Apparatus and method for transmitting status information in a wireless communication system

Abstract

The present disclosure relates to providing a pre-fifth generation (5G) or 5G communication system for supporting higher data rates than fourth generation (4G) communication systems such as long term evolution (LTE). According to various embodiments of the present disclosure, a method for operating a user equipment (UE) supporting carrier aggregation (CA) with a primary cell group (MCG) and a secondary cell group (SCG) in a wireless communication system is provided. The method includes: detecting a radio link failure (RLF) of the MCG; when the RLF of the MCG is detected, determining whether to suspend transmission to the SCG; and when it is determined that transmission to the SCG is suspended, initiating a connection reestablishment process.

Description

Technical Field

[0001] The present disclosure relates generally to wireless communication systems, and more particularly, to an apparatus and method for transmitting status information in a wireless communication system. Background Art

[0002] In order to meet the increased demand for wireless data services since the deployment of the fourth generation (4G) communication system, efforts have been made to develop improved fifth generation (5G) or pre-5G communication systems. Therefore, 5G or pre-5G communication systems are also referred to as 'beyond 4G networks' or 'post-Long Term Evolution (LTE) systems'.

[0003] 5G communication systems are considered to be implemented with higher frequency (millimeter wave, mmWave) bands, such as 28GHz or 60GHz bands, to achieve higher data rates. In order to reduce the propagation loss of radio waves and increase the transmission distance, beamforming, massive multiple input multiple output (MIMO), full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and massive antenna technology are discussed in 5G communication systems.

[0004] In addition, in 5G communication systems, development of system network improvements is being carried out based on advanced small cells, cloud radio access networks (RAN), ultra-dense networks, device-to-device (D2D) communications, wireless backhaul, mobile networks, cooperative communications, coordinated multi-point (CoMP), receiving-end interference cancellation, etc.

[0005] In the 5G system, hybrid frequency shift keying (FSK) and quadrature amplitude modulation (FQAM) and sliding window superposition coding (SWSC) as advanced coding modulation (ACM) have been developed, as well as filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA) and sparse code multiple access (SCMA) as advanced access technologies. In a wireless communication system, a terminal can detect a specific state and can send a message for reporting state information. Such state information may include a wireless connection state or a quality state such as quality of service (QoS). The state information may be received by a base station or another terminal and may be processed to improve the state.

[0006] The above information is presented as background information only to assist with an understanding of the present disclosure. No determination is made, and no assertion is made, as to whether any of the above may be applicable as prior art with respect to the present disclosure. Summary of the invention

[0007] Technical Solution

[0008] Based on the above discussion, the present disclosure provides an apparatus and method for transmitting status information in a wireless communication system.

[0009] In addition, the present disclosure provides an apparatus and method for transmitting a report of a Master Cell Group (MCG) Radio Link Failure (RLF) when an MCG RLF occurs in a wireless communication system.

[0010] In addition, the present disclosure provides an apparatus and method for satisfying Quality of Service (QoS) requirements in Vehicle-to-Everything (V2X) communications in a wireless communication system.

[0011] According to various embodiments of the present disclosure, a method for operating a user equipment (UE) supporting carrier aggregation (CA) with a primary cell group (MCG) and a secondary cell group (SCG) in a wireless communication system is provided. The method includes: detecting a radio link failure (RLF) of the MCG; when the RLF of the MCG is detected, determining whether to suspend transmission to the SCG; and when it is determined to suspend transmission to the SCG, starting a connection reestablishment process.

[0012] According to various embodiments of the present disclosure, a user equipment (UE) supporting carrier aggregation (CA) with a primary cell group (MCG) and a secondary cell group (SCG) in a wireless communication system is provided. The UE includes: a transceiver; and at least one processor operably coupled to the transceiver, the processor being configured to: detect a radio link failure (RLF) of the MCG; when the RLF of the MCG is detected, determine whether to suspend transmission to the SCG; and when it is determined to suspend transmission to the SCG, start a connection reestablishment process.

[0013] Before proceeding to the following detailed description, it is helpful to set forth definitions of certain words and phrases used throughout this patent document: the terms "include" and "comprising" and variations thereof refer to inclusion without limitation; the term "or" is inclusive, referring to and / or; the phrases "associated with" and "associated with" and variations thereof may refer to including, being included, interconnected with, containing, being contained within, connected to or connected with, coupled to or coupled with, communicable with, writing with, interleaved, juxtaposed, proximate to, being combined with or combined with, having, having the characteristics of, and the like; and the term "controller" refers to any device, system, or portion thereof that controls at least one operation, such device may be implemented in hardware, firmware, or software, or some combination of at least two thereof. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether locally or remotely.

[0014] In addition, various functions as described below can be implemented or supported by one or more computer programs, each of which is formed by a computer-readable program code and is embodied as a computer-readable medium. The terms "application" and "program" refer to one or more computer programs, software components, instruction sets, processes, functions, objects, categories, examples, related data or parts thereof suitable for the implementation of appropriate computer-readable program codes. The phrase "computer-readable program code" includes any type of computer code, including source code, object code and executable code. The phrase "computer-readable medium" includes any type of medium that can be accessed by a computer, such as a read-only memory (ROM), a random access memory (RAM), a hard drive, a compact disk (CD), a digital video disk (DVD) or any other type of memory. "Non-volatile" computer-readable media excludes wired, wireless, optical or other communication links that transmit instantaneous electrical signals or other signals. Non-transient computer-readable media include media in which data can be permanently stored and media in which data can be stored and rewritten afterwards, such as rewritable optical disks or erasable memory devices.

[0015] Definitions for certain words and phrases are provided throughout this patent document. Those of skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and other aspects, features and advantages of certain embodiments of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0017] Figure 1 illustrates a wireless communication system according to various embodiments;

[0018] Figure 2 illustrates a configuration of a base station in a wireless communication system according to various embodiments;

[0019] Figure 3 illustrates a configuration of a terminal in a wireless communication system according to various embodiments;

[0020] Figure 4 illustrates a configuration of a communication unit in a wireless communication system according to various embodiments;

[0021] Figure 5 A dual connectivity structure illustrating a configuration of a base station and a terminal in a wireless communication system according to various embodiments;

[0022] Figure 6 A flowchart of a terminal when MCG RLF occurs in a wireless communication system according to various embodiments is illustrated;

[0023] Figure 7 FIGURE 1 illustrates a protocol structure of a non-separated SRB1 in a wireless communication system according to various embodiments;

[0024] Figure 8 FIG. 1 illustrates a protocol structure of a split SRB1 in a wireless communication system according to various embodiments;

[0025] Fig. 9 FIG. 1 illustrates a protocol structure of SRB1 in which packet duplication based on carrier aggregation (CA) is configured;

[0026] Fig.10 The diagram shows the protocol structure of non-separated SRB3;

[0027] Fig.11 illustrates an example of a case in which a terminal reports an MCG RLF to a base station when an MCG RLF has occurred according to various embodiments;

[0028] Fig.12 illustrates an example of a case in which a terminal in which an MCG RLF has occurred reports information about the MCGRLF to a base station according to various embodiments;

[0029] Fig.13 illustrates a flow chart of a terminal for determining a radio bearer for sending a failure report message when MCG RLF has occurred according to various embodiments;

[0030] Fig.14 A flow chart illustrating a terminal for sending an MCG RLF report message when an MCG RLF has occurred according to various embodiments;

[0031] Fig.15 illustrates a flow chart for configuring a terminal of a primary path when an MCG RLF has occurred according to various embodiments;

[0032] Fig.16 illustrates a flow diagram of a terminal for configuring a threshold for detaching when an MCG RLF has occurred according to various embodiments;

[0033] Fig.17 illustrates a flow chart for configuring a terminal to detach SRB1 when MCG RLF has occurred according to various embodiments;

[0034] Fig.18 illustrates a protocol structure of a temporary SRB1 that may be used when an MCG RLF occurs according to various embodiments;

[0035] Fig.19 illustrates an example of a case in which a terminal in which MCG RLF has occurred reports a fault report message to a base station according to various embodiments;

[0036] Fig. 20 illustrates a scenario for performing V2X communication between terminals in a wireless communication system according to various embodiments;

[0037] Fig.21 A flow chart illustrating a terminal when a QoS requirement for V2X communication is not met in a wireless communication system according to various embodiments;

[0038] Fig. 22 illustrates an example of a case in which a V2X terminal maps packets to radio bearers in a wireless communication system according to various embodiments;

[0039] Fig.23 illustrates a signal flow between a terminal and a base station when a QoS requirement is not satisfied in V2X communication in a wireless communication system according to various embodiments;

[0040] Fig.24 illustrates a signal flow between a terminal and another terminal when a QoS requirement is not satisfied in V2X communication in a wireless communication system according to various embodiments;

[0041] Fig.25 illustrates a signal flow between terminals when QoS requirements are not met in V2X communication in a wireless communication system according to various embodiments;

[0042] Fig.26 A flow chart illustrating a terminal for sending a packet by monitoring QoS requirements in V2X communication in a wireless communication system according to various embodiments;

[0043] Fig. 27 The figure shows the SRB structure of the base station and the method of notifying the base station of the MCG failure when the MCG failure occurs;

[0044] Fig.28 The figure shows the SRB structure of the base station and the method by which the terminal notifies the base station of the SCG failure when the SCG failure occurs;

[0045] Fig.29 The diagram shows the operation process of the terminal when an MCG failure occurs;

[0046] Fig.30 The diagram shows the operation process of the terminal when an SCG failure occurs;

[0047] Fig.31 The diagram shows the protocol structure for separating SRB1;

[0048] Fig.32 The diagram shows the protocol structure of non-separated SRB3;

[0049] Fig.33 The figure shows the conflict scenario of MCG failure and SCG failure;

[0050] Fig.34 The figure shows another conflict scenario of MCG failure and SCG failure;

[0051] Fig.35 The diagram shows the specific operation process of the terminal when an MCG failure occurs;

[0052] Fig.36 The figure shows the specific operation process of the terminal when an SCG failure occurs;

[0053] Fig.37 The diagram shows the specific operation process of the terminal when an MCG failure occurs;

[0054] Fig.38 The diagram illustrates a method for configuring the MCG fault information message transmission process and the MCG fault report message transmission process;

[0055] Fig.39 illustrates a configuration of a base station in a wireless communication system according to various embodiments; and

[0056] Fig.40 Illustrations illustrate a configuration of a terminal in a wireless communication system according to various embodiments. DETAILED DESCRIPTION

[0057] The following discussion Figures 1 to 40 The various embodiments used to describe the principles of the present disclosure in this patent document may be by way of illustration only and should not be interpreted in any way as limiting the scope of the present disclosure. Those skilled in the art will understand that the principles of the present disclosure can be implemented in any appropriately arranged system or device.

[0058] The terms used in the present disclosure are only used to describe specific embodiments, and are not intended to limit the present disclosure. Singular expressions may include plural expressions unless they are completely different in context. Unless exceptionally limited, all terms used herein, including technical and scientific terms, have the same meaning as the meaning generally understood by those skilled in the art to which the present disclosure belongs. Such terms as defined in commonly used dictionaries may be interpreted as having the meaning of the contextual meaning equivalent to the relevant field of the present technology, and are not interpreted as having an ideal or overly formalized meaning, unless clearly defined in the present disclosure. In some cases, even the terms defined in the present disclosure should not be interpreted as excluding embodiments of the present disclosure.

[0059] Hereinafter, various embodiments of the present disclosure will be described based on a hardware method. However, various embodiments of the present disclosure include techniques using both hardware and software, and therefore various embodiments of the present disclosure may not exclude aspects of software.

[0060] The present disclosure described below relates to an apparatus and method for transmitting status information in a wireless communication system. In particular, the present disclosure describes a technique for transmitting a report message of an MCG RLF and a QoS requirement non-satisfaction report message in a wireless communication system.

[0061] As used below, for the convenience of description, terms referring to signals, terms referring to channels, terms referring to control information, terms referring to network entities, terms referring to elements of devices, etc. are provided by way of example. Therefore, the present disclosure is not limited to the following terms, and other terms having the same technical meanings may be used.

[0062] In addition, the present disclosure uses terms used in certain communication standards (eg, the 3rd Generation Partnership Project (3GPP)) to describe various embodiments, but this is only an example for description. Various embodiments can be easily modified and applied in other communication systems.

[0063] Figure 1 A wireless communication system is illustrated in accordance with various embodiments. Figure 1 The base station 110, the terminal 120, and the terminal 130 are illustrated as some of the nodes using the wireless channel in the wireless communication system. Figure 1 Only one base station is illustrated, but another base station that is the same as or similar to the base station 110 may be further included.

[0064] The base station 110 is a network infrastructure that provides wireless connections to the terminals 120 and 130. The base station 110 has coverage defined as a predetermined geographical area based on the distance at which a signal can be transmitted. In addition to the term "base station", the base station 110 may be referred to as an "access point (AP)", "eNode B (eNB)", "fifth generation node (5G node)", "radio point", "transmission / reception point (TRP)" or another term having an equivalent technical meaning.

[0065] Each of the terminal 120 and the terminal 130 is a device used by a user and communicates with the base station 110 via a wireless channel. In some cases, at least one of the terminal 120 and the terminal 130 may operate without user participation. That is, at least one of the terminal 120 and the terminal 130 may be a device for performing machine type communication (MTC) and may not be carried by a user. In addition to the term "terminal", each of the terminal 120 and the terminal 130 may be referred to as a "user equipment (UE)", "mobile station", "user station", and "remote terminal", "wireless terminal", or "user device" or another term with equivalent technical meaning.

[0066] The base station 110, the terminal 120, and the terminal 130 can transmit and receive radio signals in a millimeter wave (mmWave) frequency band (e.g., 28 GHz, 30 GHz, 38 GHz, or 60 GHz). In this case, in order to improve the channel gain, the base station 110, the terminal 120, and the terminal 130 can perform beamforming. Here, beamforming may include transmit beamforming and receive beamforming. That is, the base station 110, the terminal 120, and the terminal 130 may give directivity to the transmitted signal or the received signal. For this purpose, the base station 110 and the terminals 120 and 130 may select service beams 112, 113, 121, and 131 through a beam search or beam management process. After selecting the service beams 112, 113, 121, and 131, subsequent communications may be performed via resources in a quasi-co-location (QCL) relationship with the resources that transmit the service beams 112, 113, 121, and 131.

[0067] Figure 2 FIG. 1 illustrates a configuration of a base station in a wireless communication system according to various embodiments. Figure 2 The configuration illustrated in may be understood as the configuration of the base station 110. Terms such as "-part" and "-unit" to be used hereinafter mean a unit for processing at least one function or operation, and may be implemented by hardware, software, or a combination of hardware and software.

[0068] refer to Figure 2 , the base station includes a wireless communication unit 210, a backhaul communication unit 220, a storage device 230 and a controller 240.

[0069] The wireless communication unit 210 may perform a function for transmitting / receiving a signal via a wireless channel. For example, the wireless communication unit 210 may perform a conversion function between a baseband signal and a bit stream according to the physical layer specification of the system. For example, during data transmission, the wireless communication unit 210 may generate complex symbols by encoding and modulating the transmitted bit stream. In addition, during data reception, the wireless communication unit 210 may recover the received bit stream by demodulating and decoding the baseband signal.

[0070] In addition, the wireless communication unit 210 up-converts the baseband signal to a radio frequency (RF) band signal and then transmits the RF band signal via an antenna. In addition, the wireless communication unit 210 down-converts the RF band signal received via the antenna to a baseband signal. For this purpose, the wireless communication unit 210 may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a digital-to-analog converter (DAC), an analog-to-digital converter (ADC), etc. In addition, the wireless communication unit 210 may include a plurality of transmission / reception paths. In addition, the wireless communication unit 210 may include at least one antenna array consisting of a plurality of antenna elements.

[0071] In terms of hardware, the wireless communication unit 210 may be composed of a digital unit and an analog unit, and the analog unit may include multiple subunits depending on operating power, operating frequency, etc. The digital unit may be implemented with at least one processor (eg, a digital signal processor (DSP)).

[0072] As described above, the wireless communication unit 210 transmits / receives signals. Therefore, all or part of the wireless communication unit 210 may be referred to as a "transmitter", "receiver" or "transceiver". In the following description, transmission and reception performed via a wireless channel are used in a meaning including a case where the above-mentioned processing is performed by the wireless communication unit 210.

[0073] The backhaul communication unit 220 provides an interface for communicating with other nodes in the network. That is, the backhaul communication unit 220 converts a bit stream sent from the base station to another node, such as another access node, another base station, an upper node, a core network, etc., into a physical signal, and converts a physical signal received from another node into a bit stream.

[0074] The storage device 230 stores data such as basic programs, applications, and setting information for the operation of the base station. The storage device 230 may be configured as a volatile memory, a nonvolatile memory, or a combination of a volatile memory and a nonvolatile memory. In addition, the storage device 230 may provide the data stored therein in response to a request from the controller 240.

[0075] The controller 240 controls the overall operation of the base station. For example, the controller 240 sends and receives signals via the wireless communication unit 210 or via the backhaul communication unit 220. In addition, the controller 240 records and reads data in the storage device 230. The controller 240 may perform the functions of the protocol stack required by the communication standard. According to another embodiment, the protocol stack may be included in the wireless communication unit 210. For this purpose, the controller 240 may include at least one processor.

[0076] According to various embodiments, the controller 240 may receive the state information and may control an operation for processing the received information. For example, the controller 240 may control the base station to perform operations according to various embodiments to be described later.

[0077] Figure 3 Illustrations illustrate a configuration of a terminal in a wireless communication system according to various embodiments. Figure 3 The configuration illustrated in may be understood as the configuration of the terminal 120. Terms such as "-part" and "-unit" to be used hereinafter mean a unit for processing at least one function or operation, and may be implemented by hardware, software, or a combination of hardware and software.

[0078] refer to Figure 3 , the terminal includes a communication unit 310, a storage device 320 and a controller 330.

[0079] The communication unit 310 can perform a function for transmitting / receiving a signal via a wireless channel. For example, the communication unit 310 can perform a conversion function between a baseband signal and a bit stream according to the physical layer specification of the system. For example, during data transmission, the communication unit 310 can generate complex symbols by encoding and modulating the transmission bit stream. In addition, during data reception, the communication unit 310 can recover the received bit stream by demodulation and decoding of the baseband signal. In addition, the communication unit 310 up-converts the baseband signal to a radio frequency (RF) band signal and then transmits the RF band signal via an antenna. In addition, the communication unit 310 down-converts the RF band signal received via the antenna to a baseband signal. For example, the communication unit 310 may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator DAC, an ADC, etc.

[0080] In addition, the communication unit 310 may include multiple transmit / receive paths. In addition, the communication unit 310 may include at least one antenna array consisting of multiple antenna elements. In terms of hardware, the communication unit 310 may be configured as a digital circuit and an analog circuit (e.g., a radio frequency integrated circuit (RFIC)). Here, the digital circuit and the analog circuit may be implemented as a single package. In addition, the communication unit 310 may include multiple RF chains. In addition, the communication unit 310 may perform beamforming.

[0081] The communication unit 310 transmits / receives signals as described above. Therefore, all or part of the communication unit 310 may be referred to as a "transmitter", "receiver" or "transceiver". In the following description, transmission and reception performed via a wireless channel are used to include the meaning of a case where the processing described above is performed by the communication unit 310.

[0082] The storage device 320 stores data such as basic programs, applications, and setting information for the operation of the terminal. The storage device 320 can be configured as a volatile memory, a non-volatile memory, or a combination of a volatile memory and a non-volatile memory. In addition, the storage device 320 can provide the data stored therein in response to a request from the controller 330.

[0083] The controller 330 controls the overall operation of the terminal. For example, the controller 330 can send and receive signals via the communication unit 310. In addition, the controller 330 records and reads data in the storage device 320. The controller 330 can perform the functions of the protocol stack required by the communication standard. To this end, the controller 330 may include at least one processor or microprocessor, or may be a part of a processor. In addition, a part of the communication unit 310 and the controller 330 may be referred to as a communication processor (CP).

[0084] According to various embodiments, the controller 330 may transmit state information or receive state information and may control an operation for processing the received information. For example, the controller 330 may control the terminal to perform operations according to various embodiments to be described later.

[0085] Figure 4 The diagram illustrates a configuration of a communication unit in a wireless communication system according to various embodiments. Figure 4 Graphics Figure 2 The wireless communication unit 210 or Figure 3 An example of a specific configuration of the communication unit 310. In particular, Figure 4 Components for performing beamforming are illustrated as Figure 2 The wireless communication unit 210 or Figure 3 Part of the communication unit 310.

[0086] refer to Figure 4 , the wireless communication unit 210 or the communication unit 310 includes a coding and modulation unit 402, a digital beamforming unit 404, a plurality of transmission paths 406-1 to 406-N, and an analog beamforming unit 408.

[0087] The coding and modulation unit 402 performs channel coding. For channel coding, at least one of a low density parity check (LDPC) code, a convolutional code, and a polar code may be used. The coding and modulation unit 402 generates modulation symbols by performing constellation mapping.

[0088] The digital beamforming unit 404 performs beamforming on a digital signal (e.g., a modulation symbol). For this purpose, the digital beamforming unit 404 multiplies the modulation symbol by a beamforming weight. Here, the beamforming weight is used to change the amplitude and phase of the signal, and may be referred to as a "precoding matrix", "precoder", etc. The digital beamforming unit 404 outputs the digital beamformed modulation symbol to a plurality of transmission paths 406-1 to 406-N. In this case, according to a multiple-input multiple-output (MIMO) transmission scheme, the modulation symbol may be multiplexed, or the same modulation symbol may be provided to a plurality of transmission paths 406-1 to 406-N.

[0089] A plurality of transmission paths 406-1 to 406-N converts the digital signal of digital beamforming into an analog signal. For this purpose, each of the plurality of transmission paths 406-1 to 406-N may include an inverse fast Fourier transform (IFFT) calculator, a cyclic prefix (CP) inserter, a DAC, and an up-converter. The CP inserter is for an orthogonal frequency division multiplexing (OFDM) scheme and can be excluded when another physical layer scheme (e.g., filter bank multi-carrier (FBMC)) is applied. That is, a plurality of transmission paths 406-1 to 406-N0 provide independent signal processing processes for a plurality of streams generated by digital beamforming. However, depending on the implementation scheme, some of the components of the plurality of transmission paths 406-1 to 406-N may be used in common.

[0090] The analog beamforming unit 408 performs beamforming on the analog signal. For this purpose, the digital beamforming unit 404 multiplies the analog signal by a beamforming weight. Here, the beamforming weight is used to change the amplitude and phase of the signal. In particular, the analog beamforming unit 408 can be variously configured depending on the connection structure between the multiple transmission paths 406-1 to 406-N and the antenna. For example, each of the multiple transmission paths 406-1 to 406-N can be connected to an antenna array. As another example, the multiple transmission paths 406-1 to 406-N can be connected to an antenna array. As another example, the multiple transmission paths 406-1 to 406-N can be adaptively connected to an antenna array or can be connected to two or more antenna arrays.

[0091] Figure 5 A dual connectivity structure of a base station and a terminal in a wireless communication system according to various embodiments is illustrated.

[0092] refer to Figure 5In the dual connectivity structure, two base station nodes 510 and 520 may perform the functions of a base station (e.g., base station 110), and the base station nodes 510 and 520 may be connected to each other via an X2 interface and / or an Xn interface. In various embodiments, the base station node 510 that is primarily connected to the terminal 530 (e.g., the terminal 120 or the terminal 130) may be referred to as a master node (MN), and the base station node that is secondary connected to the dual connectivity structure may be referred to as a secondary node (SN). MN 510 may be an anchor point for signaling radio bearer 1 (SRB1) and SRB2, SRB1 may indicate a radio resource control (RRC) configuration of the terminal 530, and SRB2 may send a non-access stratum NAS message for configuring a connection between the terminal 530 and the core network. Each node can be connected to the terminal 530 via one or more cells to communicate with the terminal 530, and the one or more cells may include a primary cell (PCell) 511 that must be connected to the primary node, a primary secondary cell (PSCell) 521 that must be connected to the secondary node, and at least one of the secondary cells (SCell) 513, 515, 523 and 525 that can be selectively used by each node. In various embodiments, the cell managed by the primary node may be included in the primary cell group (MCG), and the cell managed by the secondary node may be included in the secondary cell group (SCG). The terminal 530 may also communicate with the base station node 510 and / or the base station node 520 via at least one of the PCell 531, the PSCell 537 and / or the additional SCells 533, 535, 539 and 541. In this case, the PCell 531, PSCell 537, and SCells 533, 535, 539, and 541 may be resources that are not physically different from but correspond to the PCell 511, PSCell 521, and SCells 513, 515, 523, and 525 having the same frequency band, respectively. Therefore, the primary cell group and the secondary cell group may be configured identically in the connection process between the base station and the terminal.

[0093] In this dual connection structure, when the radio link condition of the secondary cell group is not good, and thus a radio link failure (RLF) (i.e., SCG RLF) of the secondary cell group occurs, the terminal 530 can send an SCG failure information message to the main node (e.g., base station node 510) via the main cell group. The SCG failure information message can be sent to SRB1, and the base station receiving the message can indicate reconfiguration or release of the secondary cell group in which the SCG RLF has occurred. In this case, because the SCG RLF is a problem with the secondary cell group and may not affect the transmission performed via the main cell group, the data sent to the main cell group can be continuously sent without interruption. This is because the SCG RLF is only a problem with the secondary cell group and may not affect the transmission performed in the main cell group. In addition, an SCG failure information message can be sent when the reconfiguration of the SCG failure occurs. In general, SCGRLF and reconfiguration failures can be collectively referred to as SCG failures.

[0094] On the contrary, when the RLF (i.e., MCGRLF) of the primary cell group occurs because the radio link status of the primary cell group is not good, the terminal 530 may not be able to send MCG failure information via the primary cell group because the radio link status of the primary cell group is not good. In this case, the terminal 530 and / or the base station node 510 may need to reconfigure the primary cell group by performing an RRC connection reconstruction process. In the RRC connection reconstruction process, operations related to the RRC connection reconstruction process are performed depending on the radio link status of the primary cell group, regardless of the connection status of the secondary cell group. Therefore, an interruption in which the transmission of data sent to the secondary cell group and data sent to the primary cell group is interrupted may occur. However, when the secondary cell group is available, the interruption of the data transmission of the secondary cell group may not necessarily be required. When the terminal 530 is able to send a report of the MCG RLF to the secondary cell group, the interruption caused by the RRC connection reconstruction can be prevented, and the interruption of the data transmission of the secondary cell group can also be prevented. In addition, the RRC connection reconstruction operation can be performed when the RRC reconfiguration accompanying handover or synchronization fails, in which case a method similar to the MCG RLF report can be used. In general, this can be collectively referred to as an MCG failure.

[0095] Figure 6 A flowchart of a terminal is illustrated when MCG RLF occurs in a wireless communication system according to various embodiments. Figure 6 A method 600 of operating a terminal 530 is illustrated.

[0096] refer to Figure 6In step 601, the terminal may detect a triggering of an RLF for the MCG. In other words, the terminal may detect that the MCG RLF has been triggered. For example, the terminal may detect that the MCG RLF has been triggered for reasons such as expiration of a T310 timer, a random access failure, and / or reaching a maximum number of retransmissions of the RLC.

[0097] In step 603, the terminal may stop transmission of SRBs and / or data radio bearers (DRBs) sent to the MCG. Since the terminal cannot properly perform data transmission to the primary cell group in the MCG RLF case, the terminal may suspend transmission of all SRBs and / or DRBs sent to the primary cell group.

[0098] In step 605, the terminal may reconfigure (or reset) the MCG media access control (MAC). Since the terminal cannot use the MAC of the primary cell group when the MCG RLF is triggered, the terminal may reset the MAC of the primary cell group.

[0099] In step 607, the terminal may stop a timer (e.g., T304 timer). For example, when the T304 timer is running or another timer is running for handover, the terminal may stop the timer because the operation of the corresponding timer is no longer needed. When there is no running timer, step 607 may be omitted.

[0100] At operation 609, the terminal may trigger an MCG fault report. For example, the terminal may trigger an MCG fault report to notify the base station that an MCG RLF has occurred. In various embodiments, the notification may be indicated via a secondary cell group. The radio bearer for the MCG RLF report may include at least one of a separate SRB1 or SRB3, the separate SRB1 may be used for transmission to the secondary cell group, and the SRB3 may be used for direct transmission to the secondary node.

[0101] Figure 7 A protocol structure of a non-separated SRB1 in a wireless communication system according to various embodiments is illustrated.

[0102] refer to Figure 7, the non-separated SRB1 710 can be configured to send RRC messages, and can be associated with RRC 720, Packet Data Convergence Protocol (PDCP) 730, Radio Link Control (RLC) 740, Medium Access Control (MAC) 750, and Physical Layer (PHY) 760 from above. In various embodiments, the term "non-separated" may refer to the presence of one RLC entity (e.g., RLC 740) for the corresponding radio bearer. In various embodiments, the RLC entity may be used interchangeably with the RLC bearer or logical channel. The cell group for the non-separated SRB1 710 may be a primary cell group 770. In addition, the RRC of SRB1 may be associated with a master node, and the master node may manage the RRC connection of the terminal.

[0103] Figure 8 A protocol structure of a split SRB1 in a wireless communication system according to various embodiments is illustrated.

[0104] refer to Figure 8 , the split SRB1 810 may be configured to send an RRC message, and may be associated with a layer of RRC 821, a layer of PDCP 823, two or more layers of RLC 825 and 831, two or more layers of MAC 827 and 833, and two or more layers of PHY 829 and 835 from the top. In various embodiments, the term "split" may refer to the presence of two or more RLC entities (e.g., RLC 825 and 831) for the corresponding radio bearer. The cell group for the split SRB1 may include a primary cell group 840 and a secondary cell group 850. In addition, the RRC of the split SRB1 may be associated with a master node, and the master node may manage the RRC connection of the terminal. The RLC entities 825 and 831 of the split SRB1 may include a primary RLC (or primary path) entity used regardless of the amount of data to be sent, and a secondary RLC (or secondary path) entity used when the data to be sent is equal to or greater than a threshold (e.g., ul-DataSplitThreshold). For example, the base station may notify the terminal of the threshold ul-DataSplitThreshold through RRC configuration. In addition, in the corresponding split SRB1, packet duplication may be performed to duplicate packets in the PDCP entity of the transmitter and send all data to multiple RLC entities. When packet duplication transmission is activated, multiple RLC entities may be used for packet transmission at the same time.

[0105] Fig. 9 The protocol structure of SRB1 in which carrier aggregation (CA)-based packet duplication is configured is illustrated.

[0106] The separate SRB1 910 in which CA-based replication is configured may be configured to transmit an RRC message and may be associated with one layer of RRC 911, one layer of PDCP 913, two or more layers of RLC 915 and 921, two or more layers of MAC 917 and 923, and two or more layers of PHY 919 and 925 from above. In the SRB1 in which CA-based packet replication is configured, packet replication for replicating packets in the PDCP entity of the transmitter and transmitting all data to multiple RLC entities may be performed. When packet replication transmission is activated, multiple RLC entities may be used for packet transmission at the same time. When CA-based packet replication is configured, there may be two or more RLC entities (e.g., RLC 915 and 921) for corresponding radio bearers configured in the same cell group. All cell groups for the SRB1 in which CA-based packet replication is configured may be primary cell groups 930 and 940. However, a list of cells available for each RLC entity (logical channel) may be configured differently. For example, in order to prevent the packets generated in each RLC entity from being sent simultaneously, the list of cells that can be used by each RLC entity (logical channel) can be configured differently. In various embodiments, the list of cells that can be used by each RLC entity (logical channel) can be referred to as "Allowed Serving Cell", and the Allowed Serving Cell can be configured for each RLC entity and / or each logical channel. The RRC in which the terminal separation SRB1 based on CA packet replication is configured can be associated with a master node, and the master node can manage the RRC connection of the terminal. In various embodiments, the RLC entities 915 and 921 in which the SRB1 based on CA packet replication is configured can include a primary RLC used regardless of whether the packet replication is activated, and a secondary RLC entity used when the packet replication is activated. The base station can notify the terminal of the configuration of the primary RLC and the secondary RLC through the RRC configuration.

[0107] Fig.10 The diagram shows the protocol structure of non-separated SRB3.

[0108] refer to Fig.10, the non-separated SRB3 1010 can be configured to send RRC messages and can be associated with the layers of RRC1021, PDCP 1023, RLC 1025, MAC 1027 and PHY 1029 from above. In various embodiments, the term "non-separated" can refer to the presence of one RLC entity for the corresponding radio bearer. In various embodiments, the RLC entity can be used interchangeably with the RLC bearer or logical channel. The cell group for the non-separated SRB3 1010 can be a secondary cell group 1030. In addition, the RRC of SRB3 1010 can be associated with a secondary node, and the secondary node can manage certain RRC connections of the terminal.

[0109] Fig.11 An example of a case in which a terminal reports an MCG RLF to a base station when an MCG RLF occurs according to various embodiments is illustrated.

[0110] refer to Fig.11 , when SRB3 is configured in a case where it is necessary for the terminal 1130 (e.g., the terminal 530) to forward information indicating that MCG RLF has occurred (or information indicating that MCG RLF has been triggered, MCG RLF report, MCG fault information, or MCG RLF information) to the base station because MCG RLF has occurred, the terminal 1130 may forward the MCG RLF information to the secondary node 1120 (e.g., the base station node 520) via SRB3. In various embodiments, a fault report message may be defined, and the fault report message may include at least one of information indicating that MCG RLF has occurred, a reason why MCG RLF has occurred, or measurement report information. When the terminal 1130 notifies the base station via SRB3 that MCG RLF has occurred, the cell group used may be a secondary cell group. However, because the anchor node of SRB3 is the secondary node 1120, the secondary node 1120 may be required to resend the MCG RLF information to the primary node 1110 (e.g., the base station node 510) that manages the MCG connection. In an embodiment, the content of the fault report message sent to SRB3 can be forwarded as is from the secondary node 1120 to the primary node 1110. In another embodiment, the secondary node 1120 can use another message to process information about the terminal where the MCG RLF has occurred and the cause of the occurrence of the MCG RLF, and can send the processed information to the primary node 1110.

[0111] Fig.12 An example of a case in which a terminal in which an MCG RLF has occurred reports information about the MCGRLF to a base station according to various embodiments is illustrated.

[0112] refer to Fig.12, when SRB1 is configured or can be configured in a case where the terminal 1230 (e.g., the terminal 530) needs to forward information indicating that MCG RLF has occurred (or information indicating that MCG RLF has been triggered, MCG RLF report, MCG fault information, or MCG RLF information) to the base station because MCG RLF has occurred, the terminal 1230 may forward the MCG RLF information to the secondary node 1220 (e.g., the base station node 520) via SRB1, in which the terminal 1230 (e.g., the terminal 530) needs to forward information indicating that MCG RLF has occurred (or information indicating that MCG RLF has been triggered, MCG RLF report, MCG fault information, or MCG RLF information) to the base station because MCG RLF has occurred. In various embodiments, a fault report message may be defined, and the fault report message may include at least one of an indication indicating that MCG RLF has occurred, a reason why MCG RLF has occurred, or measurement report information. When the terminal 1230 notifies the base station via SRB3 that MCGRLF has occurred, since the primary cell group cannot be used, the cell group used may become the secondary cell group. In the case of separating SRB1, since the anchor node becomes the primary node 1210 (e.g., the base station node 510), the fault report message is not directly forwarded to the secondary node. In other words, by referring to Figure 8 With the described structure of the separated SRB1, a packet transmitted to the secondary cell group may be transmitted from the RLC entity connected to the secondary cell group to the PDCP entity, and may then be forwarded to the RRC entity of the primary node.

[0113] Fig.13 is a flow chart of a terminal for determining a radio bearer for sending a failure report message when MCG RLF has occurred according to various embodiments. Fig.13 The operation method of the terminal 530 is illustrated.

[0114] refer to Fig.13 In step 1301, the terminal may detect the triggering of the RLF for the MCG. In other words, the terminal may detect that the MCG RLF has been triggered.

[0115] In step 1303, the terminal may determine whether SRB3 is configured. When the terminal needs to send a fault report message to the secondary cell group due to the occurrence of MCG RLF, the terminal may determine which radio bearer to use based on whether SRB3 is configured. When SRB3 is configured (Yes in step 1303), the terminal may perform step 1305. In contrast, when SRB3 is not configured (No in step 1303), the terminal may perform step 1307.

[0116] In step 1305, the terminal may send an MCG RLF report message (or a fault report message) to the base station via the configured SRB3. Fig.11As described above, the base station (eg, the secondary node 1120) that receives the fault report message may forward the fault report message to the primary node (eg, the primary node 1110) again.

[0117] In step 1307, the terminal may send an MCG RLF report message (or a fault report message) to the base station via the detached SRB1. When the terminal is capable of configuring the detached SRB1 even if the detached SRB1 is not configured, the terminal may generate a message for detaching the SRB1 and may send the message for detaching the SRB1 to the base station (e.g., the base station node 520) via the secondary cell group.

[0118] Fig.14 is a flowchart of a terminal for sending an MCG RLF report message when an MCG RLF has occurred according to various embodiments. Fig.14 A method of operating the terminal 120 is exemplified.

[0119] refer to Fig.14 In step 1401, the terminal may detect the triggering of the RLF for the MCG. In other words, the terminal may detect that the MCG RLF has been triggered. For example, the terminal may send a fault report message to the secondary cell group only when the separation SRB1 is configured. In this case, the terminal may determine to perform the RRC connection reestablishment procedure depending on whether the separation SRB1 is configured.

[0120] In step 1403, the terminal may determine whether SRB1 is configured or whether packet replication is configured for SRB1. When SRB1 is configured or packet replication is configured for SRB1 ("Yes" in step 1403), the terminal may perform step 1405. In contrast, when SRB1 is not configured or packet replication is not configured for SRB1, the terminal may perform step 1407.

[0121] In step 1405, the terminal may send an MCG RLF report message (or a fault report message) to SRB 1. For example, the terminal may send the MCG RLF report message to a separate SRB 1 or an SRB 1 in which packet replication has been configured. For this purpose, packet replication transmission may be activated.

[0122] In step 1407, the terminal may perform an RRC connection reestablishment procedure. For example, the terminal may perform an RRC connection reestablishment procedure to configure an RRC connection including a configuration of SRB1 and / or detaching SRB1.

[0123] Fig.15 A flow chart is illustrated for configuring a terminal of a primary path when an MCG RLF has occurred according to various embodiments. Fig.15 A method of operating the terminal 120 is exemplified.

[0124] refer to Fig.15 In step 1501, the terminal may detect the triggering of the RLF for the MCG. In other words, the terminal may detect that the MCG RLF has been triggered.

[0125] In step 1503, the terminal may send an MCG RLF report message (or a fault report message) to the separated SRB 1. For example, when the separated SRB 1 is configured, when the packet copy transmission of the SRB 1 is configured, and / or when the separated SRB 1 can be configured, the terminal may send the MCG RLF report message to the separated SRB 1.

[0126] In step 1505, the terminal may configure the main path as an RLC entity (logical channel) connected to the SCG. In a case where a separation SRB1 is used, the main RLC entity of the separation SRB1 is an RLC entity connected to the primary cell group and the threshold ul-DataSplitThreshold for separation is not 0, the terminal may not be able to send a fault report message to the secondary cell group. For this purpose, the terminal may change the main RLC entity to an RLC entity (logical channel) connected to the secondary cell group. Therefore, the terminal can send data to the RLC entity connected to the secondary logical channel. In various embodiments, the order of performing steps 1503 and 1505 may be changed.

[0127] Fig.16 A flow chart of a terminal for configuring a threshold for detaching when MCG RLF has occurred according to various embodiments is illustrated. Fig.16 A method of operating the terminal 530 is illustrated.

[0128] refer to Fig.16 In step 1601, the terminal may detect the triggering of the RLF for the MCG. In other words, the terminal may detect that the MCG RLF has been triggered.

[0129] In step 1603, the terminal may send an MCG RLF report message (or a fault report message) to the separated SRB 1. For example, when the separated SRB 1 is configured, when the packet copy transmission of the SRB 1 is configured, and / or when the separated SRB 1 can be configured, the terminal may send the MCG RLF report message to the separated SRB 1.

[0130] In step 1605, the terminal may set the threshold ul-DataSplitThreshold for separation to 0. In the case where the separation SRB1 is used, the primary RLC entity of the separation SRB1 is an RLC entity connected to the primary cell group, and the threshold ul-DataSplitThreshold for separation is not 0, the terminal may not be able to send a fault report message to the secondary cell group. For this purpose, the terminal may set the threshold ul-DataSplitThreshold for separation to 0. In various embodiments, the threshold ul-DataSplitThreshold may be temporarily set to zero, or a state in which the threshold ul-DataSplitThreshold is set to zero may be continuously maintained.

[0131] In various embodiments, the terminal may send an MCG RLF report message to an RLC entity connected to a secondary cell group regardless of a threshold value for separation or a primary RLC entity. In addition, the terminal may send all SRB1 messages occurring in the MCG RLF case to an RLC entity connected to a secondary cell group regardless of a threshold value for separation or a primary RLC entity. As another example, the terminal may activate packet copy transmission and may cause SRB1 messages to be sent to all RLC entities. The terminal may send data to an RLC entity connected to a secondary logical channel using at least one of the above methods. In various embodiments, the order of performing steps 1603 and 1605 may be changed.

[0132] Fig.17 illustrates a flow chart for configuring a terminal to detach SRB1 when MCG RLF has occurred according to various embodiments; Fig.17 A method of operating the terminal 530 is illustrated.

[0133] refer to Fig.17 In step 1701, the terminal may detect the triggering of RLF for MCG. In other words, the terminal may detect that MCG RLF has been triggered.

[0134] In step 1703, the terminal may send an MCG RLF report message (or a fault report message) to the cell of the SCG. For example, the terminal may send an MCG RLF report message to the separation SRB1. However, when the separation SRB1 is not configured, it is impossible to send the MCG RLF report message. Therefore, the terminal may activate the RLC entity connected to the secondary cell group to configure the separation SRB1. For this purpose, when the terminal sets the logical channel identifier (ID) in the RLC entity connected to the secondary cell group to a specific value and sends the MCG RLF report message to the secondary cell group, the base station (e.g., base station node 520) receiving the MCG RLF report message may identify that the separation SRB1 has been generated by receiving the corresponding logical channel ID. In various embodiments, the logical channel ID having a specific value may be value 1, which is the logical channel ID for SRB1. In addition, the terminal may activate the receiving RLC entity to receive downlink data sent to the separation SRB1.

[0135] In step 1705, the terminal may apply the basic configuration of the Split SRB1. For example, in the case where there is no applicable setting value of the Split SRB1 when the Split SRB1 is generated, the terminal may apply the default value of the Split SRB1. In various embodiments, the order of performing steps 1703 and 1705 may be changed.

[0136] Fig.18 FIG. 1 illustrates a protocol structure of a temporary SRB1 that may be used when an MCG RLF occurs according to various embodiments.

[0137] When MCG RLF has occurred for the terminal, the detached SRB1 can be used to send an MCG RLF report message (or a fault report message) including information indicating that MCGRLF has occurred. However, because it is in the MCG RLF state, it is impossible to use the RLC entity connected to the primary cell group among the RLC entities of the detached SRB1 and the protocol stack thereafter. Therefore, in this case, other types of SRB1 (or temporary SRB1) structures can be temporarily used.

[0138] refer to Fig.18 , temporary SRB1 1810 can be configured to send RRC messages and can be associated with layers of RRC1821, PDCP 1823, RLC 1825, MAC 1827, and PHY 1829 starting from the top. Because there is only one RLC entity in temporary SRB1 1810, temporary SRB1 1810 can follow the operation of non-separated radio bearers. The cell group for temporary SRB11810 can be secondary group 1830. In addition, the RRC of temporary SRB1 1810 can be associated with the master node, and the master node can manage the RRC connection of the terminal. In other words, in Fig.18 In the embodiment, when MCG RLF has occurred, the terminal notifies the base station that MCG RLF has occurred using temporary SRB1 1810 based on the radio bearer structure of the structure of temporary SRB1 1810 as described above.

[0139] Fig.19 An example of a case in which a terminal in which MCG RLF has occurred reports a fault report message to a base station according to various embodiments is illustrated.

[0140] refer to Fig.19 , when the MCG RLF report message needs to be forwarded to the base station due to the occurrence of MCG RLF, the terminal 1930 (e.g., the terminal 530) may forward the MCG RLF report message to the secondary node 1920 (e.g., the base station node 520) using the MAC control element (CE) of the secondary cell group. In various embodiments, a new MAC CE for forwarding the MCG RLF report message may be defined, and the MCG RLF report message may include at least one of information indicating that the MCG RLF has occurred, a reason why the MCG RLF has occurred, or measurement report information. Because the cell group to which the MCG RLF report message is sent is the secondary cell group, the base station that receives the MCG RLF report message via the MAC CE may be the secondary node 1920 or a distributed unit (DU) connected to the secondary node 1920. Therefore, for the secondary node 1920 or the DU connected to the secondary node 1920, it may be necessary to send the MCGRLF report message to the primary node 1910 (e.g., the base station node 510) that manages the MCG connection or the central unit (CU) of the primary node 1910. In various embodiments, the content of the MCG RLF report message sent to the MAC CE may be forwarded as is from the secondary node 1920 to the primary node 1910. In another embodiment, the secondary node 1920 may reprocess the information about the terminal where the MCG RLF has occurred and the cause of the MCG RLF using another message, and may send the reprocessed information to the primary node 1910.

[0141] Fig. 20 A scenario for performing V2X communication between terminals in a wireless communication system according to various embodiments is illustrated.

[0142] refer to Fig. 20 In V2X communication, the V2X terminal 2020 (for example, the terminal 120), the V2X terminal 2030 (for example, the terminal 130), and the V2X terminal 2040 may directly perform communication with each other without communicating with the base station 110. In various embodiments, the scheme of V2X communication (or V2X communication scheme) may be one of the following schemes:

[0143] -Unicast scheme: a scheme in which one transmitting terminal communicates with one receiving terminal

[0144] -Multicast scheme: A scheme in which one transmitting terminal communicates with multiple specific receiving terminals

[0145] -Broadcast scheme: A scheme in which one transmitting terminal communicates with multiple unspecified receiving terminals

[0146] Which of the above schemes will be used may be determined based on the nature of the traffic to be sent and / or the nature of the V2X terminals participating in the communication. In various embodiments, the base station may determine the V2X communication scheme and may forward the determined V2X communication scheme to the terminal through RRC configuration.

[0147] In various embodiments, in order to support V2X communication regardless of the V2X communication scheme, the transmitting V2X terminal 2020 may transmit data for V2X communication to one or more V2X terminals 2030 and 2040. According to an embodiment, the data transmitted by the transmitting V2X terminal 2020 may be received only by a terminal that is allowed to receive the data transmitted by the transmitting V2X terminal 2020. In various embodiments, when V2X communication is performed within the coverage of the base station 2010, the base station 2010 may control the V2X communication. In this case, the base station 2010 may perform at least one function among RRC connection configuration, radio resource (frequency and time resource) allocation, transmission scheme configuration, radio bearer configuration, and quality of service (QoS).

[0148] Fig.21 A flow chart illustrating a terminal when a QoS requirement for V2X communication is not satisfied in a wireless communication system according to various embodiments. Fig.21 A method of operating the V2X terminal 2020, 2030 or 2040 is illustrated.

[0149] refer to Fig.21 In step 2101, the terminal may determine that the QoS requirement of a specific packet or DRB cannot be met. In V2X communication, because the V2X terminal performs direct data communication with another V2X terminal instead of with the base station, it may be difficult for the base station to determine whether the transmitted service meets the QoS requirement. Therefore, it may be necessary to check whether the QoS requirement of the V2X terminal participating in the data communication is met. For example, Fig. 20At least one of the transmitting V2X terminal 2020 or the receiving V2X terminals 2030 and 2040 participating in the V2X communication shown may determine whether the QoS requirements of the processed data are met. According to an embodiment, the V2X terminal may monitor whether a specific packet or data processed in a specific DRB meets the QoS requirements. For example, the V2X terminal may monitor the packets scheduled for a predetermined time to determine whether a separate packet or a packet of the same type meets the QoS requirements of the corresponding packet. In various embodiments, the QoS requirements may include at least one of waiting time, reliability, data rate, or loss rate. For example, the QoS requirements of a packet may be mapped to the V2X QoS ID (VQI) of the packet. Therefore, the packet sent by the V2X terminal may have a VQI value corresponding to it, and there may be a QoS requirement corresponding to the VQI. According to an embodiment, the V2X terminal may monitor whether the packet of the same VQI can meet the QoS requirements at a predetermined time. In various embodiments, the predetermined time may be pre-configured or configured by the base station.

[0150] In step 2103, the terminal may send information indicating that the QoS requirement cannot be met to the base station and / or another terminal. In other words, when the QoS requirement cannot be met, the pre-configured V2X terminal (transmitting V2X terminal and / or receiving V2X terminal) may indicate to the base station or another V2X terminal that the QoS requirement cannot be met. In various embodiments, the information indicating that the QoS requirement cannot be met may include at least one of the ID of the radio bearer that does not meet the QoS requirement, the QoS flow ID (QFI), the type of the unsatisfied QoS requirement, or the degree of unsatisfaction of the unsatisfied QoS requirement. According to various embodiments, the transmitting V2X terminal may send information indicating that the QoS requirement of the terminal cannot be met to a neighbor terminal based on a broadcast scheme.

[0151] In step 2105, the terminal may reconfigure or release the bearer. For example, a V2X terminal capable of configuring a base station or a radio bearer may perform an RRC connection reconfiguration including a radio bearer that does not meet QoS requirements. The RRC connection reconfiguration may include at least one of reconfiguration or release of a radio bearer.

[0152] Fig. 22 An example of a case in which a V2X terminal maps a packet to a radio bearer in a wireless communication system according to various embodiments is illustrated.

[0153] refer to Fig. 22, when a packet 2220 is generated in an upper layer such as an application layer of a V2X terminal 2210 (e.g., the V2X terminal 2020, 2030, or 2040) and forwarded to layer 2 (e.g., service data application protocol (SDAP)) of the V2X terminal 2210, the V2X terminal 2210 may determine what kind of packet the packet 2220 is. For example, the V2X terminal 2210 may determine what kind of packet the packet 2220 is by interpreting data of the V2X terminal 2210, and the V2X terminal 2210 may identify a QoS requirement of the packet 2220. Through the QoS requirement, the V2X terminal 2210 may configure a VQI corresponding to the packet 2220. When the QoS requirement or the VQI is configured for the packet 2220, the V2X terminal 2210 may determine to which radio bearer the packet 2220 is to be transmitted. For example, the radio bearer to which the packet 2220 is to be transmitted may be determined by the radio bearer and the logical channel configured by the base station, or may be determined as a radio bearer required for the V2X terminal 2210 to meet the QoS requirement. The packet 2220 may be transmitted to the determined radio bearer.

[0154] Fig.23 Illustration of a signal flow between a terminal and a base station when QoS requirements are not met in V2X communication in a wireless communication system according to various embodiments.

[0155] refer to Fig.23 In step 2301, the V2X terminal 2310 (e.g., the V2X terminal 2020, 2030, or 2040) may determine that the QoS requirement cannot be met. In V2X communication, because the V2X terminal 2310 performs data communication directly with another V2X terminal rather than with the base station 2320 (e.g., the base station 2010), it may be difficult for the base station 2320 to determine whether the transmitted service meets the QoS requirement. Therefore, the V2X terminal 2310 participating in the data communication may need to check whether the QoS requirement is met. For example, Fig. 20At least one of the transmitting V2X terminal 2020 or the receiving V2X terminals 2030 and 2040 participating in the V2X communication shown may determine whether the QoS requirements of the processed data are met. According to an embodiment, the V2X terminal 2310 may monitor whether a specific packet or data processed in a specific DRB meets the QoS requirements. For example, the V2X terminal 2310 may monitor the packets scheduled for a predetermined time, thereby determining whether a separate packet or a packet of the same type meets the QoS requirements of the corresponding packet. In various embodiments, the QoS requirements may include at least one of waiting time, reliability, data rate, or loss rate. For example, the QoS requirements of a packet may be mapped to the V2X QoS ID (VQI) of the packet. Therefore, the packet sent by the V2X terminal 2310 may have a VQI value corresponding thereto, and there may be a QoS requirement corresponding to the VQI. According to an embodiment, the V2X terminal 2310 may monitor whether the packet of the same VQI can meet the QoS requirements at a predetermined time. In various embodiments, the predetermined time may be preconfigured or configured by a base station.

[0156] In step 2303, the V2X terminal 2310 may report to the base station 2320 that the QoS requirement has not been met. For example, the V2X terminal 2310 may forward a message indicating that the QoS requirement is not met for the data packet being processed by the V2X terminal 2310 (or a QoS requirement non-satisfaction report message) to the base station 2320. In various embodiments, the QoS requirement non-satisfaction report message may include at least one of an ID of a radio bearer that does not meet the QoS requirement, a QoS flow ID (QFI), a type of non-satisfied QoS requirement, a non-satisfaction degree of the non-satisfied QoS requirement, a transmitting terminal ID, or a receiving terminal ID.

[0157] In step 2305, the base station 2320 may send an RRC connection reconfiguration message to the V2X terminal 2310. For example, in response to receiving the QoS requirement non-satisfaction report message, the base station 2320 may send the RRC connection reconfiguration message to the V2X terminal 2310 to reconfigure the radio bearer in which the QoS requirement is not satisfied.

[0158] Fig.24 Illustration of a signal flow between a terminal and another terminal when QoS requirements are not satisfied in V2X communication in a wireless communication system according to various embodiments.

[0159] refer to Fig.24In step 2401, the first V2X terminal 2410 (e.g., V2X terminal 2020) may determine that the QoS requirement cannot be met. In V2X communication, because the first V2X terminal 2410 performs direct data communication with another V2X terminal instead of with a base station, it may be difficult for the base station to determine whether the transmitted service meets the QoS requirement. Therefore, the first V2X terminal 2410 participating in data communication may need to check whether the QoS requirement is met. For example, Fig. 20 At least one of the transmitting V2X terminal 2020 or the receiving V2X terminals 2030 and 2040 participating in the V2X communication shown may determine whether the QoS requirements of the processed data are met. According to an embodiment, the first V2X terminal 2410 may monitor whether a specific packet or data processed in a specific DRB meets the QoS requirements. For example, the first V2X terminal 2410 may monitor the packets scheduled for a predetermined time, thereby determining whether a separate packet or a packet of the same type meets the QoS requirements of the corresponding packet. In various embodiments, the QoS requirements may include at least one of waiting time, reliability, data rate, or loss rate. For example, the QoS requirements of a packet may be mapped to the V2X QoS ID (VQI) of the packet. Therefore, the packet sent by the first V2X terminal 2410 may have a VQI value corresponding thereto, and there may be a QoS requirement corresponding to the VQI. According to an embodiment, the first V2X terminal 2410 may monitor whether the packet of the same VQI can meet the QoS requirements at a predetermined time. In various embodiments, the predetermined time may be preconfigured or configured by a base station. When the first V2X terminal 2410 that monitors whether the QoS requirement is satisfied and the second V2X terminal 2420 (eg, the V2X terminal 2030 or 2040) that performs the RRC configuration are different from each other, reference may be applied. Fig.24 Described embodiments.

[0160] In step 2403, the first V2X terminal 2410 may report to the second V2X terminal 2420 that the QoS requirement has not been met. For example, the first V2X terminal 2410 may forward a message indicating that the QoS requirement is not met for the data packet being processed by the first V2X terminal 2410 (or a QoS requirement non-satisfaction report message) to the second V2X terminal 2420. In various embodiments, the QoS requirement non-satisfaction report message may include at least one of an ID of a radio bearer that does not meet the QoS requirement, a QoS flow ID (QFI), a type of non-satisfied QoS requirement, a degree of non-satisfaction of the non-satisfied QoS requirement, a transmitting terminal ID, or a receiving terminal ID.

[0161] In step 2405, the second terminal 2420 may send an RRC connection reconfiguration message to the first V2X terminal 2410. For example, in response to receiving a QoS requirement unsatisfied report message, the second V2X terminal may send an RRC connection reconfiguration message to the first V2X terminal 2410 to reconfigure the radio bearer in which the QoS requirement is not satisfied. In various embodiments, when the first V2X terminal 2410 is a receiving V2X terminal, Fig.24 The V2X communication scheme may be a multicast scheme or a broadcast scheme, and the number of V2X terminals including the first V2X terminal 2410 capable of sending a QoS requirement non-satisfaction report message may be two or more. According to an embodiment, only a specific terminal and / or a predetermined terminal may be configured to send a QoS requirement non-satisfaction report message.

[0162] Fig.25 Illustration of a signal flow between terminals when QoS requirements are not met in V2X communication in a wireless communication system according to various embodiments.

[0163] refer to Fig.25 In step 2501, the first V2X terminal 2510 (e.g., V2X terminal 2020) may determine that the QoS requirement cannot be met. In V2X communication, because the first V2X terminal 2510 performs direct data communication with another V2X terminal instead of with a base station, it may be difficult for the base station to determine whether the transmitted service meets the QoS requirement. Therefore, the first V2X terminal 2510 participating in data communication may need to check whether the QoS requirement is met. For example, Fig. 20 At least one of the transmitting V2X terminal 2020 or the receiving V2X terminals 2030 and 2040 participating in the V2X communication shown may determine whether the QoS requirements of the processed data are met. According to an embodiment, the first V2X terminal 2510 may monitor whether a specific packet or data processed in a specific DRB meets the QoS requirements. For example, the first V2X terminal 2510 may monitor the packets scheduled at a predetermined time to determine whether a separate packet or a packet of the same type meets the QoS requirements of the corresponding packet. In various embodiments, the QoS requirements may include at least one of waiting time, reliability, data rate, or loss rate. For example, the QoS requirements of a packet may be mapped to the V2X QoS ID (VQI) of the packet. Therefore, the packet sent by the first V2X terminal 2510 may have a VQI value corresponding thereto, and there may be a QoS requirement corresponding to the VQI. According to an embodiment, the first V2X terminal 2510 may monitor whether the packet of the same VQI can meet the QoS requirements at a predetermined time. In various embodiments, the predetermined time may be pre-configured or configured by a base station. When the first V2X terminal 2510 that monitors whether the QoS requirement is met is capable of performing RRC configuration, reference may be applied Fig.25 Described embodiments.

[0164] In step 2503, the first V2X terminal 2510 may send an RRC connection reconfiguration message to the second V2X terminal 2520 (e.g., V2X terminal 2030 or 2040). For example, when the first V2X terminal 2520 determines that the QoS requirement cannot be met, the first V2X terminal 2510 may send an RRC connection reconfiguration message to the second V2X terminal 2520. The transmission of the RRC connection reconfiguration message by the first V2X terminal 2510 may refer to the first V2X terminal 2510 performing reconfiguration of a radio bearer that cannot directly meet the QoS requirement. For example, the first V2X terminal 2510 may send the QoS requirement of the packet processed by the first V2X terminal 2510 to any V2X terminal around it according to a broadcast scheme. The transmission according to the broadcast scheme means that the number of V2X terminals receiving the RRC connection reconfiguration message may be two or more including the second V2X terminal 2520. How the terminal performs the reconfiguration of the radio bearer may be determined based on a predetermined rule. In various embodiments, the predetermined rule may include at least one of an operation of processing a packet of a VQI that cannot meet the QoS requirement in a default bearer, an operation of releasing a radio bearer to which the packet that cannot meet the QoS requirement is sent, an operation of releasing a lowest priority radio bearer among the bearers (in which case, data processed by the released radio bearer can then be processed by the default bearer), or an operation of no longer processing a packet of a VQI that cannot meet the QoS requirement. In various embodiments, when the predetermined rule is applied, the predetermined rule may be applied only to data that is not a safety message.

[0165] Fig.26 A flow chart of a terminal for transmitting a packet by monitoring a QoS requirement in V2X communication in a wireless communication system according to various embodiments is illustrated. Fig.26 A method of operating the V2X terminal 2020 or the V2X terminal 2030 is illustrated.

[0166] refer to Fig.26 In step 2601, the terminal may monitor whether the QoS requirement of the packet corresponding to the specific VQI is met. The terminal that monitors whether the QoS requirement of the packet processed by the terminal is met may determine whether the QoS requirement of the packet corresponding to the VQI of the packet is met for each packet to be processed. In various embodiments, it may be monitored for each packet whether the QoS requirement is met, or whether the data of the same VQI meets the QoS requirement at a preset time.

[0167] In step 2603, the terminal may monitor whether the QoS requirement of the packet corresponding to the VQI is met. When the QoS requirement of the packet corresponding to the VQI is met (step 2603: Yes), the terminal may perform step 2605. In contrast, when the QoS requirement of the packet corresponding to the VQI is not met (step 2603: No), the terminal may perform step 2607.

[0168] In step 2605, the terminal may perform transmission via the radio bearer to which the corresponding packet is transmitted. In other words, since the QoS requirement is satisfied for the radio bearer, the terminal may continuously transmit packets via the existing radio bearer.

[0169] In step 2607, the terminal may send the packet of the VQI or application to the default bearer. In an embodiment, instead of sending the packet to the default bearer, the terminal may no longer process the packet of the VQI or application. In other embodiments, the terminal may not process the packet of the lowest priority VQI previously processed by the terminal, or may send the packet to the default bearer.

[0170] Fig. 27The structure of the signaling radio bearer (SRB) of the base station is illustrated, and a method for notifying the base station of the MCG failure by the terminal 2700 when the MCG failure occurs. SRB is a radio bearer for configuring the radio resource control (RRC) of the base station, and the base station indicates the process of RRC configuration, reconfiguration and reconstruction via SRB. In addition, the terminal 2700 can send a response message via SRB in response to the configuration, reconfiguration and reconstruction message of the base station, and can send a message that should be triggered by the terminal 2700. For example, the terminal 2700 can use SRB to send an SCG failure information message sent when an SCG failure has occurred. SRBs are divided and configured into SRB1, SRB2, SRB3, etc. according to usage. SRB1 2710 and SRB2 2710 are configured between the primary node 2701 and the terminal 2700, and SRB32720 is configured between the secondary node 2702 and the terminal 2700. SRB1 2710 is mainly used for the transmission of messages of the direct connection between the terminal 2700 and the base station. SRB2 2710 is mainly used for the transmission of NAS messages between the core network and the terminal 2700. SRB3 2720 is used for the transmission of messages of the direct connection between the secondary node and the terminal 2700. In this case, for SRB1 2710 and SRB2 2710, RRC and PDCP are located in the primary node 2701 (2711), and RLC and MAC may exist in the primary node 2701 and the secondary node 2702, respectively (2712, 2713). In this case, when the RLC is located only in the MCG, the SRB is called a non-separated SRB, and when the RLC is located in the MCG and the SCG, the SRB is called a separated SRB. For example, SRB1 may be called a separated SRB1. Conversely, for SRB3, RRC and PDCP are located in the secondary node (2721), and RLC and MAC are also located in the secondary node (2722). In Fig. 27 In the embodiment of the present invention, although only certain SRBs are described, a data radio bearer (DRB) to which data is transmitted may also be configured when the terminal 2700 is connected to the base station.

[0171] When the terminal 2700 senses an MCG failure (2730) due to a failure of the MCG RLF, a reconfiguration of the accompanying synchronization, etc., transmission using the MCG is no longer possible. Therefore, it may be necessary to notify the base station that an MCG failure has occurred. In this case, when the SCG link is available, the terminal 2700 can send a corresponding message (2740) using the SCG. In this case, when SRB1 is configured, a separate SRB1 2710 can be used, and when SRB3 is configured, the corresponding MCG failure information can be sent to the secondary node via SRB32720. However, because the anchor node of SRB3 is the secondary node 2720, the corresponding information should be forwarded to the primary node 2710 responsible for the MCG connection. In this case, the content of the fault report message 2740 sent to SRB3 can be forwarded as is. However, according to another embodiment, the secondary node 2720 can use a message other than a fault report message to send information indicating which terminal has suffered an MCG failure and why the MCG failure occurred. Subsequently, the base station or the master node 2710 of the base station may instruct a handover to change the MCG and accompanying synchronization reconfiguration of the terminal 2700. According to certain embodiments, a role swap for exchanging the roles of the master node 2701 and the secondary node 2702 may be instructed.

[0172] For example, the MCG fault information message may include the following information.

[0173] - Which cell group has suffered a failure (eg, was the failure an MCG failure or an SCG failure)?

[0174] - What type of failure has occurred (e.g., was the failure a RLF or a failure with synchronous reconfiguration)?

[0175] - Measurement reports configured by the master node

[0176] - Measurement reports configured by the slave node

[0177] When the secondary cell group is operated by another radio access technology (RAT), the message of the measurement report configured by the secondary node may be encoded by the coding used in the RAT of the secondary cell group.

[0178] Fig.28The SRB structure of the illustrated base station and the method by which the terminal notifies the base station of the SCG failure when an SCG failure occurs. A signaling radio bearer (SRB) is a radio bearer configured by the radio resource control (RRC) of the base station, and the base station indicates the process of RRC configuration, reconfiguration, reconstruction, etc. via the SRB. In addition, the terminal can send a response message in response to the configuration, reconfiguration and reconstruction message of the base station via the SRB, and can send a message that should be triggered by the terminal. For example, an SRB can be used to send an SCG failure information message sent when an SCG failure has occurred. SRBs can be divided and configured into SRB1, SRB2, SRB3, etc. according to usage. SRB1 2810 and SRB2 2810 are configured between the primary node 2801 and the terminal, and SRB3 2820 is configured between the secondary node 2802 and the terminal. SRB1 2810 sends a message for a direct connection between the terminal and the base station. SRB2 2810 is mainly used for the transmission of NAS messages between the core network and the terminal. SRB3 2820 sends a message for a direct connection between the secondary node and the terminal. In this case, for SRB1 2810 and SRB2 2810, RRC and PDCP may be located in the primary node (2811), and RLC and MAC may exist in the primary node and the secondary node, respectively (2812, 2813). In this case, when the RLC is located only in the MCG, the SRB is called a non-separated SRB, and when the RLC is located in the MCG and the SCG, the SRB is called a separated SRB. That is, SRB1 may be called a separated SRB1. Conversely, for SRB3, RRC and PDCP are located in the secondary node (2821), and RLC and MAC are also located in the secondary node (2822). Fig.28 Although only certain SRBs are described in the embodiments, a data radio bearer (DRB) to which data is transmitted may also be configured when a terminal and a base station are connected.

[0179] When the terminal 2800 senses an SCG failure (2830) due to a failure of the SCG RLF, a reconfiguration of the SCG accompanied by synchronization, etc., transmission using the SCG is no longer possible. Therefore, it may be necessary to notify the base station that an MCG failure has occurred. In this case, when the MCG link is available, the corresponding MCG message (2840) can be sent using the SCG. In this case, when SRB1 is configured, SRB1 2810 can be used. Subsequently, the base station or the master node of the base station can instruct an SCG change or a reconfiguration of the synchronization for changing the SCG of the terminal in order to resolve the SCG failure.

[0180] Fig.29The operation process 2900 of the terminal when an MCG failure occurs is illustrated. Due to the expiration of the T310 timer, the terminal can trigger a failure of the primary cell group, that is, an MCG failure, such as an MCG RLF, such as a random access failure or reaching the maximum number of retransmissions of the RLC, other handover failures, failures associated with synchronization reconfiguration, etc. (2901). In the case of an MCG failure, it is impossible to properly perform data transmission to the primary cell group. Therefore, the transmission of all signaling radio bearers (SRBs) and data radio bearers (DRBs) sent to the primary cell group can be suspended. However, at this time, SRB0 should not be suspended because it will be needed when a radio link reconstruction occurs in the future (2903). In addition, because the MAC of the primary cell group can no longer be used, the MAC of the primary cell group can be reset (2905). In addition, when there is a T304 timer operating for the purpose of handover, etc. or another timer being operated, because the operation of the timer is no longer needed, the timer can be stopped (2907). Thereafter, an MCG failure reporting operation can be triggered to notify the base station that an MCG failure has occurred. The notification can be sent via the secondary cell group. The radio bearer used in this case may be a separate SRB1 capable of performing transmission to a secondary cell group, or an SRB3 (2909) performing direct transmission to a secondary node.

[0181] Fig.30 The operation process 3000 of the terminal when an SCG failure occurs is illustrated. For reasons such as the expiration of the T313 timer, the terminal can trigger a failure of the second cell group, that is, an SCG failure, an SCG RLF, such as a random access failure to the SCG or reaching the maximum number of retransmissions in the SCG RLC, other SCG configuration failures, failures of SCG reconfiguration accompanied by synchronization, etc. (3001). In the case of an SCG failure, it is impossible to properly perform data transmission to the secondary cell group. Therefore, the transmission of all signaling radio bearers (SRBs) and data radio bearers (DRBs) sent to the secondary cell group can be suspended (3003). In addition, because the MAC of the secondary cell group can no longer be used, the MAC of the secondary cell group can be reset (3005). In addition, when there is a T304 timer operating for the purpose of switching, etc. or another timer being operated, because the operation of the timer is no longer required, the timer can be stopped (3007). Thereafter, an SCG failure reporting operation can be triggered to notify the base station that an SCG failure has occurred. The notification can be sent via the primary cell group. The radio bearer used in this case may be SRB1 (3009) capable of performing transmission to the primary cell group.

[0182] Fig.31The protocol structure of the separated SRB1 is illustrated. The separated SRB1 3101 can be configured to send RRC messages, and can have a layer of RRC 3102, a layer of packet data convergence protocol (PDCP) 3103, two or more layers of radio link control (RLC) 3104 and 3114, two or more layers of medium access control (MAC) 3105 and 3115, and two or more layers of physical layer (PHY) 3106 and 3116. In this case, the term "separation" refers to the presence of two or more RLC devices 3104 and 3114 for the corresponding radio bearer. In this case, the term "RLC device" can be used interchangeably with the term "RLC bearer" and "logical channel". The cell group for the separated SRB1 can include a primary cell group 3107 and a secondary cell group 3117. In addition, the RRC of the separated SRB1 can be located at the master node, and the master node can manage the RRC connection of the terminal. In this case, the RLC devices of the split SRB1 3104 and the split SRB1 3114 can be configured to be divided into a main RLC (main path) device used regardless of the amount of data to be transmitted and a secondary RLC (secondary path) device used when the data to be transmitted is greater than or equal to the threshold ul-DataSplitThreshold. The base station can notify the terminal of the threshold of the data amount through the RRC configuration. In addition, in the corresponding split SRB1, packet replication can be performed for replicating packets in the PDCP device of the transmitter and transmitting all data to multiple RLC devices. When packet replication transmission is activated, multiple RLC devices can be used for packet transmission at the same time.

[0183] Fig.32 The protocol structure of a non-separated signaling radio bearer 3 (SBR3) is illustrated. A non-separated SRB3 3210 may be configured to send an RRC message, and may have a layer of RRC 3220, a layer of PDCP 3230, a layer of RLC 3240, a layer of MAC 3250, and a layer of PHY 3260. In this case, the term "separated" refers to the presence of one RLC device 3240 for the corresponding radio bearer. In this case, the term "RLC device" may be used interchangeably with the terms "RLC bearer" and "logical channel". The cell group for a non-separated SRB3 may be a secondary cell group 3270. In addition, the RRC of the SRB3 may be located at a secondary node, and the secondary node may manage certain RRC connections of the terminal.

[0184] Fig.33 The figure shows the conflict scenario of MCG failure and SCG failure. Figure 2 and Fig.29As described above, when an MCG failure occurs (3330), the terminal 3300 can use a separate SRB1 3310 or SRB3 3320 connected to the SCG to send an MCG failure information message to the base station. However, when an MCG failure is sensed but an SCG failure has occurred and the reference Fig.30 When the described SCG fault operation is in progress (3340), the MCG fault report message cannot be sent to the SCG link. In addition, when the SCG fault is not sensed when the MCG fault report is sensed but the MCG report message has not been sent (3330), or even when the SCG fault is sensed after the MCG report message is sent but the RRC message is not received from the base station through SRB1, the recovery process based on the MCG fault report cannot be performed normally. Therefore, in this case, the MCG fault information cannot be reported (3350). Therefore, in this case, the terminal is required to perform the RRC reconstruction process, and the terminal can cancel the transmission of the previously triggered MCG fault information message or SCG fault information message.

[0185] SRB1 3310 and SRB2 3310 are configured between the primary node 3301 and the terminal, and SRB3 3320 is configured between the secondary node 3302 and the terminal. In this case, for SRB1 3310 and SRB2 3310, RRC and PDCP may be located in the primary node (3311), and RLC and MAC may exist in the primary node and the secondary node, respectively (3312, 3313). In this case, when RLC is located only in MCG, SRB is called non-separated SRB, and when RLC is located in MCG and SCG, SRB is called separated SRB. That is, SRB1 may be called separated SRB1. On the contrary, for SRB3, RRC and PDCP are located in the secondary node (3321), and RLC and MAC are also located in the secondary node (3322).

[0186] When Fig.33 The specific operations performed when an MCG failure occurs in an embodiment are as follows.

[0187] -When an SCG failure has been declared at the time of MCG failure and the SCG failure has not been restored (when an SCG failure information message has not been sent or when an RRC message has not been received from the base station after sending), the terminal performs the RRC reestablishment procedure. In this case, it is declared what SCG failure has been restored after the declaration of the SCG failure, regardless of whether the SCG failure has been declared.

[0188] -When the SCG failure has not been declared at the time of MCG failure, or when the SCG failure has been declared but recovered, the terminal may send an MCG failure information message to a separate SRB1 or SRB3.

[0189] In another embodiment, operations in which an SCG failure has been declared but not recovered may be replaced depending on whether transmission to or reception from the SCG has been suspended.

[0190] -When SCG transmission / reception of SRB and DRB is suspended upon MCG failure, the terminal performs the RRC re-establishment procedure.

[0191] -When SCG transmission / reception of SRB and DRB is not suspended upon MCG failure, the terminal may send an MCG failure information message to the separated SRB1 or SRB3.

[0192] -When the MCG failure report message has not been sent after the MCG failure, or when an RRC message for solving the corresponding problem has not been received from the base station after the MCG failure report message, but an SCG failure occurs (SCG transmission or reception is suspended), the terminal performs the RRC reconstruction process.

[0193] When the terminal needs to perform the RRC reconstruction process, the terminal can cancel the transmission of the previously triggered MCG fault information message or SCG fault information message.

[0194] Fig.34 The figure shows another conflict scenario of MCG failure and SCG failure. Figure 3 and Fig.30 As described above, when an SCG failure occurs (3430), the terminal 3400 can use the SRB1 connected to the MCG to send an SCG failure information message to the base station. However, when the SCG failure is sensed but the MCG failure has occurred and the reference Fig.29 When the described MCG fault operation is in progress (3440), the SCG fault report message cannot be sent to the MCG link. In addition, when the MCG fault is not sensed when the SCG fault report is sensed but the SCG report message has not been sent (3430), or even when the MCG fault is sensed after the SCG report message is sent but the RRC message is not received from the base station through SRB1, the recovery process based on the SCG fault report cannot be performed normally. Therefore, in this case, the SCG fault information cannot be reported (3450). Therefore, in this embodiment, the terminal is required to perform the RRC reconstruction process, and the terminal can cancel the transmission of the previously triggered MCG fault information message or SCG fault information message.

[0195] SRB1 3410 and SRB2 3410 are configured between the primary node 3401 and the terminal, and SRB3 3420 is configured between the secondary node 3402 and the terminal. In this case, for SRB1 3410 and SRB2 3410, RRC and PDCP may be located in the primary node (3411), and RLC and MAC may exist in the primary node and the secondary node, respectively (3412, 3413). In this case, when RLC is located only in MCG, SRB is called non-separated SRB, and when RLC is located in MCG and SCG, SRB is called separated SRB. That is, SRB1 may be called separated SRB1. On the contrary, for SRB3, RRC and PDCP are located in the secondary node (3421), and RLC and MAC are also located in the secondary node (3422).

[0196] When Fig.34 The specific operations performed when an SCG failure occurs in an embodiment are as follows.

[0197] -When MCG failure has been declared and SCG failure has not been restored at the time of SCG failure (when MCG failure information message has not been sent, or when RRC message has not been received from the base station after transmission), the terminal performs the RRC reestablishment procedure. In this case, what MCG failure has been restored after the declaration of MCG failure, regardless of whether MCG failure has been declared.

[0198] - When MCG failure has not been declared at the time of SCG failure, or when MCG failure has been declared but recovered, the terminal may send an SCG failure information message to the detached SRB1.

[0199] In another embodiment, the operation in which an MCG failure has been declared but not restored may be replaced depending on whether transmission to or reception from the MCG has been suspended.

[0200] -When MCG transmission / reception of SRB and DRB is suspended upon SCG failure, the terminal performs the RRC re-establishment procedure.

[0201] -When MCG transmission / reception of SRB and DRB is not suspended upon SCG failure, the terminal may send an SCG failure information message to SRB1.

[0202] -When an SCG failure report message has not been sent after an SCG failure, or when an MCG failure occurs (MCG transmission or reception is suspended) although an RRC message for solving the corresponding problem has not been received from the base station after the SCG failure report message, the terminal performs an RRC reestablishment process.

[0203] When the terminal is required to perform the RRC reconstruction process, the terminal can cancel the transmission of the previously triggered MCG fault information message or SCG fault information message.

[0204] Fig.35 The detailed operation process 3500 of the terminal when an MCG failure occurs is shown. An MCG failure may occur in the terminal through at least one of the following processes.

[0205] -MCG Radio Link Failure (RLF)

[0206] - Failures with synchronous reconfiguration

[0207] -SRB1 / 2 integrity check failure

[0208] -RRC reconfiguration failure

[0209] Here, MCG RLF may occur through at least one of the following processes.

[0210] - Expiration of T310 timer

[0211] -Random access problem

[0212] - The maximum number of RLC retransmissions has been reached

[0213] When an MCG failure occurs through at least one of the above processes (3501), the terminal can check whether to suspend the transmission of SRBs and DRBs to the SCG (3503). When the transmission of DRBs and SRBs sent to the SCG is suspended, the terminal can perform an RRC reconstruction process (3505). In this case, the MCG failure information message and SCG failure information message that have been triggered can be canceled. Otherwise, when the transmission of DRBs and SRBs sent to the SCG is not suspended, the terminal can send an MCG failure information message (3507) via the SCG through the MCG failure reporting process. The radio bearer used in this case can be a separated SRB1 or SRB3.

[0214] Fig.36 The detailed operation process 3600 of the terminal when an SCG failure occurs is illustrated. The SCG failure in the terminal may occur through at least one of the following processes.

[0215] -SCG Radio Link Failure (RLF)

[0216] - Failures with synchronized SCG reconfiguration

[0217] -SCG Change Glitch

[0218] -SRB3 integrity check failure

[0219] Here, SCG RLF may occur through at least one of the following processes.

[0220] - Expiration of T313 timer

[0221] -SCG random access problem

[0222] - Reached the maximum number of SCG RLC retransmissions

[0223] When an SCG failure occurs through at least one of the above processes (3601), the terminal can check whether to suspend the transmission of SRBs and DRBs sent to the MCG except SRB0 (3603). When the transmission of DRBs and SRBs sent to the MCG other than SRB0 is suspended, the terminal can perform the RRC reconstruction process (3605). In this case, the MCG failure information message and the SCG failure information message that have been triggered can be canceled. Otherwise, when the transmission of DRBs and SRBs sent to the MCG is not suspended, the terminal can send an SCG failure information message (3607) via the MCG through the SCG failure reporting process. The radio bearer used in this case can be SRB1.

[0224] Fig.37 The detailed operation process of the terminal when an MCG failure occurs is shown in FIG3700. An MCG failure may occur in the terminal through at least one of the following processes.

[0225] -MCG Radio Link Failure (RLF)

[0226] - Failures with synchronous reconfiguration

[0227] -SRB1 / 2 integrity check failure

[0228] -RRC reconfiguration failure

[0229] Here, MCG failure may occur through at least one of the following processes.

[0230] - Expiration of T310 timer

[0231] -Random access problem

[0232] - The maximum number of RLC retransmissions has been reached

[0233] When an MCG failure occurs through at least one of the above processes (3701), the operation of the terminal may vary depending on whether the terminal is configured to perform the MCG failure reporting process. The base station may allow the terminals connected to it to perform the same operation, but may allow each terminal to perform different processes according to the embodiment. For example, each terminal is similarly configured to send or not send an MCG failure information message. In this case, each terminal may or may not be configured to send or not send an MCG failure information message through an RRC configuration message. In another embodiment, each terminal may be configured to send or not send an MCG failure information message to the system information. When each terminal is not configured to perform an MCG failure reporting operation (3703: No), the terminal performs an RRC reconstruction process (3707) when an MCG failure occurs.

[0234] When each terminal is configured to perform an MCG fault reporting operation (3703: Yes), the terminal may check whether to suspend the transmission of SRBs and DRBs to the SCG (3705). When the transmission of DRBs and SRBs sent to the SCG is suspended, the terminal may perform an RRC reestablishment procedure (3707). In this case, the MCG fault information message and the SCG fault information message that have been triggered may be canceled. Otherwise, when the transmission of DRBs and SRBs sent to the SCG is not suspended, the terminal may send an MCG fault information message (3709) via the SCG through the MCG fault reporting procedure. The radio bearer used in this case may be a separate SRB1 or SRB3.

[0235] Fig.38 The diagram illustrates a method for configuring the MCG fault information message transmission process and the MCG fault report message transmission process. When an MCG fault occurs in the terminal 3810, the operation of the terminal may vary depending on whether the terminal is configured to perform the MCG fault reporting process. The base station 3820 may allow the terminals connected to it to perform the same operation, but may allow each terminal to perform different processes according to the embodiment. For example, each terminal may be similarly configured to send or not send an MCG fault information message. In this case, each terminal may be configured to send or not send an MCG fault information message through an RRC configuration message (3830). The message may be sent in a state where it is included in an RRC establishment message or an RRC reconstruction message instead of the RRC configuration message. When the terminal receives the configuration message, the terminal may complete the received configuration and then send a configuration completion message to the base station (3840). In Fig.38 In the embodiment of the present invention, a method has been described in which the MCG fault information process is configured based on the RRC message notification. However, in another embodiment, the terminal may be configured to send or not send the MCG fault information message to the system information. When the terminal is not configured to perform the MCG fault reporting operation, the terminal performs the reconstruction process when an MCG fault occurs.

[0236] As above reference Fig.38 The information about the configuration for MCG fault reporting may be sent via an RRC message. According to an embodiment, the information about the configuration for MCG fault reporting may include the following information.

[0237] According to an embodiment, the RRC configuration message 3830 may include an indicator instructing the terminal to perform an MCG failure reporting procedure or an RRC reestablishment procedure.

[0238] When the terminal is configured to perform the MCG fault reporting process, when the trigger of the RLF for the MCG described in another embodiment is detected, the MCG RLF report message may be sent to the RLC device connected to the SCG. In this case, when the separation SRB1 is configured, the MCG RLF report message may be sent to the separation SRB1. When SRB1 is not configured and SRB3 is configured, the MCG RLF report message may be sent to SRB3. When both separation SRB1 and SRB3 are not configured, it is impossible to perform MCGRLF reporting. Therefore, the terminal can declare an RRC configuration failure without sending the RRC configuration completion message 3840. According to another embodiment, if both separation SRB1 and SRB3 are not configured, the terminal may request RRC reconstruction from the base station.

[0239] When the terminal is configured not to perform the MCG failure reporting procedure, that is, when the terminal is configured to perform the RRC re-establishment procedure, when the terminal detects the triggering of RLF for the MCG, the terminal may request RRC re-establishment with the base station.

[0240] Fig.39 The configuration of a base station in a wireless communication system according to various embodiments is illustrated. Terms such as "-part" and "-unit" to be used hereinafter refer to a unit for processing at least one function or operation, and can be implemented by hardware, software, or a combination of hardware and software.

[0241] refer to Fig.39 , the base station 3900 may include a transceiver 3910, a base station controller 3920, and a storage device 3930. In various embodiments, the base station controller 3920 may also be referred to as a circuit, an application specific integrated circuit, or at least one processor.

[0242] The transceiver 3910 may transmit / receive signals to / from other network entities. The transceiver 3910 may transmit system information to, for example, a terminal, and may transmit a synchronization signal or a reference signal.

[0243] The base station controller 3920 may control the overall operation of the base station according to various embodiments. For example, the base station controller 3920 may control the base station to perform the above-mentioned operations of the base station.

[0244] The storage device 3930 may store at least one of information transmitted / received via the transceiver 3910 and information generated via the base station controller 3920 .

[0245] In various embodiments, the base station 3900 may be the same as the base station 110, or may be included in the base station 110. In this case, the transceiver 3910 may be included in the wireless communication unit 210 and / or the backhaul communication unit 220, the base station controller 3920 may be included in the controller 240, and the storage device 3930 may be included in the storage device 230.

[0246] Fig.40 The configuration of a terminal in a wireless communication system according to various embodiments is illustrated. Terms such as "-part" and "-unit" to be used hereinafter refer to a unit for processing at least one function or operation, and can be implemented by hardware, software, or a combination of hardware and software.

[0247] refer to Fig.40 , the terminal 4000 may include a transceiver 4010, a terminal controller 4020, and a storage device 4030. According to various embodiments, the terminal controller 4020 may also be referred to as a circuit, an application specific integrated circuit, or at least one processor.

[0248] The transceiver 4010 may transmit / receive signals to / from other network entities. The transceiver 4010 may receive system information from, for example, a base station, and may receive a synchronization signal or a reference signal.

[0249] The terminal controller 4020 may control the overall operation of the terminal according to various embodiments. For example, the terminal controller 4020 may control the terminal to perform the above-mentioned operations of the terminal.

[0250] The storage device 4030 may store at least one of information transmitted / received via the transceiver 4010 and information generated via the terminal controller 4020 .

[0251] In various embodiments, the terminal 4000 may be the same as the terminal 120 or the terminal 130, or may be included in the terminal 120 or the terminal 130. In this case, the transceiver 4010 may be included in the communication unit 310, the controller 4020 may be included in the controller 330, and the storage device 4030 may be included in the storage device 320.

[0252] The methods according to the embodiments set forth in the claims and / or specification of the present disclosure may be implemented in hardware, software, or a combination of hardware and software.

[0253] When the method is implemented by software, a computer-readable storage medium for storing one or more programs (software modules) may be provided. One or more programs stored in the computer-readable storage medium may be configured to be executed by one or more processors in an electronic device. At least one program may include instructions that cause the electronic device to perform the method according to various embodiments of the present disclosure as defined in the attached claims and / or disclosed herein.

[0254] The program (software module or software) can be stored in a non-volatile memory, including random access memory and flash memory, read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), magnetic disk storage, compact disk ROM (CD-ROM), digital versatile disk (DVD) or other types of optical storage devices or tape cassettes. Alternatively, any combination of some or all of the above can form a memory in which the program is stored. In addition, a plurality of such memories can be included in the electronic device.

[0255] In addition, the program can be stored in an attachable storage device accessible through a communication network, such as the Internet, an intranet, a local area network (LAN), a wide area network (WAN), and a storage area network (SAN), or a combination thereof. Such a storage device can be accessed via an external port of the electronic device. In addition, a separate storage device on the communication network can be accessed by a portable electronic device.

[0256] In the specific embodiments of the present disclosure described above, the components included in the present disclosure are expressed in the singular or plural according to the specific embodiments presented. However, the singular form or plural form is selected for the convenience of the description of the situation suitable for presentation, and the various embodiments of the present disclosure are not limited to its single element or multiple elements. In addition, multiple elements represented in the description can be configured as a single element or a single element in the description can be configured as multiple elements.

[0257] Although the present disclosure has been shown and described with reference to some exemplary embodiments of the present disclosure, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the present disclosure. Therefore, the scope of the present disclosure should not be defined as being limited to the embodiments, but should be defined by the appended claims and their equivalents.

[0258] Although the present disclosure has been described in various embodiments, various changes and modifications may be suggested to one skilled in the art. The present disclosure is intended to encompass such changes and modifications as fall within the scope of the appended claims.

Claims

1. A method performed by a user equipment UE configured with a primary cell group MCG and a secondary cell group SCG in a wireless communication system, the method comprising: Detecting radio link failure RLF of MCG; Identify whether to suspend SCG transmission; In case of suspending SCG transmission, performing the connection reestablishment process; and Without suspending SCG transmission: Based on the detected RLF of the MCG, suspend the MCG transmission of all signaling radio bearers (SRBs) and data radio bearers (DRBs) except SRB0; Reconfigure the MCG media access control (MAC) based on the detected RLF of the MCG; In case that a separate SRB1 is configured for the UE, information about the RLF of the MCG is sent to the secondary base station associated with the SCG via the separate SRB1; as well as In case SRB3 is configured for the UE, information about the RLF of the MCG is sent to the secondary base station associated with the SCG via SRB3.

2. The method according to claim 1, in, RLF of the MCG is detected based on expiration of the T310 timer, a random access problem indication, or reaching the maximum number of retransmissions of the Radio Link Control (RLC).

3. The method of claim 1, further comprising: Without suspending SCG transmission and with separate SRB1 configured for the UE, the primary path to the SCG is set.

4. A user equipment UE configured with a primary cell group MCG and a secondary cell group SCG in a wireless communication system, the UE comprising: Transceiver; and at least one processor coupled to the transceiver and configured to: Detecting the radio link failure RLF of the MCG, Identify whether to suspend SCG transmission; In case of suspending SCG transmission, performing the connection reestablishment process; and Without suspending SCG transmission: Based on the detected RLF of the MCG, suspend the MCG transmission of all signaling radio bearers (SRBs) and data radio bearers (DRBs) except SRB0; Reconfigure the MCG media access control (MAC) based on the detected RLF of the MCG; In case that a separate SRB1 is configured for the UE, information about the RLF of the MCG is sent to the secondary base station associated with the SCG via the separate SRB1; as well as In case SRB3 is configured for the UE, information about the RLF of the MCG is sent to the secondary base station associated with the SCG via SRB3.

5. The UE according to claim 4, in, RLF of the MCG is detected based on expiration of the T310 timer, a random access problem indication, or reaching the maximum number of radio link control (RLC) retransmissions.

6. The UE according to claim 4, in, The at least one processor is further configured to: Without suspending SCG transmission and with separate SRB1 configured for the UE, the primary path to the SCG is set.

Images