Method and apparatus for handling path failure of chain in wireless communication system

Abstract

The present disclosure provides a method performed by a first base station in which a primary cell group (MCG) is configured in a wireless communication system, and the first base station. The method includes: identifying a secondary cell group (SCG) failure associated with the SCG; transmitting a first radio resource control (RRC) connection reconfiguration message including configuration information for measurement to a user equipment (UE) associated with the SCG failure, and receiving a measurement report based on the configuration information from the UE; transmitting a first secondary node modification request message including information on a candidate cell list and a measurement result based on the measurement report to a second base station in which the SCG is configured; receiving, from the second base station, a message including information on a target cell associated with SCG recovery of the UE; and transmitting a second RRC connection reconfiguration message including information on the target cell to the UE.

Description

[0001] This application is a divisional application of the invention patent application filed on January 12, 2021, with application number 202180009409.8 and invention title "Method and apparatus for handling link faults in a wireless communication system". Technical Field

[0002] This disclosure generally relates to wireless communication systems, and more specifically, to apparatus and methods for handling link failures in wireless communication systems. Background Technology

[0003] To meet the growing demand for wireless data traffic following the commercialization of 4G communication systems, efforts are underway to develop improved 5G communication systems, or pre-5G communication systems. For this reason, 5G communication systems or pre-5G communication systems are referred to as super-4G network communication systems or post-Long Term Evolution (LTE) systems.

[0004] To achieve high data transmission rates, 5G communication systems are considered to be implemented in millimeter-wave bands (e.g., the 60 GHz band). To reduce propagation path loss and increase propagation distance in the millimeter-wave band, technologies such as beamforming, massive MIMO, full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and massive MIMO are being discussed in 5G communication systems.

[0005] In addition, to improve the network of the system, technologies such as evolved small cells, advanced small cells, cloud radio access networks (RAN), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, mobile networks, cooperative communication, multi-point cooperation (CoMP), and receive interference cancellation are being developed in 5G communication systems.

[0006] In addition, hybrid frequency shift keying and orthogonal amplitude modulation (FQAM) and sliding window superposition coding (SWSC) are being developed as advanced coding and modulation (ACM) technologies in 5G systems, as well as filter bank multicarrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) technologies.

[0007] Effective communication services can be provided in multiple-connection systems where base stations and terminals are coupled through independent radio access technologies. With the introduction of multiple-connection systems, a method is needed to handle link failures (e.g., radio link failures (RLFs)) when a link failure occurs in a cell group. Summary of the Invention

[0008] Technical issues

[0009] Based on the above discussion, this disclosure provides an apparatus and method for handling link failures when they occur in a wireless communication system.

[0010] Furthermore, this disclosure provides an apparatus and method for handling faults when receiving fault information about a cell group in a wireless communication system.

[0011] Furthermore, this disclosure provides an apparatus and method for managing link failures by processing the cells and bearers of a base station in an environment where multiple cell groups are configured in a wireless communication system.

[0012] Technical solution

[0013] According to various embodiments of this disclosure, a method for configuring a base station in a wireless communication system with a primary cell group (MCG) may include: detecting a fault in the primary cell (PScell) of an auxiliary cell group (SCG); based on the detection, sending inter-Radio Access Technology (RAT) measurement configuration information to a terminal; and sending information about a cell identified based on the measurement configuration information to the base station configured with the SCG.

[0014] According to various embodiments of this disclosure, a base station configured with a primary cell group (MCG) in a wireless communication system may include: at least one transceiver; and at least one processor. The at least one processor may be configured to: detect a fault in the primary cell (PScell) of an auxiliary cell group (SCG); based on the detection, send inter-Radio Access Technology (RAT) measurement configuration information to a terminal; and send information about a cell identified based on the measurement configuration information to the base station configured with the SCG.

[0015] According to various embodiments of this disclosure, a method for configuring a base station with an SCG in a wireless communication system may include: detecting a fault in a PScell; identifying a cell based on the detection; and performing a connection process with a terminal by sending information about the cell to a base station configured with an MCG.

[0016] According to various embodiments of this disclosure, a method performed by a first base station in a wireless communication system, wherein a primary cell group (MCG) is configured, may include: identifying an SCG fault associated with a secondary cell group (SCG); sending a first radio resource control (RRC) connection reconfiguration message, including configuration information for measurement, to a user equipment (UE) associated with the SCG fault; receiving a measurement report based on the configuration information from the UE; sending a first secondary node modification request message, including information about a candidate cell list and measurement results based on the measurement report, to a second base station in which the SCG is configured; receiving a message from the second base station including information about a target cell associated with SCG recovery of the UE; and sending a second RRC connection reconfiguration message to the UE including information about the target cell.

[0017] According to various embodiments of this disclosure, a first base station in a wireless communication system configured with a primary cell group (MCG) may include: a transceiver; a memory storing one or more computer programs; and one or more processors communicatively coupled to the transceiver and the memory, wherein the one or more programs include computer-executable instructions that, when executed individually or jointly by the one or more processors, cause the first base station to: identify an SCG fault associated with a secondary cell group (SCG); send a first radio resource control (RRC) connection reconfiguration message including configuration information for measurement to a user equipment (UE) associated with the SCG fault; receive a measurement report based on the configuration information from the UE; send a first secondary node modification request message including information about a candidate cell list and measurement results based on the measurement report to a second base station configured with the SCG; receive a message including information about a target cell associated with SCG recovery of the UE from the second base station; and send a second RRC connection reconfiguration message including information about the target cell to the UE.

[0018] Beneficial effects

[0019] The apparatuses and methods according to various embodiments of this disclosure can detect and control link failures, thereby providing effective communication performance when operating multiple-connectivity.

[0020] The advantages obtained by the present invention are not limited to those described above. Other advantages not mentioned herein can be clearly understood by those skilled in the art through the following description. Attached Figure Description

[0021] Figure 1 Wireless communication systems according to various embodiments of the present disclosure are shown;

[0022] Figure 2A Examples of cell groups in a wireless communication system according to various embodiments of the present disclosure are shown;

[0023] Figure 2B Another example of a cell group in a wireless communication system according to various embodiments of the present disclosure is shown;

[0024] Figure 3 Examples of signaling for controlling link failures in a master node (MN) in a wireless communication system according to various embodiments of the present disclosure are shown;

[0025] Figure 4 Examples of signaling for blacklisted cell management in a wireless communication system according to various embodiments of the present disclosure are shown;

[0026] Figure 5 Another example of signaling for blacklisted cell management in a wireless communication system according to various embodiments of the present disclosure is shown;

[0027] Figure 6 Examples of signaling for controlling link failures in a secondary node (SN) in a wireless communication system according to various embodiments of the present disclosure are shown;

[0028] Figure 7 The functional structure of a base station in a wireless communication system according to various embodiments of the present disclosure is illustrated; and

[0029] Figure 8 The functional structure of a terminal in a wireless communication system according to various embodiments of the present disclosure is shown. Detailed Implementation

[0030] The terminology used in this disclosure is for the purpose of describing particular embodiments only and is not intended to limit other embodiments. Singular expressions may include plural expressions unless there is a significant difference in context. All terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art as disclosed in this disclosure. It should also be understood that terms, such as those defined in common dictionaries, should be interpreted as having the meaning consistent with their meaning in the context of the relevant art and should not be interpreted in an idealized or overly formal sense, unless expressly defined herein. Optionally, the terms defined in this disclosure should not be construed as excluding embodiments of this disclosure.

[0031] For example, hardware-based methods are described in the various embodiments of this disclosure described below. However, since the various embodiments of this disclosure include techniques that use both hardware and software, software-based methods are not excluded from the embodiments of this disclosure.

[0032] In the following, this disclosure relates to an apparatus and method for managing link failures in a wireless communication system. Specifically, this disclosure describes a technique for controlling and handling link failures in a group of cells within a multi-connectivity environment of a wireless communication system.

[0033] For ease of illustration, examples are given below of terms related to multi-connectivity (e.g., dual connectivity (DC), multiple radio access technology (RAT) (MR)-DC, cell group, primary cell group (MCG), secondary cell group (SCG)), terms referring to signals (e.g., reference signal, system information, control signal, message, data), and terms referring to network entities (e.g., communication node, radio node, radio unit, network node, primary node (MN), secondary node (SN), transmit / receive point (TRP), digital unit (DU), radio unit (RU), massive MIMO unit (MMU)). Therefore, this disclosure is not limited to the terms described below, and other terms with the same technical meaning may also be used.

[0034] Furthermore, while this disclosure describes various embodiments using terminology used in some communication standards (e.g., the 3rd Generation Partnership Project (3GPP)), this is for illustrative purposes only. Various embodiments of this disclosure can be readily modified and applied to other communication systems.

[0035] In embodiments of this disclosure, at least one of various parameters can be used to measure whether conditions (e.g., measurement reporting conditions) are met and to measure the channel quality of the signal with respect to the measurement parameters. As channel quality, reference signal received power (RSRP), beam reference signal received power (BRSRP), reference signal received quality (RSRQ), received signal strength index (RSSI), signal-to-interference-plus-noise ratio (SINR), carrier-to-interference-plus-noise ratio (CINR), SNR, error vector magnitude (EVM), bit error rate (BER), block error rate (BLER), other terms with equivalent technical meaning, or other measures indicating channel quality can be used.

[0036] Figure 1 A wireless communication system 100 according to various embodiments of the present disclosure is shown. Figure 1 In this document, base stations 110-1, 110-2, ..., 110-n and terminal 120 are illustrated as nodes using radio channels in a wireless communication system. Base stations 110-1, 110-2, ..., 110-n can be coupled to terminal 120 via multiple connections (e.g., dual connections (DC)). For ease of description, in the following text, each of base stations 110-1, 110-2, ..., 110-n can be referred to as base station 110.

[0037] Base stations 110-1, 110-2, ..., 110-n are network infrastructure providing radio access to terminal 120. Base station 110 has a coverage area defined by the distance from which signals can be transmitted, representing a specific geographical region. The term "coverage" as used below can refer to the service coverage area within base station 110. Base station 110 may cover one cell or multiple cells. Here, multiple cells can be divided by supported frequencies and the area of ​​the coverage sectors.

[0038] In addition to the term "base station," base station 110 may be referred to as "access point (AP)," "eNodeB (eNB)," "fifth-generation (5G) node," "5G NodeB (NB)," "next-generation node B (gNB)," "radio point," "transmit / receive point (TRP)," "distributed unit (DU)," "radio unit (RU)," "remote radio headend (RRH)," or other terms with equivalent technical meanings. According to various embodiments, base station 110 may be coupled to at least one TRP. Base station 110 can transmit downlink signals to terminal 120 or receive uplink signals through at least one TRP.

[0039] As a device used by a user, terminal 120 communicates with base station 110 via a radio channel. Optionally, terminal 120 can be operated without user intervention. That is, as a device for performing machine-type communication (MTC), terminal 120 may not be carried by the user. In addition to the term "terminal," terminal 120 may also be referred to as "user equipment (UE)," "mobile station," "user station," "customer premises equipment (CPE)," "remote terminal," "wireless terminal," "electronic device," "vehicle-mounted terminal," "user equipment," or other terms with equivalent technical meanings.

[0040] Dual Connectivity (DC) is a multi-connectivity technology introduced from 3GPP standard release 12. In DC, a terminal is simultaneously coupled to two independent heterogeneous or homogeneous wireless communication cell groups, each with its own radio resource control entity. Frequency resources on component carriers of cells located in different frequency bands within each cell group are used for signal transmission / reception, improving frequency utilization efficiency for both the terminal and the base station. DC consists of a primary cell group whose control plane is directly coupled to the core network to manage the terminal's radio resource control state, and a secondary cell group associated with the primary cell group.

[0041] Carrier aggregation (CA) is a technology introduced in 3GPP version 10. In CA, terminals are coupled to homogeneous wireless communication cell groups with a common radio resource control entity. Frequency resources on component carriers of each cell located in different frequency bands are used for signal transmission / reception to improve the frequency utilization efficiency of terminals and base stations.

[0042] Due to their technological advantages in improving efficiency in utilizing the limited wireless communication resources of terminals and base stations, DC and CA technologies have received active research in academia. In particular, 5G mobile communication systems, which use a non-independent type of operation implemented in association with the 4G core network as their basic operating scheme, are being used as core technologies in supporting commercial services of 5G mobile communication systems.

[0043] In various embodiments of this disclosure, the cases where base stations 110-1, 110-2, ..., 110-n are coupled to terminal 120 via multiple connections are described. As described above, multiple connections refer to the communication technology by which terminal 210 is coupled to each base station 110-1, 110-2, ..., 110-n via an independent Radio Access Technology (RAT). For example, terminal 120 can be coupled to each of two base stations via Dual Connection (DC) as a type of multiple connection. For example, terminal 120 can be coupled to an eNB base station via Long Term Evolution (LTD) and to a gNB base station via New Radio (NR). Each base station can be referred to as a communication node. One or more cells provided in a base station can be referred to as a cell group. That is, a base station can support one or more cell groups. A base station providing a primary cell group (MCG) can provide a primary node (MN), and a base station providing a secondary cell group (SCG) can provide a secondary node (SN). In various embodiments, the relationship between base stations and cell groups can be defined differently. According to an embodiment, one base station can provide one cell group. Furthermore, according to another embodiment, one base station can provide one or more cell groups. Reference will be made below. Figure 2A and Figure 2B The specific relationships are described. Furthermore, according to an embodiment, each base station can perform carrier aggregation (CA). In this case, the terminal can perform CA on the base station through the cells of each cell group.

[0044] In various embodiments of this disclosure, multiple connections can be configured independently, or CA can be configured together with multiple connections. This disclosure provides a base station apparatus and method for performing operations to control the transmit power of a terminal in a distributed manner on a real-time basis and to control the transmit power of a terminal in a distributed manner on a non-real-time basis. The cell groups constituting multiple connections can be referred to as a first cell group, a second cell group, ..., the Mth cell group. In this disclosure, the first cell group can be replaced by a primary cell group constituting multiple connections, and the second cell group, ..., the Mth cell group can be replaced by a secondary cell group.

[0045] Figure 2A Examples of cell groups in a wireless communication system according to various embodiments of the present disclosure are shown. Figure 2A The wireless communication system illustrates a scenario where a base station manages all cell groups.

[0046] Reference Figure 2A Base station 110 can provide the terminal with multiple cell groups 211-1, 211-2, 211-3, ..., 211-M. Each of the multiple cell groups can include one or more cells. Although in Figure 2A A base station is described as managing all cell groups, but the invention is not limited thereto. In some embodiments, a separate network entity coupled to the base station may perform the link fault management process described below.

[0047] Figure 2B Another example of a cell group in a wireless communication system according to various embodiments of the present disclosure is shown. Figure 2B The wireless communication system illustrated illustrates a scenario where at least two base stations manage all cell groups. These at least two base stations can include base stations 110-1, 110-2, ..., 110-n.

[0048] Reference Figure 2B Base stations 110-1, 110-2, ..., 110-n can provide multiple cell groups 211-1, 211-2, 211-3, ..., 211-M to the terminal. In this case, the number of cell groups coupled to the base station can be configured differently for each base station. For example, the first base station 110-1 can provide three cell groups to the terminal (e.g., CG#1 261a, CG#2 261b, and CG#3 261c). The second base station 110-2 can provide three cell groups to the terminal (e.g., CG#4 262a, CG#5 262b, and CG#6 262c). The third base station 110-3 can provide two cell groups to the terminal (e.g., CG#7 263a and CG#8 263b). The Nth base station 110-n can provide one cell group to the terminal (e.g., CG#M 264). Each of the multiple cell groups can include one or more cells.

[0049] Despite Figure 2B The invention describes multiple base stations managing all cell groups, but is not limited thereto. In some embodiments, a separate network entity coupled to multiple base stations may perform the link fault management process described below.

[0050] In scenarios with multiple connections (e.g., dual connectivity (DC)) providing homogeneous or heterogeneous RATs, MCGs or SCGs may experience issues in the radio environment. When a radio link fails in the cell of an MCG or SCG (e.g., in the event of a radio link failure (RLF), optimized recovery may be required under the control of the base station.

[0051] When a fault occurs in an MCG or SCG, the node managing the cell group can receive fault information from the faulty node. In this case, the receiving node needs to manage recovery and other processing operations based on the fault information. That is, a method is needed to handle link faults in the MN of the MCG or the SN of the SCG. In the following, although the entity managing the MCG is described as the MN and the entity managing the SCG is described as the SN, embodiments implemented with a CU-DU structure (or including a DU-RU structure) with distributed deployment are not excluded, except that the base station is a single entity. According to embodiments, the MN managing the MCG may include a Central Unit (CU) - Control Plane (CP), a CU - User Plane (UP), and a Distributed Unit (DU). The SN managing the SCG may include a CU-CP, a CU-UP, and a DU. In the following, the multi-connection case where a terminal is simultaneously coupled to an MCG / SCG is described. The terminal may be coupled to one or more SCGs.

[0052] Based on the object experiencing the link failure and the entity handling the failure, the operation type can be divided into the following four categories.

[0053] (1) Methods for handling SCG faults by MN

[0054] (2) SN's method for handling SCG faults

[0055] (3) SN's method for handling MCG faults

[0056] (4) Methods for handling MCG faults in MN

[0057] SCG failure refers to the occurrence of RLF in the cell of an SCG. When an SCG failure occurs, the PCell of the SCG, i.e., the PSCell, is unsuitable for communication, which may require recovery through other nodes (e.g., MN). In the following, the operations are described based on scenarios (1) and (2), but unless otherwise stated, the same or similar processing methods can also be applied to scenarios (3) and (4). That is, the operations for handling failures in the other party's CG in scenarios (1) and (3) differ only in the network entity (NE) name, and the basic operation specifications are the same (when there are differences in some parts, they are specified separately). The operations for handling failures in their own CG in scenarios (2) and (4) differ only in the NE name, and the basic operation specifications are the same (when there are differences in some parts, they are specified separately).

[0058] Figure 3 Examples of signaling for controlling link failures in a master node (MN) in a wireless communication system according to various embodiments of this disclosure are shown. (Refer to...) Figure 3 This describes the operations between the MN, SN, and UE that are performed by the MN to handle SCG faults when an SCG fault occurs.

[0059] like Figure 3 As shown, multiple connections are implemented in the UE. The UE can be coupled to both the MN and the SN. The UE can be coupled to the Data Radio Bearer (DRB) active in both the MN and the SN. The UE can be coupled to the SN at the Radio Resource Control (RRC) / Packet Data Convergence Protocol (PDCP) level.

[0060] <1. SCG Fault Detection and Suspension>

[0061] The MN can detect SCG faults and notify the SN of the detected faults. In this case, the SN can suspend SCG transmission. The specific procedure is as follows.

[0062] In step S301, the MN can detect an SCG fault. The MN can receive information about the SCG fault (hereinafter referred to as SCG fault information) from the UE, or it can receive SCG fault information from the SN. The MN can detect an SCG fault by obtaining the SCG fault information. The MN can detect an RLF that has occurred in the SCG cell. The MN can receive SCG fault information from the other node or from the UE.

[0063] In step S303, the MN can send information about an SCG fault to the SN. This information can be sent in the form of a modification request message. The modification request message can include cell group configuration information (CG-ConfigInfo) or an X2 reason. The CG-ConfigInfo can include information about the cause of the SCG fault and measurement results (e.g., NR measurement results). The X2 reason can indicate that a UE connection cannot be found (e.g., radio connection with the UE is lost).

[0064] In step S305, the SN can suspend SCG transmission. The SN can identify faults in the SCG by receiving information about SCG faults from the MN. Optionally, the SN can autonomously detect faults in the SCG. Upon detecting an SCG fault, the SN suspends SCG transmission. Subsequently, in step S307, the SN can send a modification request response to the MN. This can be selectively sent to the MCG, including an NR RRC, to change the UL path.

[0065] <2. RAT Inter-measurement Configuration for SCG Recovery>

[0066] The MN can send measurement configurations to the UE to restore the SCG connection.

[0067] The specific process is as follows. In step S311, the MN can configure measurements. To configure measurements, the MN can send an RRC connection reconfiguration message to the UE. To restore the SCG, the MN can send an inter-RAN measurement configuration to the UE. To configure the UL path change configuration requested by the SN, NR RRC information can optionally be sent to the UE together. In step S313, the UE can send an RRC connection reconfiguration complete message to the MN. In step S315, the MN can send a reconfiguration complete message to the SN.

[0068] <3. RAT Inter-measurement Report>

[0069] The MN can configure the SN based on measurement reports received from the UE. When the UE meets the criteria for configuring RAT measurements (e.g., when the reporting criteria are met (e.g., channel quality greater than or equal to a threshold)), the UE can send the measurement results (e.g., measured cell information) to the MN base station. The MN can specify the target SN and SCG based on the corresponding report, and send the measured cell information to the new target SN through the SN modification or SN addition process for the existing target SN. The specific process is as follows.

[0070] In step S321, the UE may send a measurement report to the MN. In this case, the measurement report may include measurement results. The measurement results may include inter-RAT measurement results. The measurement results may include measurement results that depend on the measurement configuration configured through step S311. In step S323, the MN may send an SN modification request message to the SN based on the measurement report. According to an embodiment, the SN modification request message may include information about at least one cell (e.g., a candidate cell list), information about the measurement results (e.g., NR cell measurement results), and X2 reason information. The X2 reason information may indicate SCG mobility. In step S325, the MN may receive a response to the SN modification request from the SN.

[0071] <4. SCG recovery operation and RAT inter-measurement removal>

[0072] The SN can restore the SCG connection based on the obtained measurement information (e.g., step S321). The SN performs an access procedure with the UE through the target PScell ​​(PCell of the SCG) based on the measured cell information. Upon receiving a modification request from the SN, the MN can release the inter-RAT measurement configuration if there is a specific reason. The UE performs an access procedure including a random access procedure upon receiving the reconfiguration message and resumes data transmission / reception. The specific process is as follows.

[0073] In step S331, the SN can perform a recovery procedure. As a typical cell access procedure, the SN can initiate a radio connection recovery procedure through a random access procedure. In step S333, the SN can send information related to the recovery procedure to the MN. For example, the SN can send the UE's SN modification request message to the MN. The information related to the recovery procedure may include the cell used when the SN is coupled to the UE (e.g., the ID of the PSCell). In addition, the information related to the recovery procedure may include an X2 cause (SCG mobility) as the reason for information transmission. Optionally, the SN can send an NR RRC including UL path information to the MN to restore the UL path. In step S335, the MN can remove the measurement configuration according to the SN's request. The MN can identify the cause indication "SCG mobility" transmitted from the SN. When the cause indication "SCG mobility" is identified, the MN can remove the preset measurement configuration (e.g., B1 configuration). In step S337, the MN can send an RRC connection reconfiguration message to the UE. For the RRC connection reconfiguration message, a message including configuration removal (e.g., B1 removal) can be sent to the UE. In this embodiment, the RRC connection reconfiguration message may include the NR RRC configuration (information sent by the SN as an NR base station to the MN for UE configuration). In step S339, the UE may send an RRC connection reconfiguration complete message to the MN. In step S341, the MN may send an SN modification confirmation message to the SN. Subsequently, in step S343, the UE can couple to the target cell of the SCG via a Physical Random Access Channel (PRACH) procedure (e.g., NR PRACH in the case of E-UTRA-NR-Dual Connectivity (EN-DC)).

[0074] Despite Figure 3 The document details the operations of each node to describe the interactions between the MN, SN, and UE. Each procedure for recovering from an SCG fault can be operated independently. That is, the inter-node operations of the procedure can be applied as separate implementations, and unnecessary operations can be omitted in some implementations.

[0075] When an SCG failure occurs in the SN, a more reliable recovery procedure can be performed via signaling with the MN and between the MN and the UE, instead of the SN autonomously performing the recovery procedure via RRE. For example, even if an RLF occurs in the gNB under EN-DC conditions, the UE can be coupled to the gNB's PSCell via signaling between the eNB and the UE. The gNB's PSCell can then be reliably coupled to the UE via a more reliable RRC reconfiguration procedure with the eNB. As another example, consider the case where one gNB and another gNB are coupled via DC. The MN could be a gNB providing a serving cell in frequency range #1 (FR1), and the SN could be a gNB providing a serving cell in frequency range #2 (FR2). In the FR2 case, RLFs may occur frequently due to the high frequency band. In this case, since operations are performed in a relatively low frequency domain, an SCG recovery procedure can be performed for the FR2 gNB via signaling between the UE and the gNB to provide a reliable connection.

[0076] At the same time, it is clear that the same or similar procedure will be followed not only when the SCG of SN fails, but also when the MCG of MN fails. Figure 3 The signaling. According to an embodiment, when an RLF occurs in the gNB acting as the MN in NR-E-UTRA-Dual Connectivity (NE-DC) mode, the eNB acting as the SN can perform a recovery procedure with the UE. Furthermore, according to an embodiment, when an RLF occurs in the cell of the eNB acting as the MN in EN-DC mode, the gNB acting as the SN can perform a recovery procedure with the UE. Since the occurrence of an RLF may not be caused by simple channel quality degradation, but by factors caused by a specific node (e.g., configuration failure, changes in the environment around the corresponding base station, base station failure, etc.), the failure of the SCG or MCG can be effectively corrected by performing a recovery procedure by another node.

[0077] In some embodiments, when a fault occurs in the SCG, the UE may not store the measurement configuration information set in the SCG. In various MR-DC scenarios, such as EN-DC or DC scenarios between FR1 and FR2, when an RLF occurs in the SN, the UE can be configured not to store any settings for the corresponding cell. That is, since the UE does not consider SN-related settings, it may not be easy to find a new cell (NR). Therefore, the UE can receive the measurement configuration information for the RAT of the SN (eNB-RAT inter-eNB measurement configuration information) through a reconfiguration process with another node (eNB). The UE can perform measurements on the PSCell of the SN based on the control of the MN. According to various embodiments, when an RLF occurs in a specific node, measurement configuration information is provided under the control of another node, and a connection is re-established with the specific node based on this information, thereby reducing the possibility of delays in the connection recovery process due to UE limitations.

[0078] Figure 4 Examples of signaling for blacklisted cell management in a wireless communication system according to various embodiments of this disclosure are illustrated. Based on the blacklist (measurement prohibited), operations performed by the MN among the MN, SN, and UE for handling SCG faults in the event of an SCG fault are described.

[0079] like Figure 4 The diagram illustrates a scenario where multiple connections are implemented in a UE. The UE can be coupled to both MN and SN. MN is an LTE base station (or LTEMN), and SN is an NR base station (or NR SN). The UE can be coupled to multiple base stations via EN-DC.

[0080] <1. Track current PSCell information>

[0081] The MN can manage the cell information of the SN, i.e., the SCG cell information. The MN can identify the PScell ​​information of the SCG by tracking information about the cells of the SCG. The specific process is as follows.

[0082] In step S401, the SN can identify its cell information. The cell information of the SN can be the cell information of the SN's SCG. In step S403, the SN can send the SCG cell information to the MN. The cell information can include information about the PSCell, which is the Pcell of the SCG. In some embodiments, the SN can identify information about the PScell ​​coupled to the current UE during initial access and can send it to the MN. Furthermore, in some embodiments, the SN can identify information about the PScell ​​coupled to the current UE whenever the PScell ​​changes and can send it to the MN. Additionally, in some embodiments, the SN can identify information about the PScell ​​coupled to the current UE when a predetermined event is met and can send it to the MN. Additionally, in some embodiments, the SN can periodically identify information about the PScell ​​coupled to the current UE and can send it to the MN. In step S405, the MN can identify the cell (PSCell) information of the SCG. In some embodiments, the MN can detect SCG faults by tracking the SCG cell information.

[0083] <2. SN release, registering the faulty cell to the blacklist>

[0084] Upon detecting an SCG fault, the MN can release the SCG. In this case, the MN can manage the corresponding connection by registering the detected SCG cell in a blacklist and operating a timer. The specific process is as follows.

[0085] In step 411, the RLF of the SCG can occur in the SN. Due to the SCG failure, an SN release is performed. In some embodiments, the MN can detect the SCG failure. In some other embodiments, the SN can detect the SCG failure. When an SCG failure is detected, if the SN release was initiated by the SN, a specific reason is sent to the MN, notifying that the release was caused by the SCG failure.

[0086] In step 413, the MN can identify an SCG fault. The MN can be configured with measurement report events (e.g., B1 events). Configuring measurement report events can mean configuring parameters that constitute predetermined conditions in the measurement report sent to the base station when the UE meets predetermined conditions. According to various embodiments, the MN can register the detected faulty cell to a blacklist. Even if a measurement report from a cell registered in the blacklist is received, the MN can be configured to ignore the measurement report.

[0087] In step S415, the MN can perform an SN release. The MN can perform an SN release caused by an SCG fault. The MN can send a message for SN release to the UE, namely an RRC connection reconfiguration message. The RRC connection reconfiguration message may include an SN release command. The RRC connection reconfiguration message may include inter-RAT measurement configuration (e.g., B1 event configuration).

[0088] In step 417, the MN can detect an SCG fault and can start a timer when performing an SN release initiated by the MN or SN. Here, the timer can be a timer configured for the cell where the SCG fault occurred. The MN can register the PSCell of the SCG in which the fault occurred to a blacklist until the timer expires. Although step 417 is shown to be performed after step 415, the two steps can be performed independently / in parallel.

[0089] In step S419, the UE can receive an RRC connection reconfiguration message from the MN. The UE can recognize an SN release command. The UE can perform an SN release. The UE can recognize a B1 event configuration. The UE can perform measurements on the SCG based on the inter-RAT measurement configuration (e.g., the B1 event configuration).

[0090] <3. B1 Skip Faulty Cells>

[0091] In step S421, the UE performs measurements. When the configured conditions are met (e.g., measurement report: B1 event), the UE can send the measurement results to the MN. When the channel quality (e.g., RSRP, RSRQ) meets the conditions configured for inter-RAT B1 measurements (e.g., entry condition - above threshold, exit condition - below threshold), the UE can send the measured cell information to the MN base station. Even if a measurement report corresponding to the blacklist is received, the MN can ignore it during timer operation. That is, since it is before the timer expires, the UE can ignore the measurement results of the PSCell when the measurement results include those of cells registered to the blacklist (i.e., PSCells where RLF occurred).

[0092] <4. B1 Acceptance After Timer Expiration>

[0093] In step S431, the timer may expire. When the timer expires, the MN may remove the PCell (PSCell) of the SCG included in the blacklist. Subsequently, in step S433, the MN may receive measurement reports for the corresponding cell of the UE. In step S440, the MN may perform the SN addition procedure based on the measurement reports.

[0094] Despite Figure 4 The document details the operations of each node to describe the interactions between the MN, SN, and UE. Each process for recovering from an SCG fault can be performed independently. That is, the operations between nodes in the process can be applied as separate implementations, and unnecessary operations can be omitted in some implementations. For example, depending on when a measurement report is received, the MN can execute step S440 after step S421.

[0095] Furthermore, although step S440 is in Figure 4 The process described is executed by the MN to establish a connection with the UE, but the signaling between the MN and SN can be defined as specific operations of the MN and SN. For example, signaling can be transmitted via... Figure 3 The steps S323 and S325 will be used as examples to illustrate this.

[0096] When an SCG failure occurs in the SN, a more reliable recovery process can be performed via signaling with the MN and between the MN and the UE, instead of the SN autonomously performing the recovery process via RRE. For example, even if an RLF occurs in the gNB under EN-DC conditions, the eNB can configure the B1 event and perform measurement reporting with the UE based on it. Additionally, the eNB can operate timers and blacklists to couple the UE to the gNB's PSCell. The gNB can reliably couple to the UE via a more reliable RRC reconfiguration process with the eNB. As another example, consider the case where one gNB and another gNB are coupled via DC. The MN could be the gNB providing the serving cell for frequency range #1 (FR1), and the SN could be the gNB providing the serving cell for frequency range #2 (FR2). In the case of FR2, RLFs may occur frequently due to the high frequency band. In this case, since operations are performed in a relatively low frequency domain, cell measurement information can be configured for the FR2 gNB via signaling between the UE and the gNB to provide a reliable connection. Based on the measurement results based on the measurement configuration information, the FR1 gNB can perform an SCG recovery process for FR2.

[0097] At the same time, it is clear that the same or similar procedure will be followed not only when the SCG of SN fails, but also when the MCG of MN fails. Figure 4 The signaling. According to an embodiment, when an RLF occurs in a gNB acting as the MN in NE-DC mode, the eNB acting as the SN can perform a recovery procedure with the UE. Furthermore, according to an embodiment, when an RLF occurs in a cell of an eNB acting as the MN in EN-DC mode, the gNB acting as the SN can perform a recovery procedure with the UE through timer operation and blacklist operation. Since the occurrence of an RLF may not be caused by simple channel quality degradation, but by factors caused by specific nodes (e.g., configuration failure, changes in the environment around the corresponding base station, base station failure, etc.), the failure of the SCG or MCG can be effectively corrected by performing a recovery procedure by another node.

[0098] In some embodiments, when a fault occurs in the SCG, the UE may not store the measurement configuration information set in the SCG. In various MR-DC scenarios, such as EN-DC or DC scenarios between FR1 and FR2, the UE may not have the ability to store SCG information. That is, when an RLF occurs in the SN, the UE can be configured not to store any settings for the corresponding cell. Since the UE cannot consider SN-related settings, it may not be easy to find a new cell (NR). The UE may need to obtain the measurement configuration for finding a new cell through a reconfiguration process with another node (eNB). The UE can receive measurement configuration information for the RAT of the SN (eNB RAT inter-measurement configuration information). The UE can perform measurements on the PSCell of the SN based on the control of the MN. According to various embodiments, when an RLF occurs in a particular node, the UE obtains measurement configuration information from another previously coupled node, thereby solving the problem caused by the limited capabilities of existing UEs.

[0099] Figure 5 Another example of signaling for blacklisted cell management in a wireless communication system according to various embodiments of this disclosure is illustrated. Based on the blacklist (measurement prohibited), operations performed by the MN for handling SCG faults in the event of an SCG fault are described between the MN, SN, and UE.

[0100] Reference Figure 5 This describes the scenario of multiple connections being implemented in the UE. The UE can be coupled to both the MN and SN. The MN is an LTE base station (or LTEMN), and the SN is an NR base station (or NR SN). The UE can be coupled to multiple base stations via EN-DC.

[0101] <Tracking current PSCell ID information>

[0102] The MN can manage the cell information of the SN, i.e., the SCG cell information. The MN can identify the PScell ​​information of the SCG by tracking information about the cells of the SCG. The specific process is as follows.

[0103] In step S501, the SN can identify the cell information of the SN. The cell information of the SN can be the cell information of the SCG of the SN. In step S503, the SN can send the SCG cell information to the MN. The cell information can include information about the PSCell that is the PCell of the SCG. In some embodiments, the SN can identify the information of the PSCell coupled to the current UE in the initial access and send it to the MN. In addition, in some embodiments, whenever the PSCell changes, the SN can identify the information of the PSCell coupled to the current UE and send it to the MN. In addition, in some embodiments, the SN can identify the information of the PSCell coupled to the current UE when a predetermined event is satisfied and send it to the MN. Additionally, in some embodiments, the SN can periodically identify the information of the PSCell coupled to the current UE and send it to the MN. Corresponding to Figure 4 the operations of the MN and SN can also be applied to Figure 5 the MN and SN in the same or similar manner.

[0104] <The SN releases and adds the faulty cell to the blacklist>

[0105] After detecting an SCG failure, the MN can release the SCG. In this case, the MN can manage the corresponding connection by registering the cell where the SCG is detected in the blacklist and operating a timer. The specific process is as follows.

[0106] In step 511, an RLF of the SCG can occur in the SN. Due to the SCG failure, an SN release is performed. In some embodiments, the MN can detect the SCG failure. In some other embodiments, the SN can detect the SCG failure. When the SCG failure is detected, if the SN release is initiated by the SN, a specific reason is sent to the MN to notify the release situation caused by the SCG failure.

[0107] In step 513, the MN can identify the SCG failure and start a timer when performing an SN release initiated by the MN or the SN. Here, the timer can be a timer configured for the cell where the SCG failure occurs. The MN can register the PSCell of the SCG where the failure occurs in the blacklist until the timer expires. At the same time, different from Figure 4 the MN may not configure a measurement report event (e.g., an inter-RAT event (e.g., a B1 event)). That is, the MN can perform an SN release without configuring an event for measurement report triggering.

[0108] In step S515, the MN can perform an SN release. The MN can perform an SN release caused by an SCG fault. The MN can send a message for SN release to the UE, namely an RRC connection reconfiguration message. The RRC connection reconfiguration message may include an SN release command. The UE can receive the RRC connection reconfiguration message from the MN. The UE can recognize the SN release command. The UE can perform an SN release.

[0109] <B1 configuration after timer expiration>

[0110] In step S521, the timer may expire. When the timer expires, the MN may configure the inter-RAT measurement configuration. In step S523, the MN may send an RRC connection reconfiguration including the inter-RAT measurement configuration to the UE. In step S525, the UE may send an RRC connection reconfiguration completion message to the MN. Subsequently, in step S527, the MN may perform an SN addition procedure based on the measurement report. Specifically, when the channel quality (e.g., RSRP, RSRQ) meets the conditions for configuring inter-RAT B1 measurements (e.g., entry condition - above threshold, exit condition - below threshold), the UE may send the measured cell information to the MN base station. The MN may perform an SN addition procedure based on the corresponding measurement report and SN.

[0111] Despite Figure 5 The document details the operations of each node to describe the interactions between the MN, SN, and UE. Each procedure for recovering from an SCG fault can be operated independently. In other words, the operations between nodes within a procedure can be applied as separate implementations, and unnecessary operations can be omitted in some implementations.

[0112] Furthermore, although step S520 is in Figure 5 The process described is executed by the MN to establish a connection with the UE, but the signaling between the MN and SN can be defined as specific operations of the MN and SN. For example, signaling can be transmitted via... Figure 3 The steps S323 and S325 will be used as examples to illustrate this.

[0113] When an SCG failure occurs in the SN, a more reliable recovery process can be performed via signaling with the MN and between the MN and the UE, rather than the SN autonomously performing the recovery process via RRE. For example, even if an RLF occurs in the gNB under EN-DC conditions, the eNB can operate timers and blacklists to couple the UE to the gNB's PSCell. Subsequently, the eNB can configure B1 events, and based on this, can perform measurement reporting with the UE. The gNB can reliably couple to the UE via a more reliable RRC reconfiguration process with the eNB. As another example, consider the case where one gNB and another gNB are coupled via DC. The MN could be a gNB providing a serving cell in frequency range #1 (FR1), and the SN could be a gNB providing a serving cell in frequency range #2 (FR2). In the FR2 case, RLFs may occur frequently due to the high-frequency band. In this case, since operations are performed in a relatively low frequency domain, cell measurement information can be configured for the FR2 gNB via signaling between the UE and the gNB to provide a reliable connection. Based on the measurement results using the measurement configuration information, FR1's gNB can perform the SCG recovery process for FR2.

[0114] At the same time, it is clear that the same or similar procedure will be followed not only when the SCG of SN fails, but also when the MCG of MN fails. Figure 5 The signaling. According to an embodiment, when an RLF occurs in a gNB acting as the MN in NE-DC mode, the eNB acting as the SN can perform a recovery procedure with the UE. Furthermore, according to an embodiment, when an RLF occurs in a cell of an eNB acting as the MN in EN-DC mode, the gNB acting as the SN can perform a recovery procedure with the UE through timer operation and blacklist operation. Since the occurrence of an RLF may not be caused by simple channel quality degradation, but by factors caused by specific nodes (e.g., configuration failure, changes in the environment around the corresponding base station, base station failure, etc.), the failure of the SCG or MCG can be effectively corrected by performing a recovery procedure by another node.

[0115] In some embodiments, when an SCG failure occurs, the UE can be configured not to store the measurement configuration information set in the SCG. In the event of an SCG failure, the UE may not easily find a new cell (NR) because it cannot consider settings associated with the SN. Therefore, the UE can perform measurements on the SN's PSCell based on the MN's control signaling (including RRC messages for inter-RAT measurement configuration). According to various embodiments, when an RLF occurs in a specific node, the UE obtains measurement configuration information from another previously coupled node, thereby addressing the problem caused by the limited capabilities of existing UEs.

[0116] Figure 6Examples of signaling for controlling link failures in a secondary node (SN) in a wireless communication system according to various embodiments of this disclosure are shown. Figure 6 This describes the operations performed by the SN to handle SCG failures in the event of an SCG failure between the MN, SN, and UE. This is a scenario where multiple connections are implemented within the UE. The UE can be coupled to both the MN and SN. The UE can be coupled to the Data Radio Bearer (DRB) active in both the MN and SN. The UE can be coupled to the SN at the Radio Resource Control (RRC) / Packet Data Convergence Protocol (PDCP) level.

[0117] Reference Figure 6 In step S600, the UE can couple to the base station. That is, this is a case where multiple connections are implemented within the UE. The UE can couple to the MN and SN. The UE can couple to the DRB activated in the MN and SN. The UE can couple to the SN at the RRC / PDCP level.

[0118] In step S610, the SN can detect an SCG fault. The SN can detect an SCG fault based on information obtained from the UE, or it can autonomously detect whether specified conditions are met or an SCG fault is detected by inputting information to other nodes.

[0119] In step S620, the SN can initiate a reconnection procedure. The SN can identify the PSCell for reconnection. The SN can detect SCG faults by receiving SCG fault information. In this case, when the measurement result is included in the SCG fault information, a reconnection procedure (direct resynchronization procedure) can be performed. The SN can perform a reconnection procedure with the cell included in the measurement result. That is, the cell identifier of the candidate PSCell can be included in the SCG fault information. Here, the candidate PSCell can be the cell with the highest channel quality among the target cells being measured (e.g., the cell with the highest RSRP) and satisfy the minimum channel quality value. When the measurement result does not include SCG fault information, the SN can instruct a reconnection procedure with the existing PSCell. The SN can initiate a reconnection procedure with the cell with the highest channel quality among the measured cells.

[0120] The SN of the PSCell identified for the reconnection process can perform the connection procedure with the UE through the MN. Specifically, the MN, SN, and UE can perform the following operations.

[0121] In step S631, the SN may send an SN modification request message to the MN. The SN modification request message may include the X2 reason and configuration information for the target PSCell. The X2 reason may be set to "SCG Mobility". In step S633, the MN may send an RRC connection reconfiguration message to the UE. In this case, for the SN (NR base station), in some embodiments, the RRC connection reconfiguration message may include an RRC reconfiguration message for NR. In step S635, the UE may send an RRC connection reconfiguration complete message to the MN. In this case, for the SN (NR base station), in some embodiments, the RRC connection reconfiguration complete message may include an RRC reconfiguration complete message for NR.

[0122] In step S637, the MN can send an SN modification confirmation message to the SN. Subsequently, in step S639, the UE can perform an access procedure with the SN. The UE can perform the access procedure based on the PSCell information transmitted from the SN through the MN. The UE can perform data transmission and reception with the SN in the corresponding PSCell through the NR RACH procedure and RRC recovery procedure for the corresponding cell.

[0123] Despite Figure 6 The operation of each node is described in detail to illustrate the operation between the MN, SN, and UE; however, each procedure for recovering from an SCG fault can be operated independently. That is, the inter-node operation of the procedure can be applied as a single embodiment, and unnecessary operations can be omitted in some embodiments.

[0124] Furthermore, although step S637 is in Figure 6 The process described is executed by the MN to establish a connection with the UE, but the signaling between the MN and SN can be defined as specific operations of the MN and SN. For example, signaling can be transmitted via... Figure 3 Steps S323 and S325 Figure 4 The steps S421 to S440 and S521 to S527 are illustrated with examples.

[0125] The case where MN is an eNB acting as an LTE base station and SN is a gNB acting as an NR base station is described in this invention as an EN-DC environment. However, it is clear that embodiments of this disclosure can also be implemented in different MR-DC environments, similar to the NR-DC environment, i.e., NR-NR. Additionally, as a measurement reporting event between two base stations, the B1 event for configuring inter-RAT measurements has been exemplarily described. The B1 event can be a reporting condition configured to report measurement results of neighboring cells that have a different RAT than one with channel quality exceeding a threshold. However, this is merely an exemplary description of the event in the EN-DC case for ease of illustration; embodiments of the invention can also be implemented using other measurement reporting conditions besides the B1 event.

[0126] Figure 7 The functional structure of a base station 110 in a wireless communication system according to various embodiments of the present disclosure is shown. Figure 7 The exemplary structure can be understood as the structure of base station 110. In the following text, the terms "...unit", "...device", etc., mean a unit that processes at least one function or operation, and can be implemented in hardware or software or a combination of hardware and software.

[0127] Reference Figure 7 The base station 110 includes a wireless communication unit 701, a backhaul communication unit 703, a storage unit 705, and a control unit 707.

[0128] The wireless communication unit 701 performs the function of transmitting and receiving signals through a radio channel. For example, the wireless communication unit 701 performs the conversion function between baseband signals and bitstreams according to the physical layer standard of the system. For example, in data transmission, the wireless communication unit 701 generates complex symbols by encoding and modulating the transmitted bitstream. Furthermore, in data reception, the wireless communication unit 701 recovers the received bitstream by demodulating and decoding the baseband signal. In addition, the wireless communication unit 701 upconverts the baseband signal into a radio frequency (RF) signal and then transmits it through the antenna, and downconverts the RF signal received through the antenna into a baseband signal.

[0129] Therefore, the wireless communication unit 701 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. Furthermore, the wireless communication unit 701 may include multiple transmit / receive paths. Additionally, the wireless communication unit 701 may include at least one antenna array composed of multiple antenna elements. In terms of hardware, the wireless communication unit 701 may be composed of digital units and analog units, and the analog units may be composed of multiple sub-units depending on the operating power, operating frequency, etc. According to various embodiments, the wireless communication unit 701 may include a beamforming unit, i.e., a beamforming unit. For example, the wireless communication unit 701 may include a massive MIMO unit (MMU).

[0130] The wireless communication unit 701 can transmit / receive signals. For this purpose, the wireless communication unit 701 may include at least one transceiver. For example, the wireless communication unit 701 can transmit synchronization signals, reference signals, system information, messages, control information, or data. Furthermore, the wireless communication unit 701 can perform beamforming. To assign the directionality to the signals to be transmitted / received according to the settings of the control unit 707, the wireless communication unit 701 can apply beamforming weights to the signals. According to an embodiment, the wireless communication unit 701 can generate a baseband signal based on scheduling results and transmit power calculation results. Furthermore, the RF unit in the wireless communication unit 701 can transmit the generated signal via an antenna.

[0131] The wireless communication unit 701 transmits and receives signals as described above. Therefore, the wireless communication unit 701 can be referred to as a transmitter, receiver, or transceiver. Furthermore, in the following description, the transmission and reception performed via a radio channel are used to imply that the above-described processing is performed by the wireless communication unit 701.

[0132] The backhaul communication unit 703 provides an interface for communicating with different nodes in the network. That is, the backhaul communication unit 703 converts bitstreams sent from base station 110 to different nodes (e.g., different access nodes, different base stations, upper-layer nodes, core network, etc.) into physical signals, and converts physical signals received from different nodes into bitstreams. According to various embodiments, the backhaul communication unit 703 can send messages to another base station (e.g., any SN). In some embodiments, the message may include an SN modification request message and a response message to it. Furthermore, the message may include cell information. In some embodiments, the message may include information about the currently operating cell (e.g., current PSCell information). Additionally, in some embodiments, the cell information may include information about the target cell for reconnection. The target cell for reconnection may be a PSCell candidate cell. The cell information may indicate the cell in the form of a Cell Global Identifier (CGI). For example, the message may include an NR-CGI to indicate a candidate cell for the target PSCell of an NR base station.

[0133] Storage unit 705 stores data such as basic programs, application programs, and configuration information for the operation of base station 110. Storage unit 705 may include memory. Storage unit 705 may be composed of volatile memory, non-volatile memory, or a combination of volatile memory and non-volatile memory. In addition, storage unit 705 can provide stored data according to requests from control unit 707.

[0134] Control unit 707 controls the overall operation of base station 110. For example, control unit 707 can send and receive signals via communication unit 701 or backhaul communication unit 703. Furthermore, control unit 707 writes and reads data in storage unit 705. Additionally, control unit 707 can perform the functions of the protocol stack required in the communication specification. For this purpose, control unit 707 may include at least one processor. In some embodiments, control unit 707 can perform MN or SN operations. Control unit 707 can detect the occurrence of RLF in a cell. Control unit 707 can detect cell group faults. Control unit 707 can configure inter-RAT measurements. Control unit 707 can control the registration / removal of blacklists. Control unit 707 can start a timer or detect the end of a timer. Components for each operation of control unit 707 may be commands / codes or storage space storing commands / codes that reside at least temporarily in control unit 707, or may be part of the circuitry constituting control unit 707. Meanwhile, according to another embodiment, the scheduler and transmit power calculation unit can be implemented independently in separate devices. According to various embodiments, the control unit 707 can control the base station 110 to perform operations based on various embodiments described below.

[0135] Figure 7 The structure of the base station 110 shown is merely an example of a base station, and examples of base stations implementing the various embodiments of this disclosure are not limited to this. Figure 7 The structure is shown. In other words, the structure can be partially added to, deleted from, or changed according to various embodiments.

[0136] Although the base station is Figure 7 While described as an entity, the invention is not limited thereto. Base stations according to various embodiments of this disclosure can be implemented to constitute access networks that have both integrated and distributed deployments. According to embodiments, a base station can be divided into a central unit (CU) and a digital unit (DU). The CU can be implemented to perform upper-layer functions (e.g., packet convergence protocol (RRC)), and the DU can be implemented to perform lower-layer functions (e.g., media access control (MAC) and physical (PHY)). The DUs of the base station can constitute beam coverage over a radio channel.

[0137] Figure 8 The functional structure of a UE in a wireless communication system according to various embodiments of the present disclosure is shown. Figure 8 The exemplary structure can be understood as the structure of UE 120. In the following text, the terms "...unit", "...device", etc., refer to a unit that processes at least one function or operation, and can be implemented in hardware or software or a combination of hardware and software.

[0138] Reference Figure 8UE 120 includes a communication unit 801, a storage unit 803, and a control unit 805.

[0139] The communication unit 801 performs the function of transmitting and receiving signals via a radio channel. For example, the communication unit 801 performs the conversion function between baseband signals and bit streams according to the physical layer standard of the system. For example, in data transmission, the communication unit 801 generates complex symbols by encoding and modulating the transmitted bit stream. Furthermore, in data reception, the communication unit 801 recovers the received bit stream by demodulating and decoding the baseband signal. In addition, the communication unit 801 upconverts the baseband signal into an RF signal and transmits it through an antenna, and downconverts the RF signal received through the antenna into a baseband signal. For example, the communication unit 801 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, etc.

[0140] Furthermore, the communication unit 801 may include multiple transmit / receive paths. Additionally, the communication unit 801 may include antenna elements. The communication unit 801 may include at least one antenna array composed of multiple antenna elements. From a hardware perspective, the communication unit 801 may be composed of digital circuits and analog circuits (e.g., radio frequency integrated circuits (RFICs)). Here, the digital circuits and analog circuits may be implemented in a single package. Furthermore, the communication unit 801 may include multiple RF chains. Furthermore, the communication unit 801 may perform beamforming. In order to assign directivity to the signal to be transmitted / received according to the settings of the control unit 805, the communication unit 801 may apply beamforming weights to the signal. According to an embodiment, the communication unit 801 may include a radio frequency (RF) block (or RF unit). The RF block may include a first RF circuit associated with an antenna and a second RF circuit associated with baseband processing. The first RF circuit may be referred to as a radio frequency antenna (RF-A). The second RF circuit may be referred to as an RF baseband (RF-B).

[0141] Additionally, the communication unit 801 can transmit / receive signals. For this purpose, the communication unit 801 may include at least one transceiver. The communication unit 801 can receive downlink signals. Downlink signals may include synchronization signals (SS), reference signals (RS) (e.g., cell-specific reference signals (CRS), demodulation (DM)-RS), system information (e.g., MIB, SIB, residual system information) (RMSI), other system information (OSI), configuration messages, control information, or downlink data, etc. Additionally, the communication unit 801 can transmit uplink signals. Uplink signals may include random access related signals (e.g., random access preamble (RAP) (message 1 (Msg1), message 3 (Msg3))), reference signals (e.g., sounding reference signals (SRS), DM-RS), or power headroom reports (PHR), etc.

[0142] Additionally, the communication unit 801 may include different communication modules to process signals in different frequency bands. Furthermore, the communication unit 801 may include multiple communication modules to support a variety of different radio access technologies. For example, different radio access technologies may include Bluetooth Low Energy (BLE), Wi-Fi, WiGig, cellular networks (e.g., LTE, NR), etc. Furthermore, different frequency bands may include ultra-high frequency (SHF) bands (e.g., 2.5 GHz, 5 GHz) and millimeter wave bands (e.g., 38 GHz, 60 GHz, etc.). Moreover, the communication unit 801 can use the same type of radio access technology in different frequency bands (e.g., unlicensed bands used for Licensed Assisted Access (LAA) and Citizens Broadband Radio Service (CBRS) (e.g., 3.5 GHz)).

[0143] Communication unit 801 transmits and receives signals as described above. Therefore, communication unit 801 can be referred to as a transmitter, receiver, or transceiver. Furthermore, in the following description, the transmission and reception performed via a radio channel are used to imply that the above-described processing is performed by communication unit 801.

[0144] Storage unit 803 stores data such as basic programs, application programs, and configuration information used for the operation of UE 120. Storage unit 803 may be composed of volatile memory, non-volatile memory, or a combination of volatile and non-volatile memory. Furthermore, storage unit 803 can provide stored data upon request from control unit 805. According to various embodiments, storage unit 803 may store direction information for each beam of a beamset to be operated in UE 120 or for each beam of an auxiliary beam pair.

[0145] Control unit 805 controls the overall operation of UE 120. For example, control unit 805 can send and receive signals via communication unit 801. Furthermore, control unit 805 writes and reads data in storage unit 803. Additionally, control unit 805 can perform the functions of the protocol stack required in the communication specification. For this purpose, control unit 805 may include at least one processor. Control unit 805 may include at least one processor or microprocessor, or may be part of a processor. Furthermore, communication unit 801 and part of control unit 805 may be referred to as CP. Control unit 805 may include various modules for performing communication. According to various embodiments, control unit 805 can control the UE to perform operations based on the various embodiments described above. Control unit 805 can detect the occurrence of RLF in the cell. Control unit 805 can perform measurements. Control unit 805 can detect whether measurement reporting conditions are met. Control unit 805 can execute a measurement report including measurement results. Control unit 805 can perform the access procedure with the cell. Control unit 805 can perform measurements.

[0146] Even when a Recurrent Fault (RLF) occurs in the secondary node (SN) during dual connectivity between heterogeneous or homogeneous RATs in the UE via measurement reporting and signaling procedures between the MN and SN, timer operations, etc., recovery and reconnection procedures can be configured for this purpose. Based on these procedures, performance improvements can be expected compared to conventional techniques because effective fault management can be achieved through the processing operations of existing cells and bearers under base station control.

[0147] Various embodiments of this disclosure can be applied to multiple radio dual connectivity (MR-DC), including: Evolved Universal Terrestrial Radio Access-New Radio Dual Connectivity (EN-DC) for establishing a connection to the 4G core network between a 4G primary cell group and a 5G secondary cell group as defined in the 3GPP standard; NG-RAN Evolved Universal Terrestrial Radio Access-New Radio Dual Connectivity (NGEN-DC) for establishing a connection to the 5G core network between a 4G primary cell group and a 5G secondary cell group; New Radio Evolution Universal Terrestrial Radio Access Dual Connectivity (NE-DC) for establishing a connection to the 5G core network between a 4G secondary cell group and a 5G primary cell group; and multiple radio dual connectivity (MR-DC) for establishing a connection between a 5G cell group and another 5G cell group.

[0148] A method for configuring a base station in a wireless communication system with a primary cell group (MCG) according to the above-disclosed embodiments may include detecting a fault (PScell) in the primary cell (PCell) of a secondary cell group (SCG), sending inter-Radio Access Technology (RAT) measurement configuration information to a terminal based on the detection, and sending information about cells identified based on the measurement configuration information to the base station configured with the SCG.

[0149] In an embodiment, information about the identified cell may include information about at least one cell, information about measurement results based on measurement configuration information, and X2 cause information.

[0150] In an embodiment, detection may include receiving information about SCG failures from a terminal or a base station configured with SCG.

[0151] In an embodiment, the method may further include receiving a measurement report of measurement configuration information from a terminal, and identifying a cell based on the measurement report.

[0152] In an embodiment, the method may further include receiving information related to the recovery process from a base station configured with an SCG. The information related to the recovery process may include the identifier (ID) of the PSCell or an X2 reason.

[0153] In an embodiment, the method may further include sending a removal message, including measurement configuration information, to the terminal based on information related to the recovery process.

[0154] In an embodiment, the method may further include receiving a response from the terminal to a message that includes the removal of measurement configuration information, and sending a modification confirmation message to the base station configured with SCG based on the response.

[0155] In a wireless communication system according to the embodiments disclosed above, a base station configured with an MCG may include at least one transceiver and at least one processor. The at least one processor may be configured to detect PScell ​​faults, send inter-AT measurement configuration information to a terminal based on the detection, and send information about cells identified based on the measurement configuration information to the base station configured with an SCG.

[0156] In an embodiment, information about the identified cell may include information about at least one cell, information about measurement results based on measurement configuration information, and X2 cause information.

[0157] In an embodiment, at least one processor may be configured to receive information about SCG failures from a terminal or a base station configured with an SCG.

[0158] In an embodiment, at least one processor may be configured to receive a measurement report of measurement configuration information from a terminal and identify a cell based on the measurement report.

[0159] In this embodiment, at least one processor may be configured to receive information related to the recovery process from a base station configured with an SCG. The information related to the recovery process may include the PSCell ID or the X2 cause.

[0160] In one embodiment, at least one processor may be configured to send a removal message, including measurement configuration information, to the terminal based on information related to the recovery process.

[0161] In one embodiment, at least one processor may be configured to receive a response from the terminal to a message that includes the removal of measurement configuration information, and to send a modification confirmation message to the base station configured with SCG based on the response.

[0162] A method for configuring a base station with an SCG in a wireless communication system may include: detecting a fault in a PScell, identifying a cell based on the detection, and performing a connection process with a terminal by sending information about the cell to a base station configured with an MCG.

[0163] In a wireless communication system according to the embodiments disclosed above, a base station configured with an SCG may include at least one transceiver and at least one processor. The at least one processor may be configured to detect PScell ​​faults, identify a cell based on the detection, and perform a connection process with a terminal by sending information about the cell to the base station configured with an MCG.

[0164] Furthermore, although the expressions “greater than” or “less than” are used in this disclosure to determine whether a particular condition is met (or achieved), this is for illustrative purposes only and does not exclude expressions “greater than or equal to” or “less than or equal to”. A condition described as “greater than or equal to” can be replaced with “greater than”. A condition described as “less than or equal to” can be replaced with “less than”. A condition described as “greater than or equal to and less than” can be replaced with “greater than and less than or equal to”.

[0165] The methods based on the claims of this disclosure and / or the embodiments disclosed in the specification can be implemented in hardware, software, or a combination of both.

[0166] When implemented in software, a computer-readable recording medium may be provided for storing one or more programs (i.e., software modules). The one or more programs stored in the computer-readable recording medium are configured to be executed by one or more processors in an electronic device. The one or more programs include instructions for allowing the electronic device to perform methods based on embodiments disclosed in the claims and / or specification of this disclosure.

[0167] The program (i.e., 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, compressed optical disc-ROM (CD-ROM), digital versatile optical disc (DVD), or other forms of optical storage devices, as well as magnetic tape. Optionally, the program can be stored in a memory configured with all or part of these storage media. Furthermore, the number of configured memories can be multiple.

[0168] Furthermore, the program can be stored in an attachable storage device that can be accessed by the electronic device via a communication network such as the Internet, intranet, local area network (LAN), wide area network (WLAN), or storage area network (SAN), or via a communication network configured with a combination of networks. The storage device can access the device used to execute embodiments of this disclosure via an external port. Additionally, an attached storage device on the communication network can access the device used to execute embodiments of this disclosure.

[0169] In the specific embodiments of the present invention described above, the components included in the present invention are expressed in a singular or plural form according to the specific embodiments presented herein. However, the singular or plural form is suitably chosen for ease of explanation, and therefore the various embodiments of this disclosure are not limited to a single or multiple components. Thus, components expressed in a plural form may also be expressed in a singular form, and vice versa.

[0170] Although this disclosure has been shown and described with reference to certain preferred embodiments thereof, those skilled in the art will understand that various changes in form and detail may be made therein without departing from the spirit and scope of the disclosure as defined by the appended claims. Therefore, the scope of the invention is defined not by its detailed description but by the appended claims, and all differences within the scope equivalent to that scope will be interpreted as included in the invention.

Claims

1. A method performed by a first base station in a wireless communication system, wherein a primary cell group (MCG) is configured, the method comprising: Identify SCG faults associated with the secondary cell group SCG; A first Radio Resource Control (RRC) connection reconfiguration message, including configuration information for measurement, is sent to the User Equipment (UE) associated with the SCG fault. Receive a measurement report based on the configuration information from the UE; Send a first auxiliary node modification request message to the second base station, which is configured with the SCG, including information about the candidate cell list and measurement results based on the measurement report; Receive from the second base station a message including information about the target cell associated with the SCG recovery of the UE; as well as A second RRC connection reconfiguration message, including information about the target cell, is sent to the UE.

2. The method according to claim 1, wherein, Identifying SCG faults associated with the SCG includes: Receive SCG fault information associated with the SCG from the UE or the second base station. The SCG fault information includes the cause of the SCG fault.

3. The method according to claim 2, wherein, upon receiving the SCG fault information from the UE, Send a second auxiliary node modification request message including the SCG fault information to the second base station; and Receive a secondary node modification confirmation message from the second base station, which includes information for path switching.

4. The method according to claim 2, wherein, When the SCG fault information is received from the second base station, the SCG fault information includes the cause of the SCG fault.

5. The method according to claim 1, wherein, The second RRC connection reconfiguration message includes information about the removal of the measurement.

6. The method according to claim 1, further comprising: Receive an RRC connection reconfiguration complete message from the UE; as well as Send a message to the second base station indicating that the secondary node reconfiguration is complete.

7. The method according to claim 1, wherein, The first base station is an eNodeB (eNB), and the second base station is a gNodeB.

8. A first base station in a wireless communication system configured with a primary cell group (MCG), the first base station comprising: transceiver; A memory that stores one or more computer programs; as well as One or more processors, which are communicatively coupled to the transceiver and the memory, One or more of the programs include computer-executable instructions that, when executed individually or jointly by the one or more processors, cause the first base station to: Identify SCG faults associated with the secondary cell group SCG; A first Radio Resource Control (RRC) connection reconfiguration message, including configuration information for measurement, is sent to the User Equipment (UE) associated with the SCG fault. Receive a measurement report based on the configuration information from the UE; Send a first auxiliary node modification request message to the second base station, which is configured with the SCG, including information about the candidate cell list and measurement results based on the measurement report; Receive from the second base station a message including information about the target cell associated with the SCG recovery of the UE; and A second RRC connection reconfiguration message, including information about the target cell, is sent to the UE.

9. The first base station according to claim 8, wherein, When the computer-executable instructions are executed individually or jointly by the one or more processors, the first base station also causes the first base station to: Receive SCG fault information associated with the SCG from the UE or the second base station. The SCG fault information includes the cause of the SCG fault.

10. The first base station according to claim 9, wherein, When the computer-executable instructions are executed individually or jointly by the one or more processors, the first base station also causes the first base station to: In the case of receiving the SCG fault information from the UE Send a second auxiliary node modification request message including the SCG fault information to the second base station; and Receive a secondary node modification confirmation message from the second base station, which includes information for path switching.

11. The first base station according to claim 9, wherein, When the SCG fault information is received from the second base station, the SCG fault information includes the cause of the SCG fault.

12. The first base station according to claim 8, wherein, The second RRC connection reconfiguration message includes information about the removal of the measurement.

13. The first base station according to claim 8, wherein, When the computer-executable instructions are executed individually or jointly by the one or more processors, the first base station also causes the first base station to: Receives an RRC connection reconfiguration complete message from the UE; and Send a message to the second base station indicating that the secondary node reconfiguration is complete.

14. The first base station according to claim 8, wherein, The first base station is an eNodeB (eNB), and the second base station is a gNodeB.

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