink carrier received by the base station constitute a cell, carrier aggregation can be understood as the UE transmitting data simultaneously through multiple cells. Here, the maximum transmission speed and the number of aggregated carriers are positively correlated.

[0082] In the following embodiments of the invention, a terminal that receives data via any forward carrier or transmits data via any uplink carrier has the same meaning as a terminal that transmits / receives data using control channels and data channels provided by a cell corresponding to the center frequency and band characterizing the carrier. In embodiments of this disclosure, carrier aggregation is specifically referred to as "configuring multiple serving cells," and terms such as primary serving cell (hereinafter referred to as PCell), secondary serving cell (hereinafter referred to as SCell), or active serving cell are used. In embodiments of the invention, terms such as carrier, component carrier, and serving cell are used interchangeably.

[0083] In embodiments of the present invention, the set of serving cells controlled by the same base station is defined as a cell group or carrier group (CG) (hereinafter referred to as "CG"). The cell group is further divided into a master cell group (MCG) (hereinafter referred to as "MCG") and a secondary cell group (SCG) (hereinafter referred to as "SCG").

[0084] MCG refers to the set of serving cells controlled by a base station (hereinafter referred to as the primary base station) that controls one primary cell (PCell) and up to N secondary cells (SCells). SCG refers to the set of serving cells controlled by a base station (hereinafter referred to as the secondary base station) that controls one primary and secondary cell (PSCell) and up to N SCells. When establishing a corresponding serving cell, the base station notifies the terminal whether a specific serving cell belongs to an MCG or an SCG.

[0085] A terminal can be configured with one MCG and one or more SCGs. In the embodiments of the present invention, for ease of description, only the case of configuring one SCG is considered. However, the present invention can be applied without any modifications even when two or more SCGs are configured.

[0086] There are some differences between PCell and SCell. For example, PCell is always active, but SCell repeatedly goes through active and deactivated states according to instructions from the base station. Terminal mobility is controlled centrally by the PCell, and the SCell can be understood as an additional serving cell used for data communication. In embodiments of the present invention, PCell and SCell may refer to the PCell and SCell defined in 3GPP TS 36.331 or TS 36.321.

[0087] In the following description, for clarity, other terms may be used instead of MCG and SCG. For example, terms such as primary set and secondary set, or primary carrier group and secondary carrier group may be used. Even where the terms differ, it should be noted that only the terminology used differs; the meaning is the same.

[0088] Figure 4 This is a view illustrating the structure of a radio protocol for a next-generation mobile communication system according to an embodiment of the present disclosure.

[0089] refer to Figure 4 The radio protocol of the next-generation mobile communication system consists of NR Service Data Adaptation Protocol (SDAP) 401 and 445, NR PDCP 405 and 440, NR RLC 410 and 435, NR MAC 415 and 430 and NRPHY 420 and 425 respectively at the terminal and NR base station.

[0090] The main functions of NR SDAP 401 and 445 may include some of the following functions.

[0091] -Transmission of user plane data

[0092] - Mapping between QoS flows and DRB for both DL and UL

[0093] - Mark QoS flow IDs in DL and UL groups

[0094] - UL SDAP PDU reflection QoS flow to DRB mapping.

[0095] For SDAP layer devices, Radio Resource Control (RRC) messages can be used to configure whether the terminal uses the SDAP layer entity header or SDAP layer entity functionality for each PDCP layer entity, each bearer, or each logical channel. When configuring the SDAP header, the terminal can indicate this via a 1-bit Non-Access Stratum (NAS) Quality of Service (QoS) reflection configuration indicator (NAS reflected QoS) and an 1-bit Access Stratum (AS) QoS reflection configuration indicator (AS reflected QoS) in the SDAP header, allowing the terminal to update or reconfigure the mapping information regarding uplink and downlink data bearers and QoS flows. The SDAP header can include QoS flow ID information indicating QoS. QoS information can be used as data prioritization or scheduling information to seamlessly support service.

[0096] The main functions of NR PDCP 405 and 440 may include some of the following functions.

[0097] - Header compression and decompression (ROHC only)

[0098] -Transmission of user data

[0099] - Sequential transmission of upper-layer PDUs

[0100] -Disordered transmission of upper-layer PDUs

[0101] - Reordering of received PDCP PDUs

[0102] -Duplicate detection of lower-level SDUs

[0103] -PDCP SDU retransmission

[0104] - Encryption and decryption

[0105] - Timer-based SDU dropping in the uplink

[0106] In the above description, the reordering function of an NR PDCP device can refer to the function of reordering PDCP PDUs received from lower layers in sequence based on the PDCP sequence number (SN). Reordering by an NR PDCP device may include transmitting data to higher layers in the reordered order or immediately regardless of the order, recording lost PDCP PDUs through reordering, reporting the status of lost PDCP PDUs to the transmitting part, and requesting retransmission of lost PDCP PDUs.

[0107] The main functions of NR RLC 410 and 435 may include some of the following functions.

[0108] -Transmission of upper-layer PDUs

[0109] - Sequential transmission of upper-layer PDUs

[0110] -Disordered transmission of upper-layer PDUs

[0111] - Error correction via ARQ

[0112] Cascading, segmentation, and reassembly of RLC SDUs

[0113] - Resegmentation of RLC data PDUs

[0114] - RLC data PDU reordering

[0115] -Duplicate detection

[0116] -Protocol error detection

[0117] -RLC SDU discard

[0118] -RLC Reconstruction

[0119] In this context, the sequential delivery function of an NR RLC device can refer to the function of sequentially transmitting RLC SDUs received from a lower layer to an upper layer. When receiving a raw RLC SDU that has been divided into multiple RLC SDUs, the sequential delivery function of an NR RLC device can include the function of reassembling and transmitting them.

[0120] The sequential transmission function of the NR RLC device may include the function of reordering the received RLC PDUs based on the RLC sequence number (SN) or PDCP sequence number (SN), the function of recording lost RLC PDUs by reordering the sequence, the function of reporting the status of lost RLC PDUs to the transmitting side, and the function of requesting retransmission of lost RLC PDUs.

[0121] The sequential delivery function of NR RLC devices can include the ability to sequentially deliver only the RLC SDUs up to the lost RLC SDU to the upper layer when a lost RLC SDU exists.

[0122] The sequential delivery function of an NR RLC device may include the function of sequentially delivering all RLC SDUs received before the timer starts to the upper layer, even if a lost RLC SDU exists and a predetermined timer expires.

[0123] The sequential delivery function of NR RLC devices can include the ability to sequentially deliver all RLC SDUs received so far to the upper layer, even if a pre-defined timer expires, even if there are lost RLC SDUs.

[0124] NR RLC devices can process RLC PDUs in the order they are received, regardless of the sequence number (out-of-order delivery), and pass them to NR PDCP devices.

[0125] When an NR RLC device receives a segment, it can receive segments stored in a buffer or to be received later, reconstruct them into a complete RLC PDU, and then pass it to an NR PDCP device.

[0126] The NR RLC layer may not include cascading functionality, and it can be implemented in the NR MAC layer or replaced by multiplexed functionality of the NR MAC layer.

[0127] In this context, the out-of-order delivery function of an NR RLC device can refer to the function of immediately transmitting RLC SDUs received from a lower layer to an upper layer regardless of their order. The out-of-order delivery function of an NR RLC device can include the function of reassembling and delivering a raw RLC SDU that has been divided into multiple RLC SDUs upon receipt. The out-of-order delivery function of an NR RLC device can also include the function of storing the RLC SN or PDCP SN of received RLC PDUs and recording lost RLC PDUs by reordering them.

[0128] NR MACs 415 and 430 can connect to several NR RLC layer devices configured in a UE, and the main functions of the NR MAC can include some of the following functions.

[0129] Mapping between logical channels and transport channels

[0130] - MAC SDU multiplexing / demultiplexing

[0131] - Scheduling Information Report

[0132] - Error correction via HARQ

[0133] Priority processing between logical channels of a UE

[0134] - Priority handling among dynamically scheduled UEs

[0135] -MBMS service identifier

[0136] -Transmission format selection

[0137] -filling

[0138] NR PHY layers 420 and 425 can encode and modulate higher-layer data channels into OFDM symbols, transmit OFDM symbols via wireless channels, or demodulate OFDM symbols received via wireless channels, decode the channels, and transmit them to higher layers.

[0139] Figure 5 This is a block diagram illustrating the structure of a terminal according to an embodiment.

[0140] Referring to the accompanying drawings, the terminal may include a transceiver 500, a storage unit 530, and a controller 540. The transceiver 500 may include an RF processing unit 510 and a baseband processing unit 520. The transceiver 500 may be referred to as a communication unit. The controller 540 may include a dual-connectivity processing unit 542.

[0141] The RF processing unit 510 included in transceiver 500 can perform functions for transmitting / receiving signals via a radio channel, such as signal band conversion and amplification. The RF processing unit 510 can up-convert a baseband signal provided from baseband processing unit 520 into an RF band signal, then transmit that signal through an antenna, and down-convert an RF band signal received through the antenna back into a baseband signal. For example, the RF processor 510 may include, for example, transmit filters, receive filters, amplifiers, mixers, oscillators, digital-to-analog converters (DACs), and analog-to-digital converters (ADCs). Only one antenna is shown in the figures, but the UE may include multiple antennas. Furthermore, the RF processing unit 510 may include multiple RF chains. Additionally, the RF processing unit 510 can perform beamforming. For beamforming, the RF processing unit 510 can adjust the phase and amplitude of each signal transmitted and received through multiple antennas or antenna elements. Furthermore, the RF processing unit can perform MIMO and can receive multiple layers when performing MIMO operation.

[0142] The baseband processing unit 520 included in the transceiver 500 performs conversion functions between baseband signals and bitstreams according to the system's physical layer specifications. For example, when transmitting data, the baseband processing unit 520 can generate complex symbols by encoding and modulating the transmitted bitstream. Furthermore, when receiving data, the baseband processing unit 520 can recover the received bitstream by demodulating and decoding the baseband signal provided from the RF processing unit 510. For example, when following an Orthogonal Frequency Division Multiplexing (OFDM) scheme, when transmitting data, the baseband processing unit 520 can generate complex symbols by encoding and modulating the transmitted bitstream, map the complex symbols to subcarriers, and then configure the OFDM symbols through inverse Fast Fourier Transform (IFFT) operations and cyclic prefix (CP) insertion. Furthermore, when receiving data, the baseband processing unit 520 can divide the baseband signal provided from the RF processing unit 510 based on OFDM symbols, recover the signals mapped to subcarriers through Fast Fourier Transform (FFT), and then recover the received bitstream through demodulation and decoding.

[0143] Baseband processing unit 5-20 and RF processing unit 5-10 can transmit / receive signals as described above. Furthermore, at least one of baseband processing unit 520 and RF processing unit 510 may include multiple communication modules to support various different radio access technologies. Additionally, at least one of baseband processing unit 520 and RF processing unit 510 may include different communication modules to process signals in different frequency bands. For example, different radio access technologies may include wireless LAN (e.g., IEEE 802.11), cellular networks (e.g., LTE), etc. Furthermore, different frequency bands may include ultra-high frequency (SHF) bands (e.g., 2.0 NRHz or NRHz) or millimeter wave (mmWave) bands (e.g., 60 GHz).

[0144] Storage unit 530 can store data such as basic programs, application programs, and configuration information for terminal operation. Specifically, storage unit 530 can store information related to a second access node performing wireless communication using a second radio access technology. Furthermore, storage unit 530 can provide stored data upon request from controller 540.

[0145] The controller 540 can control the overall operation of the terminal. For example, the controller 540 can send / receive signals through the baseband processing unit 520 and the RF processing unit 510. Furthermore, the controller 540 can write data to / read data from the storage unit 530. For this purpose, the controller 540 may include at least one processor. For example, the controller 540 may include a communication processor (CP) that performs control for communication and an application processor (AP) that controls upper layers such as applications.

[0146] Figure 6 This is a block diagram illustrating the configuration of an NR base station according to an embodiment of the present invention.

[0147] As shown in the figure, the base station may include a transceiver 600, a backhaul communication unit 630, a storage unit 640, and a controller 650. The transceiver 600 may include an RF processing unit 610 and a baseband processing unit 620. The transceiver 600 may be referred to as a communication unit. The controller 650 may include a dual-connectivity processing unit 652.

[0148] The RF processing unit 610 included in transceiver 600 can perform functions for transmitting / receiving signals over a radio channel, such as signal band conversion and amplification. The RF processing unit 610 can up-convert a baseband signal provided from baseband processing unit 620 to an RF band signal, then transmit that signal through an antenna, and down-convert an RF band signal received through the antenna back to a baseband signal. For example, the RF processing unit 610 may include transmit filters, receive filters, amplifiers, mixers, oscillators, DACs, ADCs, etc. Only one antenna is shown in the figures, but the first access node may include multiple antennas. Furthermore, the RF processing unit 610 may include multiple RF chains. Additionally, the RF processing unit 610 can perform beamforming. For beamforming, the RF processing unit 610 can adjust the phase and amplitude of each signal transmitted and received through multiple antennas or antenna elements. The RF processing unit 610 can perform downlink MIMO operation by transmitting one or more layers.

[0149] The baseband processing unit 620 included in transceiver 600 performs conversion functions between baseband signals and bitstreams according to the physical layer specifications of the first radio access technology. For example, when transmitting data, the baseband processing unit 620 can generate complex symbols by encoding and modulating the transmitted bitstream. Furthermore, when receiving data, the baseband processing unit 620 can recover the received bitstream by demodulating and decoding the baseband signal provided from the RF processing unit 610. For example, when following an OFDM scheme, when transmitting data, the baseband processing unit 620 can generate complex symbols by encoding and modulating the transmitted bitstream, map the complex symbols to subcarriers, and then configure the OFDM symbols through IFFT operations and CP insertion. Furthermore, when receiving data, the baseband processing unit 620 can divide the baseband signal provided from the RF processing unit 610 based on OFDM symbols, recover the signals mapped to subcarriers through FFT operations, and then recover the received bitstream through demodulation and decoding. The baseband processing unit 620 and the RF processing unit 610 can transmit / receive signals as described above.

[0150] The backhaul communication unit 630 can provide an interface for performing communication with other nodes in the network. The backhaul communication unit 630 can convert bit streams sent from the primary base station to another node (e.g., a secondary base station, core network, etc.) into physical signals, and convert physical signals received from another node into bit streams.

[0151] Storage unit 640 can store data such as basic programs, application programs, and configuration information for the operation of the main base station. Specifically, storage unit 640 can store information about bearers assigned to connected terminals, measurement results reported from connected terminals, etc. Furthermore, storage unit 640 can store information used as a criterion for determining whether to provide or suspend dual connectivity to terminals. Additionally, storage unit 640 can provide the stored data upon request from controller 650.

[0152] The controller 650 can control the overall operation of the base station. For example, the controller 650 can transmit / receive signals via the baseband processing unit 620 and the RF processing unit 610 or via the backhaul communication unit 630. Furthermore, the controller 650 writes data to / reads data from the storage unit 640. For this purpose, the controller 650 may include at least one processor.

[0153] In the following text, the terms used in this disclosure are defined as follows.

[0154] -CHO: Condition toggle.

[0155] -CPAC: Conditional PSCell addition and modification.

[0156] -CHO+CPAC: Configure and execute conditional switching and conditional PSCell addition and modification operations simultaneously in the terminal.

[0157] - Target Cell Configuration: In the case of CHO+CPAC operation, the target cell configuration can refer to an RRCReconfiguration message that includes MCG configuration and SCG configuration. The MCG configuration includes a target PCell configuration, and the SCG configuration includes a target PSCell configuration. This message can include the radio bearer configuration, measurement configuration, MCG (primary cell group) configuration, and SCG (secondary cell group) configuration that can be included in a typical RRCReconfiguration message.

[0158] - Conditions: Unless otherwise stated, this refers to execution conditions, and a condition may include multiple measIds, each consisting of a measurement object and a reporting configuration configured in the measurement configuration.

[0159] CHO configuration refers to the configuration required for conditional switching, and CHO+CPAC configuration refers to the simultaneous configuration of conditional switching and conditional PSCell addition and modification operations on the terminal.

[0160] In this disclosure, CHO may include the CHO discussed in 3GPP Release 16, and CHO+CPAC may include the CHO+CPAC discussed in 3GPP Release 18, but this disclosure is not limited thereto.

[0161] When the network configures a CHO+CPAC for a terminal, the terminal can perform a move to a specific target PCell and a specific target PSCell linked to that condition when certain association conditions are met. In this case, when conditions corresponding to the target PCell and the target PSCell are given for each CHO+CPAC, the terminal determines whether the conditions are met, and when the conditions corresponding to the target PCell and the target PSCell are met, the terminal can execute a CHO+CPAC configuration.

[0162] The target PCell configuration and the target PSCell configuration can depend on each other. In other words, a target PCell configuration can vary depending on the target PSCell configuration. Furthermore, the CPAC configuration can depend on the CHO configuration.

[0163] In the following text, when both the CHO configuration and the CHO+CPAC configuration are provided to the terminal and the terminal fails during the process at the MCG, and when the cell selected during the RRC rebuild operation corresponds to one of the PCells in the CHO+CPAC configuration, it is described whether the CHO+CPAC configuration is used together with the CHO configuration. In other words, when both the CHO configuration and the CHO+CPAC configuration are provided to the terminal and the terminal fails during the process at the MCG, it is described whether the CHO+CPAC configuration is used together with the CHO configuration.

[0164] Figure 7 Configuration information according to an embodiment of this disclosure is shown.

[0165] More specifically, Figure 7 This is a view that shows detailed information when CHO configuration and CHO+CPAC configuration are given to the terminal.

[0166] refer to Figure 7 In a CHO configuration, the target PCell is unique across all configurations. For example, PCells 1, 2, and 3 each currently have a CHO configuration and are associated with a specific ID. Within a CHO configuration, there may be configurations that include a specific PSCell, such as ID 2.

[0167] like Figure 7As shown, when configuring CHO+CPAC in the network, each CHO+CPAC configuration always includes configuration information for a specific target PCell and a specific target PSCell. In this case, CHO+CPAC configurations can overlap relative to PCells and can also overlap relative to PSCells, but if both PCells and PSCells are the same, only one CHO+CPAC can exist.

[0168] like Figure 7 As shown, assuming that the CHO configuration and CHO+CPAC configuration are given to the terminal, if the cell selected by the terminal during the RRE operation is PCell 1, then the terminal should select a configuration from ID 1 in the CHO configuration and select a configuration from IDs 4, 5, 6, and 7 in the CHO+CPAC configuration.

[0169] When cell 1 is configured as a candidate cell for PCell in the CHO configuration, and cell 2 is configured as a candidate cell for PCell and cell 3 as a candidate cell for PSCell in the CHO+CPAC configuration, if the terminal experiences a failure in the MCG and the cell selection result is cell 2, the CHO+CPAC configuration can be used even if only the RRC reconstruction process can be performed and the failure recovery mechanism cannot be used with the existing CHO candidate cells. In this case, it has the effect of shortening the connection interruption time.

[0170] In this disclosure, the following method is proposed regarding whether to use the CHO+CPAC configuration for the case of MCG failure as described above.

[0171] Method 1: Using CHO+CPAC configuration even if MCG fails.

[0172] Method 2: A method to avoid using CHO+CPAC configuration in case MCG fails.

[0173] The details of each method are described below.

[0174] Method 1: Using CHO+CPAC configuration even if MCG fails.

[0175] In this case, the conditions under which the terminal can use CHO+CPAC configuration to fail are as follows.

[0176] - Radio link failure (RLF) on the MCG

[0177] - Reconfiguration failed

[0178] -reconfigurationWithSync failed

[0179] - Encryption failed

[0180] - Security Failure

[0181] - Integrity protection failed

[0182] In addition, the following conditions may be applied. The part indicated here refers to the part based on the 3GPP RAN RRC specification (TS38.331-v17.2.0).

[0183] 1> According to 5.3.10, when a radio link failure of the MCG is detected and t316 is not configured; or

[0184] 1> According to 5.3.10, when a radio link failure of the MCG is detected while SCG transmission is suspended; or

[0185] 1> According to 5.3.10, when a radio link failure of the MCG is detected while a PSCell change or PSCell addition is in progress; or

[0186] 1> According to 5.3.10, when the radio link failure of the MCG is detected at the same time as the SCG is deactivated; or

[0187] 1> In accordance with clause 5.3.5.8.3, during reconfiguration in the event of MCG synchronization failure; or

[0188] 1> In accordance with Clause 5.4.3.5, in the event of a mobility failure from an NR; or

[0189] 1> When an integrity check failure indication comes from a lower level regarding SRB1 or SRB2, unless an integrity check failure is detected on an RRCReestablishment message; or

[0190] 1> According to clause 5.3.5.8.2, when RRC connection reconfiguration fails; or

[0191] 1> When a radio link failure of the SCG is detected during an MCG transmission suspension, pursuant to Clause 5.3.10.3 of NR-DC or Clause 5.3.11.3 of TS 36.331

[10] of NE-DC; or

[0192] 1> During reconfiguration in the event of SCG synchronization failure while suspending MCG transmission according to clause 5.3.5.8.3; or

[0193] 1> When the SCG change fails while the MCG transmission is suspended pursuant to Clause 5.3.5.7a of TS 36.331

[10] ; or

[0194] 1> When SCG configuration fails while MCG transmission is suspended pursuant to Clause 5.3.5.8.2 of NR-DC or Clause 5.3.5.5 of TS 36.331

[10] of NE-DC; or

[0195] 1> When the MCG is paused, upon receiving an integrity check failure indication regarding SRB3 from the lower layer of the SCG; or

[0196] 1> According to clause 5.7.3b.5, upon expiry of T316; or

[0197] 1> According to clause 5.8.9.3, when a sidelink radio link failure is detected by an L2 U2N remote UE in RRC_CONNECTED state; or

[0198] 1> According to clause 5.8.9.10, when a NotificationMessageSidelink including indicationType is received by an L2 U2N remote UE in RRC_CONNECTED state; or

[0199] 1> When the PC5 unicast link is released by the upper layer at the L2 U2N remote UE in RRC_CONNECTED state.

[0200] In the event of a failure, the terminal can perform cell selection. In this case, cell selection refers to the existing cell selection operation. (In other words, this does not consider CHO and CHO+CPAC configuration-related operations.)

[0201] After selecting the cell on the terminal, there are two options for using CHO+CPAC configuration in Method 1.

[0202] Option 1. Consider only the case of candidate PCells with CHO+CPAC configuration.

[0203] Option 2. Consider both the CHO candidate PCell and the CHO+CPAC candidate PCell configurations.

[0204] Options 1 and 2 are described in detail below.

[0205] Option 1. Consider only the case of candidate PCells with CHO+CPAC configuration.

[0206] For option 1, there are three possible scenarios where the terminal can differentiate between them.

[0207] Scenario 1) The CHO+CPAC configuration is included in a separate field / IE and passed to the terminal:

[0208] This is the case where the selected cell is the same as the target cell in the reconfigurationWithSync field within the masterCellGroup field of condRRCReconfig, i.e., the target cell configuration included in the CHO+CPAC specific condition reconfiguration variable of MCG.

[0209] Case 2) The CHO+CPAC configuration is configured as a separate set of condReconfig IDs and passed to the terminal:

[0210] This is the case where the selected cell is included in the conditional reconfiguration variable of the MCG, is a conditional reconfiguration with an ID within the range of the id set, and is the same as the target cell (i.e., the target cell configuration) included in the reconfigurationWithSync field of the masterCellGroup field of the linked condRRCReconfig.

[0211] Case 3) The CHO+CPAC configuration is included in the same fields as the CHO configuration, passed to the terminal, and stored in the same variables:

[0212] This is the case where the selected cell is the same as the target cell in the reconfigurationWithSync field of the masterCellGroup field in condRRCReconfig (i.e., target cell configuration) included in the conditional reconfiguration variable of MCG, and condRRCReconfig is linked to conditions that include both the conditional information of the target PCell and the conditional information of the target PSCell.

[0213] In this scenario, for the selected target PCell, the terminal can apply the target cell configuration when only a target cell configuration exists. However, for the selected target PCell, there may be target cell configurations linked to multiple different target PSCells, and in this case, an additional operation should be performed regarding "which target PScell ​​should be selected from among the multiple CPAC target PSCells linked to a CHO target PSCell for its target cell configuration." This will be described below.

[0214] Option 2. Consider both CHO candidate PCells and CHO+CPAC candidate PCells together: The following additional options are possible.

[0215] Additional option 1. Select the implementation to leave to the terminal.

[0216] Specifically, when the cell selected by the terminal in the RRE operation is the same as the target PCell configured in CHO and / or the same as the target PCell configured in CHO+CPAC, the terminal determines whether to select the target cell configuration configured in CHO or the target cell configuration configured in CHO+CPAC.

[0217] Additional option 2. The PCell configured in CHO takes precedence over the target cell configuration in CHO+CPAC.

[0218] When the cell selected by the terminal during the RRE operation is the same as the target PCell configured in the CHO configuration and also the same as the target PCell configured in the CHO+CPAC configuration, the terminal can apply the CHO configuration. Otherwise, the terminal can apply the same CHO or CHO+CPAC configuration as the selected cell.

[0219] The following are examples of operations. This can include examples from the specification.

[0220] 1. If the selected cell is one that is included in the masterCellGroup field of MCGVarConditionalReconfig, and its execution conditions consist only of execution conditions related to Pcell / CHO.

[0221] - Apply the condRRCReconfig;

[0222] 2. Otherwise, if the selected cell is one that is included in the masterCellGroup field of MCGVarConditionalReconfig and its execution conditions consist of execution conditions related to Pcell / CHO and Pscell / CPAC.

[0223] - If multiple configurations exist, select one based on subsequent page conditions:

[0224] Additional option 3. CHO+CPAC configuration takes precedence over CHO configuration.

[0225] A. When the cell selected by the terminal during RRE operation is the same as the target PCell in the CHO configuration and the same as the target PCell in the CHO+CPAC configuration, the terminal can choose the CHO+CPAC configuration. Otherwise, the terminal can apply the same CHO or CHO+CPAC configuration as the selected cell. When the CHO+CPAC configuration is selected, different configurations can be applied for each target PSCell. This situation follows the procedure below regarding which target cell configuration should be selected among multiple CPAC target PSCells linked to a CHO target PSCell.

[0226] B. The following are examples of operations. This can include examples from the specification.

[0227] 1. If the selected cell is one that `reconfigurationWithSync` is included in the `masterCellGroup` field of `MCGVarConditionalReconfig`, and its execution conditions consist of execution conditions related to `Pcell / CHO` and `Pscell / CPAC`; and

[0228] A. If multiple configurations exist, select one more based on subsequent page conditions: and

[0229] B. Apply the condRRCReconfig;

[0230] 2. Otherwise, if the selected cell is one that is included in the masterCellGroup field of MCGVarConditionalReconfig and its execution conditions consist only of execution conditions related to Pcell / CHO.

[0231] A. Apply the condRRCReconfig;

[0232] When applying the target cell configuration of CHO+CPAC as described above, the operation of "selecting which target PScell ​​to link to among multiple CPAC target PSCells linked to a CHO target PSCell" can follow several additional options. Furthermore, here, selecting the target PSCell has the same meaning as selecting the CHO+CPAC target cell configuration that includes the target PSCell.

[0233] Additional option 3-1. The terminal may follow an implementation method for selecting multiple PSCells.

[0234] Additional option 3-2. The network can explicitly indicate the target cell configuration for CHO+CPAC.

[0235] In other words, when a terminal performs cell selection while performing RRE operation, if there are multiple configurations where the selected cell matches the CHO target PCell in the CHO+CPAC configuration, the terminal can be explicitly instructed on the configuration to be applied. In this case, the information indicated by the network can tell the terminal the applicable target condition reconfiguration ID or the PCI (Physical Cell ID) and / or ARFCN (Absolute Radio Channel) information of a specific PSCell among multiple target PSCells.

[0236] Additional Option 3-3. The terminal can select a CHO+CPAC configuration from multiple PSCells that meet the associated CPAC condition information. In this case, if multiple PSCells meet the CPAC condition information, the terminal can select any PSCell or the signal with the strongest received signal strength. Alternatively, the terminal can select the lowest condition among the CHO+CPAC configurations of the PSCells that meet the conditions to reconfigure the ID.

[0237] Additional options 3-4. If a currently configured PSCell exists, the terminal can select the CHO+CPAC configuration where the PSCell is set as the target PSCell. In this case, the PSCell should not be disabled and sending / receiving should not be paused.

[0238] Additional options 3-5: The terminal can select the PSCell with the strongest received signal strength.

[0239] Additional options 3-6. The terminal can select a specific configuration from multiple CHO+CPAC configurations and apply the configuration only for the PCell in that configuration. In this case, the current PSCell configuration can remain unchanged, or an MRDC (Multiple RAT (Radio Access Technology) Dual Connection) release operation can be performed.

[0240] Additional options 3-7. Operations can be combined by assigning priority to each condition. For example, among multiple PSCells, if there is a PSCell currently configured with a DC and also meets the CPAC condition of the PSCell, then the CHO+CPAC configuration of the PSCell can be selected. Alternatively, if the terminal is not currently configured with a DC, then additional option 3-6 can be applied.

[0241] When the CHO+CPAC configuration selection is complete, the terminal can apply the configured condRRCReconfiguration, i.e., the RRCReconfiguration message.

[0242] After performing the operation and the terminal applying the message, the terminal can prepare an RRCReconfigurationComplete message for the selected CHO+CPAC configuration and send this message to the gNB (T-MN) of the target PCell of the selected CHO+CPAC. In this case, the RRCReconfigurationComplete message may include at least one of the following: the selected CHO+CPAC configuration information, the conditional reconfiguration ID of the selected CHO+CPAC configuration, the PCI and ARFCN information of the target PCell of the CHO+CPAC configuration, and / or the PCI and ARFCN information of the target PSCell. When the RRCReconfigurationComplete message containing the information is sent to the target MN during the CPAC operation, the T-MN can identify which cell / which SN node is the new T-SN and know that the reconfiguration is complete.

[0243] Figure 8 The operational sequence of the terminal and network according to embodiments of this disclosure is shown.

[0244] The following section describes the operation of the signaling system related to capabilities.

[0245] refer to Figure 8 When UE 800 initially connects to the network or after establishing an RRC connection to S-MN (Source-Master Node) 803, UE 800 may send a UE capability indication (810) to S-MN 803 indicating support for RRC Reconstruction (RRE) with CHO+CPAC configuration.

[0246] In other words, UE 800 may include a 1-bit indicator indicating that the CHO+CPAC configuration can be used as the target cell configuration after cell selection in RRE, and send it to the base station (S-MN) in the UECapabilityInformation message or UL RRC message.

[0247] In other words, when the cell selected after the cell selection during the RRC rebuild operation is included in the target cell of the CHO+CPAC configuration, especially when it is the same as the target PCell, the UE 800 can include and transmit an indicator indicating support for the operation of applying the CHO+CPAC configuration through the UE capability information or the corresponding UL RRC message.

[0248] S-MN 803 can configure UE 800 to apply features corresponding to the UE capability information sent by UE 800 to S-MN 803 in step 810 (820).

[0249] In other words, the network receiving the indicator can include and pass the indicator to the UE 800 via a DL RRC message or an RRCReconfiguration message. This indicator indicates whether to perform the traditional attemptCondReconfig on the cell selected during RRE, apply only the CHO+CPAC configuration, or use the existing CHO configuration and CHO+CPAC configuration.

[0250] In other words, the network receiving the indicator can then include the indicator for the following in a separate DL RRC message or RRCReconfiguration message and pass it to the terminal.

[0251] - Existing traditional attemptCondReconfig directive

[0252] - Only use the CHO+CPAC configuration as an indicator for candidate configurations to be used in RRE cell selection.

[0253] - Consider the indicators for both the CHO+CPAC and CHO configurations used for candidate configurations to be used in RRE cell selection (i.e., consider the configuration in the masterCellGroup field of condRRCReconfig where reconfigurationWithSync is included in the conditional reconfiguration).

[0254] exist Figure 8 For example, suppose that an indicator in the indicator list that only uses CHO+CPAC configuration is passed for configuration.

[0255] When passing CHO configuration or CHO+CPAC configuration information, the indicator can be passed together in the RRCReconfiguration message.

[0256] After the CHO and / or CHO+CPAC configuration is passed, UE 800 and S-MN 803 can perform CHO and / or CHO+CPAC configuration (830).

[0257] Afterward, UE 800 performs measurement and condition assessment operations, and when PCell fails during this process (the detailed conditions for failure are described above), UE 800 can perform RRC reconstruction operations and thus can perform cell selection (840).

[0258] If the selected cell is the same as the CHO target PCell in the CHO+CPAC configuration, the UE 800 can select and apply the CHO+CPAC configuration (or the CHO+CPAC configuration with a specific target PSCell) (850).

[0259] The configuration enables the execution of mobility operations on the target PCell and the target PSCell.

[0260] After the application is executed, UE 800 can perform random access with T-MN (target primary node) 807 (860). Additionally, UE 800 can perform random access with T-SN (target secondary node) 809 (870). UE 800 can send an RRCReconfigurationComplete message (880) to the target PCell in the configuration.

[0261] During this transmission, UE 800 can send RACH (Random Access Channel) preambles to PCell (or T-MN 807) and PSCell (or T-SN (Target Secondary Node) 809) and receive RAR (Random Access Response) from PCell. The RRCReconfigurationComplete message may include information about the CHO+CPAC configuration selected for the RRE procedure. The RRCReconfigurationComplete message may also include the selected condReconfig ID.

[0262] Here, if the CHO configuration is selected based on the above options, the selected condReconfigID can be the PCI and / or ARFCN of a specific target PCell in the CHO configuration, or a conditional reconfiguration ID referencing the target PCell configuration. Alternatively, if the CHO+CPAC configuration is selected, the selected condReconfig ID can be a conditional reconfiguration ID corresponding to a specific CHO+CPAC configuration, and the CHO+CPAC configuration can include the PCI and / or ARFCN of the configured target PCell and the PCI and / or ARFCN information of the configured target PSCell. T-MN 807 can know from the included configuration information that UE 800 has moved from S-MN 803, and what the current PSCell and T-SN 809 are. Therefore, T-MN 807 can notify T-SN 809 that the application of the CHO+CPAC configuration of UE 800 is complete (890). Subsequently, the UE800 can operate in a dual-connection configuration with the PCell of the new T-MN 807 and the PSCell of the T-SN 809.

[0263] Method 2: A method to avoid using CHO+CPAC configuration in case MCG fails.

[0264] In this scenario, if MCG fails, the terminal does not treat the CHO+CPAC configuration as the configuration applied to the selected cell during RRE. In other words, the terminal may only consider traditional CHO candidate cells.

[0265] In this case, you can use only the CHO configuration, and the process is as follows.

[0266] 1> If cell selection is triggered by detecting a radio link failure of the MCG, a reconfiguration of the MCG synchronization failure, or mobility from an NR failure, and

[0267] 1> If attemptCondReconfig is configured; and

[0268] 1> If the selected cell is not configured with CondEventT1, or if the selected cell is configured with CondEventT1 but the leave condition has not yet been met; and

[0269] 1> If the selected cell is one of the candidate cells whose reconfigurationWithSync is included in the masterCellGroup in MCGVarConditionalReconfig:

[0270] 2> If the UE supports RLF reporting for conditional handover, set the choCellId in the VarRLF report to the global cell identifier (if available), otherwise set it to the physical cell identifier and carrier frequency of the selected cell;

[0271] 2> Apply the stored condRRCReconfig associated with the selected cell and perform the actions specified in 5.3.5.3;

[0272] In other words, for Method 2 to be applied, the selected cell should correspond to the configuration information stored in the variables used for conditional reconfiguration of the MCG, and should be the target candidate cell included in the `reconfigurationWithSync` field of its `matterCellGroup` field. However, CHO+CPAC configuration information can be stored together with CHO configuration information in the variables used for conditional reconfiguration of the MCG. In that case, it is necessary to distinguish between the configuration for CHO and the CHO+CPAC configuration, and the CHO+CPAC configuration should be excluded.

[0273] Therefore, the following additional constraints are necessary. In other words, when the selected cell is configuration information stored in variables used for conditional reconfiguration of the MCG and is a target candidate cell included in the reconfigurationWithSync field of its materCellGroup field, at least one of the following constraints is necessary:

[0274] - The stored configuration information is not CHO+CPAC configuration information;

[0275] - The stored configuration information is not the configuration information linked to CHO condition information and CPAC condition information, i.e., PCell target condition information and PSCell target condition information.

[0276] Figure 9 The operation of a terminal according to an embodiment of the present invention is illustrated.

[0277] In an embodiment, when the first target network node of the Radio Resource Control (RRC) reconstruction process is selected, the terminal may send a first indicator (910) to the source network node indicating support for the simultaneous configuration of conditional handover and conditional PSCell (primary and secondary cell) addition and change (conditional handover + conditional pscell addition and change, CHO + CPAC configuration).

[0278] In an embodiment, the terminal may receive a second indicator (920) related to the use of the CHO+CPAC configuration from the source network node.

[0279] In an embodiment, the terminal may, in response to the detection of a failure in the primary cell group (MCG), select the first target network node (930) for the RRC reconstruction process based on a second indicator.

[0280] In an embodiment, the terminal may send an RRCReconfigurationComplete message to a first target network node. The RRCReconfigurationComplete message may include at least one of the following: the selected CHO+CPAC configuration indicated by a second indicator; the conditional reconfiguration identifier (ID) of the selected CHO+CPAC configuration; and information regarding the target primary cell (PCell) and target primary-secondary cell (PSCell) indicated by the selected CHO+CPAC configuration. In an embodiment, the second indicator may include one of the following: a third indicator indicating that the CHO+CPAC configuration is not considered; a fourth indicator indicating that the CHO+CPAC configuration is considered; and a fifth indicator indicating that both the CHO+CPAC configuration and the conditional handover (CHO) configuration are considered.

[0281] In this embodiment, the terminal can select a second target network node during the RRC reconstruction process. Furthermore, when the second indicator includes a fourth indicator and the second target network node is the same as the candidate target network node indicated by the CHO+CPAC configuration, the terminal can select the candidate target network node as the first target network node.

[0282] In an embodiment, when the second indicator includes a fourth indicator indicating that the CHO+CPAC configuration is being considered, information about the candidate target network node indicated by the CHO+CPAC configuration may be included in the reconfigurationWithSync field, included in the condReconfig ID set, or included in the same field as the CHO configuration and sent to the terminal.

[0283] In an embodiment, the first target network node in the RRC reconstruction process may include a target primary network node and a target secondary network node.

[0284] The methods described in the embodiments of this disclosure or in the claims can be implemented in hardware, software, or a combination of hardware and software.

[0285] When implemented in software, a computer-readable storage medium may be provided to store one or more programs (software modules). The one or more programs stored in the computer-readable storage medium are configured to be executed by one or more processors in an electronic device. The one or more programs include instructions that enable the electronic device to perform methods according to embodiments described in the specification or claims of this disclosure.

[0286] The program (software module or software) can be stored in random access memory, including non-volatile memory such as flash memory, read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), disk storage devices, optical disc ROM, digital versatile optical disc (DVD), or other types of optical storage devices or magnetic tape cartridges. Alternatively, the program can be stored in a memory consisting of all or some of these components. Each component memory may include multiple memories.

[0287] The program can be stored in an attachable storage device accessible via a communication network, such as the Internet, intranet, local area network (LAN), wide area network (WLAN), or storage area network (SAN), or a combination thereof. The storage device can be connected to a device executing embodiments of this disclosure via an external port. A separate storage device on the communication network can be connected to a device executing embodiments of this disclosure.

[0288] In the specific embodiments described above, depending on the proposed specific embodiments, the components included in this disclosure are represented in a singular or plural form. However, the singular or plural form is chosen to suit the context suggested for ease of description, and this disclosure is not limited to singular or plural components. As used herein, the singular forms “a,” “an,” and “the” are intended to also include the plural forms, unless the context clearly indicates otherwise.

[0289] Although specific embodiments of the invention have been described above, various modifications can be made thereto without departing from the scope of the invention. Therefore, the scope of this disclosure should not be limited to the above embodiments, but should be defined by the appended claims and their equivalents.

Claims

1. A method for a terminal in a wireless communication system, the method comprising: Receive configuration information related to conditional handover from the source network node; In response to the detection of a failure in the primary cell group (MCG), the first cell is selected; as well as Based on the candidate cell information included in the configuration information related to conditional handover, the selected first cell is determined as the target cell for the Radio Resource Control (RRC) reconstruction process. Among them, for candidate cells with configuration information related to condition handover corresponding to the first cell, target condition information for primary and secondary cells (PSCell) is not configured.

2. The method according to claim 1, further comprising: Send a first indicator to the source network node, the first indicator indicating that when the target cell of the RRC reconstruction process is selected, it supports the simultaneous configuration of conditional handover and conditional PSCell addition and change (conditional handover + conditional PSCell addition and change, CHO + CPAC configuration).

3. The method according to claim 2, wherein, The configuration information related to conditional handover includes at least one of the following: CHO+CPAC configuration, conditional reconfiguration identifier (ID) of the selected CHO+CPAC configuration, and information about the target primary cell (PCell) and target primary secondary cell (PSCell) indicated by the selected CHO+CPAC configuration.

4. The method according to claim 1, wherein, The target condition information for PSCell is included in the condExecutionCondPSCell field of the configuration information related to condition switching.

5. A method in a network node of a wireless communication system, comprising: The terminal is sent configuration information related to conditional handover, including candidate cell information to determine the target cell for the Radio Resource Control (RRC) reconstruction process in the event of a failure in the Primary Cell Group (MCG). Specifically, for candidate cells with configuration information related to conditional handover that correspond to the determined target cell, primary and secondary cell (PSCell) target condition information is not configured.

6. The method according to claim 5, further comprising: Receive a first indicator from the terminal. The first indicator indicates that when the target cell of the RRC reconstruction process is selected, it supports the simultaneous configuration of conditional handover and conditional PSCell addition and change (conditional handover + conditional PSCell addition and change, CHO + CPAC configuration).

7. The method according to claim 6, wherein, The configuration information related to conditional handover includes at least one of the following: CHO+CPAC configuration, conditional reconfiguration identifier (ID) of the selected CHO+CPAC configuration, and information about the target primary cell (PCell) and target primary secondary cell (PSCell) indicated by the selected CHO+CPAC configuration.

8. The method according to claim 5, wherein, The target condition information for PSCell is included in the condExecutionCondPSCell field of the configuration information related to condition switching.

9. A terminal in a wireless communication system, the terminal comprising: transceiver; and At least one processor, wherein the at least one processor is configured to: Receive configuration information related to conditional handover from the source network node; In response to the detection of a failure in the primary cell group (MCG), the first cell is selected; and Based on the candidate cell information included in the configuration information related to conditional handover, the selected first cell is determined as the target cell for the Radio Resource Control (RRC) reconstruction process. Among them, for candidate cells with configuration information related to condition handover corresponding to the first cell, target condition information for primary and secondary cells (PSCell) is not configured.

10. The terminal according to claim 9, further comprising: Send a first indicator to the source network node, the first indicator indicating that when the target cell of the RRC reconstruction process is selected, it supports the simultaneous configuration of conditional handover and conditional PSCell addition and change (conditional handover + conditional PSCell addition and change, CHO + CPAC configuration).

11. The terminal according to claim 10, wherein, The configuration information related to conditional handover includes at least one of the following: CHO+CPAC configuration, conditional reconfiguration identifier (ID) of the selected CHO+CPAC configuration, and information about the target primary cell (PCell) and target primary secondary cell (PSCell) indicated by the selected CHO+CPAC configuration.

12. The terminal according to claim 9, wherein, The target condition information for PSCell is included in the condExecutionCondPSCell field of the configuration information related to condition switching.

13. A network node in a wireless communication system, the network node comprising: transceiver; and At least one processor, wherein the at least one processor is configured to: Send configuration information related to condition switching to the terminal. This includes candidate cell information in the configuration information related to conditional handover, used to determine the target cell for the Radio Resource Control (RRC) reconstruction process in the event of a failure in the Primary Cell Group (MCG), and Specifically, for candidate cells with configuration information related to conditional handover that correspond to the determined target cell, primary and secondary cell (PSCell) target condition information is not configured.

14. The network node according to claim 13, wherein, The network node is also configured to receive a first indicator from the terminal, the first indicator indicating that when the target cell of the RRC reconstruction process is selected, simultaneous configuration of conditional handover and conditional PSCell addition and modification is supported (conditional handover + conditional PSCell addition and modification, CHO + CPAC configuration), and The configuration information related to conditional handover includes at least one of the following: CHO+CPAC configuration, conditional reconfiguration identifier (ID) of the selected CHO+CPAC configuration, and information about the target primary cell (PCell) and target primary-secondary cell (PSCell) indicated by the selected CHO+CPAC configuration.

15. The network node according to claim 13, wherein, The target condition information for PSCell is included in the condExecutionCondPSCell field of the configuration information related to condition switching.

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