KR20200112609A - Method and apparatus for recovering connection failure to network in next generation mobile communication system - Google Patents

Abstract

The present disclosure relates to a communication technique for fusing a 5^th generation (5G) communication system with an Internet of things (IoT) technology to support a higher data transmission rate than that of a 4^th generation (4G) system and a system thereof. The present disclosure can be applied to an intelligent service (for example, smart home, smart building, smart city, smart car or connected car, healthcare, digital education, retail business, security and safety related services, etc.) based on a 5G communication technology and an IoT-related technology. The present invention relates to a method for quickly recovering a network connection failure in a next-generation mobile communication system, and an apparatus thereof. According to the present invention, a control signal processing method in a wireless communication system comprises the steps of: receiving a first control signal transmitted from a base station; processing the first control signal received; and transmitting a second control signal generated based on the processing to the base station.

Description

Method and apparatus for recovering network and connection failure in next-generation mobile communication system {METHOD AND APPARATUS FOR RECOVERING CONNECTION FAILURE TO NETWORK IN NEXT GENERATION MOBILE COMMUNICATION SYSTEM}

The present invention relates to a method and apparatus for quickly recovering when a network connection failure occurs in a next-generation mobile communication system.

Efforts are being made to develop an improved 5G communication system or a pre-5G communication system in order to meet the increasing demand for wireless data traffic after the commercialization of 4G communication systems. For this reason, the 5G communication system or the pre-5G communication system is called a communication system after a 4G network (Beyond 4G Network) or a system after an LTE system (Post LTE). In order to achieve a high data rate, the 5G communication system is being considered for implementation in the ultra-high frequency (mmWave) band (eg, such as the 60 Giga (60 GHz) band). In order to mitigate the path loss of radio waves in the ultra-high frequency band and increase the transmission distance of radio waves, in 5G communication systems, beamforming, massive MIMO, and Full Dimensional MIMO (FD-MIMO) ), array antenna, analog beam-forming, and large scale antenna technologies are being discussed. In addition, in order to improve the network of the system, in 5G communication system, advanced small cell, advanced small cell, cloud radio access network (cloud RAN), ultra-dense network , Device to Device communication (D2D), wireless backhaul, moving network, cooperative communication, CoMP (Coordinated Multi-Points), and interference cancellation And other technologies are being developed. In addition, in the 5G system, advanced coding modulation (ACM) methods such as Hybrid FSK and QAM Modulation (FQAM) and SWSC (Sliding Window Superposition Coding), advanced access technologies such as Filter Bank Multi Carrier (FBMC), NOMA (non orthogonal multiple access), and sparse code multiple access (SCMA) have been developed.

Meanwhile, the Internet is evolving from a human-centered connection network in which humans create and consume information, to an Internet of Things (IoT) network that exchanges and processes information between distributed components such as objects. IoE (Internet of Everything) technology, which combines IoT technology with big data processing technology through connection with cloud servers, is also emerging. In order to implement IoT, technology elements such as sensing technology, wired/wireless communication and network infrastructure, service interface technology, and security technology are required, and recently, a sensor network for connection between objects, machine to machine , M2M), and MTC (Machine Type Communication) technologies are being studied. In the IoT environment, intelligent IT (Internet Technology) services that create new value in human life by collecting and analyzing data generated from connected objects can be provided. IoT is the field of smart home, smart building, smart city, smart car or connected car, smart grid, healthcare, smart home appliance, advanced medical service, etc. through the convergence and combination of existing IT (information technology) technology and various industries. Can be applied to.

Accordingly, various attempts have been made to apply a 5G communication system to an IoT network. For example, technologies such as sensor network, machine to machine (M2M), and MTC (Machine Type Communication) are implemented by techniques such as beamforming, MIMO, and array antenna. There is. As the big data processing technology described above, a cloud radio access network (cloud RAN) is applied as an example of the convergence of 5G technology and IoT technology.

In order to support a service having a high data rate and low transmission delay in a next-generation mobile communication system, the base station needs to quickly configure a frequency aggregation technology (CA) or a dual connectivity (DC) technology to the terminal.

When a connection failure occurs in Spcell (Pcell or Pscell) or Scell or MCG (Master Cell group in dual connectivity) or SCG (Secondary Cell group in dual connectivity) when frequency aggregation technology or dual access technology is configured for the terminal If the connection between the network and the network is completely disconnected, data loss may occur even in the cell or cell group in which the connection was maintained, and data transmission delay may occur.

The present invention for solving the above problem is a control signal processing method in a wireless communication system, the method comprising: receiving a first control signal transmitted from a base station; Processing the received first control signal; And transmitting a second control signal generated based on the processing to the base station.

In order to support a service having a high data rate and low transmission delay in a next-generation mobile communication system, the base station needs to quickly configure a frequency aggregation technology (CA) or a dual connectivity (DC) technology to the terminal. However, when the frequency aggregation technology or dual access technology is configured for the terminal as described above, connection failure occurs in Spcell (Pcell or Pscell) or Scell or MCG (Master Cell group in dual connectivity) or SCG (Secondary Cell group in dual connectivity). When a connection occurs, a method of restoring a connection to a cell or cell group in which the connection is maintained or adding a new connection without completely disconnecting the connection between the terminal and the network is proposed.

1A is a diagram showing the structure of an LTE system to which the present invention can be applied.
1B is a diagram showing a radio protocol structure in an LTE system to which the present invention can be applied.
1C is a diagram showing the structure of a next-generation mobile communication system to which the present invention can be applied.
1D is a diagram showing a radio protocol structure of a next-generation mobile communication system to which the present invention can be applied. .
1E shows that in the next-generation mobile communication system of the present invention, a terminal switches from an RRC idle mode or an RRC inactive mode to an RRC connected mode, and a base station is a carrier aggregation technology or dual access. A diagram showing a procedure for setting a technology to a terminal.
1F is a diagram showing the structure of a protocol layer apparatus of a terminal in which dual access technology is configured in the present invention.
1G is a diagram showing the structure of a protocol layer apparatus of a terminal in which a frequency aggregation technology is configured in the present invention.
1H shows that if a wireless connection failure (MCG wireless connection failure) with a base station (or cell) occurs in a Pcell in a terminal configured with a carrier aggregation technology or dual access technology in embodiments of the present invention, the terminal continues data transmission in the Scell or SCG. A specific Scell or SCG to transmit and receive, recover a Pcell or MCG, change to another Pcell or MCG, release a Pcell or MCG in which the radio failure has occurred, or convert a Scell or SCG with a current connection to a Pcell or MCG It shows the specific terminal operation that reports the PCell's wireless connection failure (MCG wireless connection failure).
Figure 1i shows the structure of a terminal to which an embodiment of the present invention can be applied.
1J is a block diagram of a TRP in a wireless communication system to which an embodiment of the present invention can be applied.

Hereinafter, the operating principle of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, a detailed description thereof will be omitted. In addition, terms to be described later are terms defined in consideration of functions in the present invention, which may vary depending on the intention or custom of users or operators. Therefore, the definition should be made based on the contents throughout this specification.

In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, a detailed description thereof will be omitted. Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

A term for identifying an access node used in the following description, a term for network entities, a term for messages, a term for an interface between network objects, a term for various identification information And the like are illustrated for convenience of description. Therefore, the present invention is not limited to the terms described below, and other terms referring to objects having an equivalent technical meaning may be used.

For convenience of description below, the present invention uses terms and names defined in the 3GPP 3rd Generation Partnership Project Long Term Evolution (LTE) standard. However, the present invention is not limited by the terms and names, and can be applied equally to systems conforming to other standards. In the present invention, the eNB may be used interchangeably with gNB for convenience of description. That is, a base station described as an eNB may represent a gNB.

In the present invention, a terminal configured with a frequency aggregation technology (Carrier Aggregation, CA) or dual connectivity technology (Dual connectivity, DC) is considered, and the proposed method is specified using the following terms.

-Pcell (Primary Cell): refers to a serving cell used by the UE when initially establishing a connection with a base station, and establishes a connection by transmitting and receiving a major RRC message using the Pcell. In addition, since the Pcell always has PUCCH transmission resources, it can indicate HARQ ACK or NACK, and both uplink and downlink are always configured, and as a reference cell for timing adjustment (Timing Advance, Primary Timing Advance Group (pTAG)). Can be used. For example, when a frequency integration technique is set after a Pcell is set and an Scell is added, the Scell may perform uplink data transmission by referring to the timing adjustment value of the Pcell. And when dual access technology is set, Pcell means a PCell of MCG (Master Cell Group).

-MCG (Master Cell Group): refers to a serving cell to which the UE initially establishes a connection with the base station or a group of cells supported by the base station. When dual access technology is configured, major RRC messages are transmitted or received through the MCG.

-SCG (Secondary Cell Group): The terminal establishes a connection with the base station and can add cells of other base stations in addition to the MCG. In this case, it refers to a group of cells supported by other base stations, and when dual access technology is configured, It may be added to increase the additional data rate or to efficiently support the mobility of the terminal.

-PScell (Primary Secondary Cell): When a UE establishes a connection with a base station and a group of cells of another base station is added in addition to the MCG, and dual access technology is configured, the cell corresponding to the Pcell in the SCG is called a PScell.

-Scell (Secondary Cell): Cells additionally configured by the base station in order to set the carrier aggregation technology after the terminal establishes a connection with the base station for the first time is called an Scell. The SCell may have PUCCH transmission resources according to the base station configuration, and the uplink or downlink may be configured according to the configuration of the base station, and also timing adjustment according to the configuration of the base station (Timing Advance, Secondary Timing Advance Group (sTAG)). ) Can be used as a reference cell. For example, when a frequency integration technique is set after a Pcell is set, Scells are added and sTAG is set, other Scells of the sTAG may perform uplink data transmission with reference to the timing adjustment value of the designated Scell. In addition, when the dual access technology is configured for the terminal, Scell means Scells excluding PCells of MCG (Master Cell Group) or Scells excluding PScells of Secondary Cell Group (SCG).

In the present invention, a wireless connection failure with a base station (or cell) in a PCell or MCG or SCG or Scell in a terminal configured with a frequency aggregation technology (Carrier Aggregation, CA) or dual connectivity technology (Dual connectivity, DC) (for example, radio link failure) ) Occurs, if there is a cell (PCell or PScell or Scell) or cell group (MCG or SCG) in which wireless connection with the base station (or cell) is maintained among the Pcell, MCG, SCG or Scell, completely disconnect and reconnect Rather, it proposes a method of transmitting and receiving data as it is with the cell or cell group in which the wireless connection is maintained, and recovering the disconnected cell or cell group, or establishing a new connection. Alternatively, a method of abandoning the disconnected cell or cell group and changing the cell or cell group for which the connection is maintained to a Pcell or MCG is also proposed.

The present invention considers the following embodiments and proposes efficient procedures.

In the first embodiment of the present invention, a case in which a connection between an MCG and a base station (or cell) is maintained in a terminal in which dual access technology is configured, and a wireless connection failure with the base station (or cell) occurs in the SCG is considered.

In the second embodiment of the present invention, consider a case in which the SCG maintains a connection with a base station (or cell) in a terminal configured with dual access technology, and a wireless connection failure with the base station (or cell) occurs in the MCG.

In the third embodiment of the present invention, a Pcell or Pscell (when a dual access technology is also configured) in a terminal configured with a frequency aggregation technology maintains a connection with a base station (or cell), and a radio connection fails with a base station (or cell) in the Scell. Consider the case where

In the fourth embodiment of the present invention, the Scell is connected to the base station (or cell) in the terminal with the frequency aggregation technology configured, and the Pcell or Pscell (when the dual access technology is also configured) fails to connect to the base station (or cell). Consider the case where

The above embodiments can be extended and applied even when both the frequency aggregation technology and the dual access technology are configured in the terminal.

In the following of the present invention, a specific method and efficient operation of a base station or an efficient operation of a terminal are proposed for the above embodiments.

1A is a diagram showing the structure of an LTE system to which the present invention can be applied.

Referring to Figure 1a, as shown, the radio access network of the LTE system is a next-generation base station (Evolved Node B, hereinafter ENB, Node B or base station) (1a-05, 1a-10, 1a-15, 1a-20) and It is composed of MME (1a-25, Mobility Management Entity) and S-GW (1a-30, Serving-Gateway). User Equipment (hereinafter, referred to as UE or terminal) 1a-35 accesses an external network through ENBs 1a-05 to 1a-20 and S-GW 1a-30.

In FIG. 1A, ENBs 1a-05 to 1a-20 correspond to the existing node B of the UMTS system. The ENB is connected to the UEs 1a-35 through a radio channel and performs a more complex role than the existing Node B. In the LTE system, all user traffic including real-time services such as VoIP (Voice over IP) through the Internet protocol are serviced through a shared channel, so status information such as buffer status, available transmission power status, and channel status of UEs A device that collects and schedules is required, and ENB (1a-05 ~ 1a-20) is in charge of this. One ENB typically controls multiple cells. For example, in order to implement a transmission rate of 100 Mbps, the LTE system uses, for example, an orthogonal frequency division multiplexing (OFDM) in a 20 MHz bandwidth as a radio access technology. In addition, an adaptive modulation and coding method (hereinafter referred to as AMC) that determines a modulation scheme and a channel coding rate according to the channel state of the terminal is applied. The S-GW 1a-30 is a device that provides a data bearer, and creates or removes a data bearer under the control of the MME 1a-25. The MME is a device responsible for various control functions as well as mobility management functions for a terminal, and is connected to a plurality of base stations.

1B is a diagram showing a radio protocol structure in an LTE system to which the present invention can be applied.

Referring to Figure 1b, the radio protocol of the LTE system is PDCP (Packet Data Convergence Protocol 1b-05, 1b-40), RLC (Radio Link Control 1b-10, 1b-35), MAC (Medium Access Control 1b-15, 1b-30). PDCP (Packet Data Convergence Protocol) (1b-05, 1b-40) is in charge of operations such as IP header compression/restore. The main functions of PDCP are summarized as follows.

-Header compression and decompression (ROHC only)

-Transfer of user data

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

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

-Duplicate detection of lower layer SDUs at PDCP re-establishment procedure for RLC AM

-Retransmission of PDCP SDUs at handover and, for split bearers in DC, of PDCP PDUs at PDCP data-recovery procedure, for RLC AM

-Encryption and decryption function (Ciphering and deciphering)

-Timer-based SDU discard in uplink.

Radio Link Control (hereinafter referred to as RLC) (1b-10, 1b-35) performs ARQ operation by reconfiguring a PDCP packet data unit (PDU) to an appropriate size. The main functions of RLC are summarized as follows.

-Data transfer function (Transfer of upper layer PDUs)

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

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

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

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

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

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

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

-RLC re-establishment

The MACs 1b-15 and 1b-30 are connected to several RLC layer devices configured in one terminal, and perform an operation of multiplexing RLC PDUs to MAC PDUs and demultiplexing RLC PDUs from MAC PDUs. The main functions of MAC are summarized as follows.

-Mapping between logical channels and transport channels

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

-Scheduling information reporting function

-HARQ function (Error correction through HARQ)

-Priority handling between logical channels of one UE

-Priority handling between UEs by means of dynamic scheduling

-MBMS service identification

-Transport format selection

-Padding function

The physical layer (1b-20, 1b-25) channel-codes and modulates upper layer data, converts it into OFDM symbols, and transmits it to the radio channel, or demodulates OFDM symbols received through the radio channel and decodes the channel and delivers it to the upper layer. Do the action.

1C is a diagram showing the structure of a next-generation mobile communication system to which the present invention can be applied.

Referring to Figure 1c, as shown, the radio access network of the next-generation mobile communication system (hereinafter NR or 5G) is a next-generation base station (New Radio Node B, hereinafter NR gNB or NR base station) (1c-10) and NR CN (1c). -05, New Radio Core Network). The user terminal (New Radio User Equipment, hereinafter NR UE or terminal) 1c-15 accesses the external network through the NR gNB 1c-10 and NR CN 1c-05.

In FIG. 1C, the NR gNB 1c-10 corresponds to an Evolved Node B (eNB) of an existing LTE system. The NR gNB is connected to the NR UE 1c-15 through a radio channel and can provide a service superior to that of the existing Node B. In the next-generation mobile communication system, all user traffic is serviced through a shared channel, so a device that collects and schedules status information such as buffer status, available transmission power status, and channel status of UEs is required. (1c-10) is in charge. One NR gNB typically controls multiple cells. In order to implement ultra-high-speed data transmission compared to the current LTE, it may have more than the existing maximum bandwidth, and a beamforming technology may be additionally grafted by using Orthogonal Frequency Division Multiplexing (OFDM) as a wireless access technology. . In addition, an adaptive modulation and coding method (hereinafter referred to as AMC) that determines a modulation scheme and a channel coding rate according to the channel state of the terminal is applied. The NR CN (1c-05) performs functions such as mobility support, bearer setup, and QoS setup. The NR CN is a device responsible for various control functions as well as mobility management functions for a terminal, and is connected to a plurality of base stations. In addition, the next-generation mobile communication system can be interlocked with the existing LTE system, and the NR CN is connected to the MME (1c-25) through a network interface. The MME is connected to the existing eNB (1c-30).

1D is a diagram showing a radio protocol structure of a next-generation mobile communication system to which the present invention can be applied. .

Referring to Figure 1d, the radio protocol of the next-generation mobile communication system is NR SDAP (1d-01, 1d-45), NR PDCP (1d-05, 1d-40), NR RLC (1d-10) in the terminal and the NR base station, respectively. , 1d-35), and NR MAC (1d-15, 1d-30).

The main functions of the NR SDAP (1d-01, 1d-45) may include some of the following functions.

-Transfer of user plane data

-Mapping between a QoS flow and a DRB for both DL and UL for uplink and downlink

-Marking QoS flow ID for uplink and downlink (marking QoS flow ID in both DL and UL packets)

-A function of mapping a relective QoS flow to a data bearer for uplink SDAP PDUs (reflective QoS flow to DRB mapping for the UL SDAP PDUs).

For the SDAP layer device, the UE may be configured with an RRC message to set whether to use the header of the SDAP layer device or the function of the SDAP layer device for each PDCP layer device, bearer or logical channel, and the SDAP header. If is set, the UE uses the NAS QoS reflective configuration 1-bit indicator (NAS reflective QoS) in the SDAP header and the AS QoS reflective configuration 1-bit indicator (AS reflective QoS) to map the QoS flow and data bearer of the uplink and downlink. Can be instructed to update or reset. The SDAP header may include QoS flow ID information indicating QoS. The QoS information may be used as data processing priority, scheduling information, etc. to support smooth service.

The main functions of NR PDCP (1d-05, 1d-40) may include some of the following functions.

Header compression and decompression (ROHC only)

-Transfer of user data

-In-sequence delivery of upper layer PDUs

-Out-of-sequence delivery of upper layer PDUs

-Order reordering function (PDCP PDU reordering for reception)

-Duplicate detection of lower layer SDUs

-Retransmission of PDCP SDUs

-Encryption and decryption function (Ciphering and deciphering)

-Timer-based SDU discard in uplink.

In the above, the reordering function of the NR PDCP device refers to a function of rearranging the PDCP PDUs received from the lower layer in order based on the PDCP sequence number (SN), and the function of delivering data to the upper layer in the rearranged order. It may include, or may include a function of immediately delivering without considering the order, may include a function of recording lost PDCP PDUs by rearranging the order, and reporting the status of lost PDCP PDUs It may include a function of performing the transmission side, and may include a function of requesting retransmission of lost PDCP PDUs.

The main functions of the NR RLC (1d-10, 1d-35) may include some of the following functions.

-Data transfer function (Transfer of upper layer PDUs)

-In-sequence delivery of upper layer PDUs

-Out-of-sequence delivery of upper layer PDUs

-ARQ function (Error Correction through ARQ)

-Concatenation, segmentation and reassembly of RLC SDUs

-Re-segmentation of RLC data PDUs

-Reordering of RLC data PDUs

-Duplicate detection

-Protocol error detection

-RLC SDU discard function (RLC SDU discard)

-RLC re-establishment

In the above, the in-sequence delivery function of the NR RLC device refers to the function of delivering RLC SDUs received from the lower layer to the upper layer in order, and originally, one RLC SDU is divided into several RLC SDUs and received. If so, it may include a function of reassembling and delivering it, and may include a function of rearranging the received RLC PDUs based on RLC sequence number (SN) or PDCP sequence number (SN), and rearranging the order It may include a function of recording lost RLC PDUs, may include a function of reporting a status of lost RLC PDUs to a transmitting side, and a function of requesting retransmission of lost RLC PDUs. If there is a lost RLC SDU, it may include a function of transferring only RLC SDUs before the lost RLC SDU to a higher layer in order, or if a predetermined timer expires even if there is a lost RLC SDU, the timer It may include a function of delivering all RLC SDUs received before the start of the system in order to the upper layer, or if a predetermined timer expires even if there is a lost RLC SDU, all RLC SDUs received so far are sequentially transferred to the upper layer. It may include the ability to deliver. In addition, RLC PDUs may be processed in the order in which they are received (regardless of the order of serial number and sequence number, in the order of arrival) and delivered to the PDCP device regardless of the order (Out-of sequence delivery). Segments stored in a buffer or to be received in the future may be received, reconstructed into one complete RLC PDU, processed, and delivered to the PDCP device. The NR RLC layer may not include a concatenation function, and the function may be performed by the NR MAC layer or may be replaced with a multiplexing function of the NR MAC layer.

In the above, the out-of-sequence delivery function of the NR RLC device refers to a function of directly delivering RLC SDUs received from the lower layer to the upper layer regardless of the order, and originally, one RLC SDU is When it is divided into SDUs and received, it may include a function of reassembling and transmitting them, and includes a function of storing the RLC SN or PDCP SN of the received RLC PDUs, sorting the order, and recording the lost RLC PDUs. I can.

The NR MACs 1d-15 and 1d-30 may be connected to several NR RLC layer devices configured in one terminal, and the main functions of the NR MAC may include some of the following functions.

-Mapping between logical channels and transport channels

-Multiplexing and demultiplexing function (Multiplexing/demultiplexing of MAC SDUs)

-Scheduling information reporting function

-HARQ function (Error correction through HARQ)

-Priority handling between logical channels of one UE

-Priority handling between UEs by means of dynamic scheduling

-MBMS service identification

-Transport format selection

-Padding function

The NR PHY layer (1d-20, 1d-25) channel-codes and modulates upper layer data, converts it into OFDM symbols, and transmits it to the radio channel, or demodulates and channel-decodes OFDM symbols received through the radio channel to the upper layer. You can perform the transfer operation.

In the present invention, a bearer may mean including SRB and DRB, SRB means Signaling Radio Bearer, and DRB means Data Radio Bearer. In addition, UM DRB refers to a DRB using an RLC layer device operating in an UM (Unacknowledged Mode) mode, and AM DRB refers to a DRB using an RLC layer device operating in an AM (Acknowledged Mode) mode. In addition, SRB0 is an unencrypted SRB, which is set in the MCG of the terminal and refers to a bearer through which the base station and the terminal exchange RRC messages, and SRB1 is an encrypted SRB that is set in the MCG of the terminal, and the base station and the terminal establish a major connection. It refers to a bearer that sends and receives messages, and SRB2 is an encrypted SRB, which is set in the MCG of the terminal, and the base station and the terminal establish a connection and refer to a bearer for sending and receiving NAS-related RRC messages, and SRB3 is an encrypted SRB and the SCG of the terminal. It is set to and refers to a bearer through which the UE can directly transmit an RRC message to the MCG through the SCG MAC layer device. In the Split SRB, one PDCP layer device is in the MCG or SCG, two RLC layer devices are connected to the one PDCP layer device to perform data transmission and reception, and one RLC layer device is connected to the MCG MAC layer device. , Another RLC layer device means an SRB connected to the SCG MAC layer device.

1E shows that in the next-generation mobile communication system of the present invention, a terminal switches from an RRC idle mode or an RRC inactive mode to an RRC connected mode, and a base station is a carrier aggregation technology or dual access. A diagram showing a procedure for setting a technology to a terminal.

In FIG. 1E, the base station may transition the UE to the RRC idle mode or the RRC deactivation mode for a predetermined reason from the RRC connected mode UE that has established a connection with the network. In the above, the predetermined reason may be a shortage of scheduling resources of the base station or a suspension of data transmission/reception with the terminal for a predetermined time.

In the above, the base station may transmit an RRCRelease message to the terminal to instruct the terminal to transition to an RRC idle mode or an RRC deactivation mode. In the above, the RRCRelease message can instruct the terminal to transition to the RRC deactivation mode with an indicator (suspend-config), and if the indicator (suspend-config) is not included in the RRCRelease message, the terminal can transition to the RRC idle mode. (1e-05).

When the terminal transitions to the RRC idle mode or RRC deactivation mode, if connection with the network is required for a predetermined reason, it performs a random access procedure, receives a random access response, requests RRC connection setup, and receives an RRC message to establish an RRC connection. Can be performed (1e-10, 1e-15, 1e-20, 1e-25, 1e-30, 1e-35, 1e-40).

The UE establishes uplink transmission synchronization with the base station through a random access process and transmits an RRCSetupRequest message or an RRCResumeRequest message (in the case of an RRC deactivation mode UE) to the base station (1e-25). The RRCSetupRequest message or the RRCResumeRequest message (in the case of an RRC deactivation mode terminal) may include an identifier of the terminal and a reason for establishing a connection (establishmentCause).

The base station transmits an RRCSetup message or an RRCResume message (in case of an RRC deactivation mode terminal) so that the terminal establishes an RRC connection (1e-30). In the RRCSetup message or RRCResume message (for RRC inactive mode terminals), at least one of configuration information for each logical channel, configuration information for each bearer, configuration information for a PDCP layer device, configuration information for an RLC layer device, and configuration information for a MAC layer device One can be included.

In the RRCSetup or RRCResume message (for RRC deactivation mode terminal) message, a bearer identifier (e.g., SRB identifier or DRB identifier) is allocated to each bearer, and a PDCP layer device, RLC layer device, MAC layer device for each bearer , PHY layer device configuration can be indicated.

The terminal that has set up the RRC connection transmits an RRCSetupComplete message or an RRCResumeComplete message (in the case of an RRC deactivation mode terminal) to the base station (1e-40). The RRCSetupComplete message or the RRCResumeComplete message (in the case of an RRC deactivation mode terminal) may include a control message called SERVICE REQUEST requesting the AMF or MME to set up a bearer for a predetermined service by the terminal. The base station may transmit the SERVICE REQUEST message received in the RRCConnetionSetupComplete message or the RRCResumeComplete message (in the case of an RRC deactivation mode terminal) to the AMF or MME, and the AMF or MME may determine whether to provide the service requested by the terminal.

As a result of the determination, if the terminal decides to provide the requested service, the AMF or MME transmits an INITIAL CONTEXT SETUP REQUEST message to the base station. The INITIAL CONTEXT SETUP REQUEST message may include information such as QoS (Quality of Service) information to be applied when setting up a Data Radio Bearer (DRB), and security-related information (e.g., Security Key, Security Algorithm) to be applied to the DRB.

The base station transmits and receives a SecurityModeCommand message and a SecurityModeComplete message to configure security with the terminal, and when security configuration is completed, the base station transmits an RRCConnectionReconfiguration message to the terminal (1e-45).

In the RRCConnectionReconfiguration message, a bearer identifier (for example, an SRB identifier or a DRB identifier) is allocated to each bearer, and a PDCP layer device, an RLC layer device, a MAC layer device, and a PHY layer device can be configured for each bearer.

In addition, in the RRCConnectionReconfiguration message, additional SCells may be configured to configure the frequency aggregation technology to the terminal, or additional SCG configuration information may be configured to configure the dual access technology.

In addition, the RRCConnectionReconfiguration message may include configuration information of the DRB in which user data is to be processed, and the terminal applies the information to configure the DRB and transmits an RRCConnectionReconfigurationComplete message to the base station (1e-45). After completing the DRB setup with the UE, the base station may transmit an INITIAL CONTEXT SETUP COMPLETE message to the AMF or MME and complete the connection (1e-50).

When all of the above processes are completed, the terminal transmits and receives data through the base station and the core network (1e-55, 1e-60). According to some embodiments, the data transmission process is largely composed of three steps of RRC connection setup, security setup, and DRB setup. In addition, the base station may transmit an RRC Connection Reconfiguration message to the terminal for a predetermined reason in order to refresh, add, or change the configuration (1e-65). For example, in the frequency integration technology, the setting of adding, releasing, or changing the Scell can be performed, and in the dual access technology, the SCG setting can be changed, canceled, or added.

The procedure for the base station to set the carrier aggregation technology or the dual access technology to the terminal as described above can be summarized as follows. First, when the terminal establishes a connection with the base station, and the base station sets the frequency measurement configuration information to the RRC connection mode terminal, the terminal performs frequency measurement based on the frequency measurement configuration information and reports the measurement result to the base station. In addition, the base station may set additional Scell configuration information as an RRC message to configure the carrier aggregation technology to the terminal based on the frequency measurement result of the terminal, and send MAC CE to activate, dormant or deactivate the Scells. . In addition, the base station may set additional cell group (Sceondary cell group) configuration information to set the dual access technology to the terminal based on the frequency measurement result of the terminal.

1F is a diagram showing the structure of a protocol layer apparatus of a terminal in which dual access technology is configured in the present invention.

As described in Fig. 1e, when the base station configures SCG configuration information to configure the dual access technology to the terminal, the terminal is configured with a PDCP layer device for SCG or an RLC layer device or MAC in consideration of the bearer identifier and logical identifier corresponding to the SCG. A layer device may be established as shown in FIG. 1F. Therefore, from the point of view of the terminal, the MAC layer device 1f-15 for MCG and the MAC layer device 1f-20 for SCG are set, respectively, and RLC layer devices and PDCP layer devices corresponding to each MCG or SCG are configured. I can. In addition, in the case of split SRB or split DRB, as shown in 1f-30, one PDCP layer device belongs to MCG or SCG, and two different RLC layer devices are connected to each of the MCG MAC layer device and the SCG MAC layer device. Can have a structure that is

From the standpoint of the base station, the base station corresponding to the MCG may have the same layer structure as the protocol layer device structure for the MCG of the terminal, and the base station corresponding to the SCG may have the same layer structure as the protocol layer device structure for the SCG of the terminal. I can.

In the first embodiment of the present invention, consider a case in which the MCG maintains a connection with a base station (or cell) in a terminal configured with dual access technology as shown in FIG. 1F, and a wireless connection failure with the base station (or cell) occurs in the SCG. .

In the above, the wireless connection failure of the SCG may be determined as a wireless connection failure due to one of the following reasons.

1.When the SCG physical (PHY) layer device indicates to the RRC layer device that the signal is not synchronized, and thus a timer (eg, T310) is started in the Pscell, and the timer expires,

2. In case of integrity verification failure in SRB3,

3. When it is indicated to the RRC layer device that a random access problem has occurred in the SCG MAC layer device while certain timers (for example, T300 or T301 or T304 or T311 or T319) are not driven,

4. In the AM RLC layer device connected to the SCG MAC layer device, the number of retransmissions has reached the maximum number of retransmissions, the RLC layer device is not set to a packet redundancy technology (set to a carrier aggregation technology or dual access technology), and the RLC layer When mapping (allowedServingCell) for transmission/reception for the logical channel corresponding to the device is set only for Scell,

If, for one of the above reasons, the MCG is connected to the base station (or cell) in the terminal with dual access technology configured, but a wireless connection failure occurs with the base station (or cell) in the SCG, the terminal transmits data in the MCG. In order to continuously transmit/receive, recover the SCG, change to another SCG, or release the SCG in which the radio failure has occurred, the following terminal operation is proposed. In addition, if a wireless connection failure is detected when data transmission/reception through the SCG is not stopped, the UE may perform the following operation.

-If the RRC layer device is instructed that the signal is not synchronized in the SCG physical (PHY) layer device, and the timer (eg, T310) is started in the Pscell, the timer expires.

-If it is indicated to the RRC layer device that a random access problem has occurred in the SCG MAC layer device while certain timers (for example, T300 or T301 or T304 or T311 or T319) are not running

-If integrity verification failure occurs in SRB3

-If the number of retransmissions reaches the maximum number of retransmissions in the AM RLC layer device connected to the SCG MAC layer device

■ When mapping for transmission/reception (allowedServingCell) for the logical channel corresponding to the RLC layer device is set only in Scell

◆ The terminal does not determine that the SCG radio failure has occurred, and transmits failure information to the base station to report that the RLC layer device has failed. Specifically, the failure information may include an indicator indicating which cell group the RLC layer device belongs to (MCG or SCG), a logical channel identifier, and a type of failure (for example, reaching the maximum number of retransmissions), and the RLC When the layer device fails in the RLC layer device connected to the SCG MAC layer device, if the terminal is configured with dual access technology as an LTE base station and an NR base station or an NR base station and an NR base station, and SRB3 (or split SRB) is configured The UE may report the failure of the SCG RLC layer device to the MCG base station in SRB3 (or split SRB). If dual access technology is not configured or SRB3 (or split SRB) is not configured, the UE may indicate to the base station by including the failure information in the RRC message in the MCG MAC layer device. In addition, the failure information may include measurement results for other frequencies so that the base station can use it to quickly set up a new Scell or a new SCG.

■ When mapping (allowedServingCell) for transmission/reception for the logical channel corresponding to the RLC layer device is not set only in Scell, or in other cases

◆ Consider that the SCG has encountered a radio link failure (RLF).

◆ And the terminal reports the SCG radio connection failure to the base station. In detail, since the UE detects the SCG radio connection failure, the transmission to the SCG base station is stopped for all SRBs or DRBs configured. And the SCG MAC layer device is initialized. Then, if the T304 timer (a timer driven in case of handover) is running, it is stopped (for example, in case of SCG change during handover, because SCG radio failure can be detected). In addition, SCG radio connection failure type (e.g., RLC maximum number of retransmissions exceeded, integrity verification failure, synchronization out of synchronization, timer expiration, etc.) is indicated, and SCG radio failure message is constructed, and the SCG through the SRB connected to the MCG MAC layer device. The wireless connection failure can be reported to the MCG base station. In addition, the failure information may include measurement results for other frequencies so that the base station can use it to quickly set up a new Scell or a new SCG.

As suggested above, in the terminal with dual access technology configured, the MCG maintains a connection with the base station (or cell), but if a wireless connection failure occurs with the base station (or cell) in the SCG, the terminal continues to transmit and receive data in the MCG. In order to allow the base station to recover the SCG, change the SCG to another SCG, or release the SCG in which the radio failure has occurred, the terminal may report a wireless connection failure of the SCG to the MCG base station, thereby enabling continuous data transmission.

In the above, when the MCG base station receives a report of the wireless connection failure of the SCG, the SRB connected to the MCG MAC layer device of the terminal (e.g., SRB1 or SRB2 ) Through the RRC message can be transmitted. Specifically, it may be instructed to release the existing SCG configuration information, or it may transmit new SCG configuration information, inform the random access information to be used in the random access procedure, and establish a connection to the new SCG, or reconnect to the existing SCG. It can also inform you of random access information to be used in the random access procedure to try.

In the second embodiment of the present invention, consider a case in which the SCG maintains a connection with a base station (or cell) in a terminal configured with dual access technology as shown in FIG. 1F, and a wireless connection failure occurs with the base station (or cell) in the MCG. .

In the above, the wireless connection failure of the MCG may be determined as a wireless connection failure due to one of the following reasons.

1.When the RRC layer device is instructed that the signal is not synchronized in the MCG physical (PHY) layer device and a timer (for example, T310) is started in the Pcell, and the timer expires,

2. In case of integrity verification failure in SRB1 or SRB2,

3. When it is indicated to the RRC layer device that a random access problem has occurred in the MCG MAC layer device while certain timers (for example, T300 or T301 or T304 or T311 or T319) are not driven,

4. In the AM RLC layer device connected to the MCG MAC layer device, the number of retransmissions has reached the maximum number of retransmissions, the RLC layer device is not set to a packet redundancy technology (set to a carrier aggregation technology or dual access technology), and the RLC layer When mapping (allowedServingCell) for transmission/reception for the logical channel corresponding to the device is set only for Scell,

If, for one of the above reasons, the SCG is connected to the base station (or cell) in the UE configured with dual access technology, but a wireless connection failure occurs with the base station (or cell) in the MCG, the UE transmits data in the SCG. A terminal operation is proposed as follows in order to continuously transmit/receive, recover the MCG, change to another MCG, release the MCG in which the radio failure has occurred, or switch the SCG for which the current connection is maintained to the MCG. In addition, if a wireless connection failure is detected when data transmission/reception through the MCG is not stopped, the UE may perform the following operation.

-If the RRC layer device is instructed that the signal is not synchronized in the MCG physical (PHY) layer device and a timer (for example, T310) is started in the Pcell, and the timer has expired

-If it is indicated to the RRC layer device that a random access problem has occurred in the MCG MAC layer device while certain timers (for example, T300 or T301 or T304 or T311 or T319) are not running

-If integrity verification failure occurs in SRB1 or SRB2

-If the number of retransmissions reaches the maximum number of retransmissions in the AM RLC layer device connected to the MCG MAC layer device

■ When mapping for transmission/reception (allowedServingCell) for the logical channel corresponding to the RLC layer device is set only in Scell

◆ The terminal does not determine that the MCG radio failure has occurred, and transmits failure information to the base station to report that the RLC layer device has failed. Specifically, the failure information may include an indicator indicating which cell group the RLC layer device belongs to (MCG or SCG), a logical channel identifier, and a type of failure (for example, reaching the maximum number of retransmissions), and the RLC When a failure occurs in the RLC layer device connected to the MCG MAC layer device, the UE may indicate to the base station by transmitting the failure information to SRB1 in the RRC message from the MCG MAC layer device. In addition, the failure information may include measurement results for other frequencies so that the base station can use it to quickly set up a new Scell or a new SCG.

■ When mapping (allowedServingCell) for transmission/reception for the logical channel corresponding to the RLC layer device is not set only in Scell, or in other cases

◆ Consider that the MCG has a radio link failure (RLF).

◆ If the AS security setting is not activated (a connection failure occurs during RRC connection establishment) or when the AS security setting is activated but at least one DRB with SRB2 is not established (complete RRC connection is not established). The terminal transitions to the RRC idle mode.

◆ If not above

● If dual access technology is set for the terminal, the SCG is not stopped, data transmission and reception is possible, and the MCG MAC layer device and the SCG MAC layer device of the terminal are connected to the MCG base station (the MCG has a PDCP layer device). If the SRB (e.g., SRB3) connected to the SCG MAC layer device connected to the split SRB (for example, split SRB1) or the SCG base station (SCG has a PDCP layer device) is configured in the UE, one of the following methods One way can be done.

■ Method 1: The terminal may report the MCG radio connection failure to the MCG base station or the SCG base station (if it is reported to the SCG base station, the SCG base station may inform the MCG base station of the MCG radio connection failure of the terminal). In detail, since the UE detects an MCG radio connection failure, all SRBs or DRBs set in the set MCG are stopped transmitting to the MCG base station. Then, the MCG MAC layer device is initialized. However, bearers or layer devices set in the SCG are characterized in that they are not initialized and can be maintained and data transmission/reception can continue. Then, if the T304 timer (a timer that is activated in case of handover) is running, it stops (since a radio failure can be detected during handover). In addition, a split SRB connected to the SCG MAC layer device by indicating the type of MCG wireless connection failure (e.g., exceeding the maximum number of RLC retransmissions, or failing to verify integrity, or out of synchronization, or expiring a timer, etc.), and configuring an MCG radio failure message. For example, the MCG radio connection failure may be reported to the MCG base station or the SCG base station through the split SRB1) or the SRB connected to the SCG MAC layer device (for example, SRB3). In addition, the failure information may include measurement results for other frequencies so that the base station can use it to quickly set up a new cell (eg, Pcell) or a new cell group (eg, MCG). In addition, the reason for the failure may be indicated in the wireless connection failure information. Method 1 is a method in which the UE instructs MCG failure information so that the base station can recover or change the MCG in which the radio failure is indicated, and is a method for solving based on the MCG or SCG base station.

■ Method 2: The UE stops transmission to the MCG base station for all SRBs or DRBs except for SRB0 because it has detected an MCG radio connection failure (SRB0 has to transmit an RRC re-establishment message, so if the transmission is stopped, Can not be done). Then, the MCG MAC layer device is initialized. However, bearers or layer devices set in the SCG are characterized in that they are not initialized and can be maintained and data transmission/reception can continue. Then, if the T304 timer (a timer that is activated in case of handover) is running, it stops (since a radio failure can be detected during handover). The terminal may trigger an RRC connection reestablishment procedure for the MCG base station, and when transmitting an RRC connection reestablishment request message in the procedure, it may indicate that an MCG radio connection failure has occurred. . In addition, the reason for the failure may be indicated in the wireless connection failure information. Method 2 is a method in which the terminal checks the MCG failure information and allows the terminal to resolve itself.

■ Method 3: The terminal stops transmission to the MCG base station for all SRBs or DRBs set because it detects the MCG radio connection failure. Then, the MCG MAC layer device is initialized. However, bearers or layer devices set in the SCG are characterized in that they are not initialized and can be maintained and data transmission/reception can continue. Then, if the T304 timer (a timer that is activated in case of handover) is running, it stops (since a radio failure can be detected during handover). The terminal may report the MCG radio connection failure to the MCG base station or the SCG base station (when reporting to the SCG base station, the SCG base station may inform the MCG base station of the MCG radio connection failure of the terminal). Specifically, the terminal may trigger an RRC connection reestablishment procedure for the MCG base station or the SCG base station, and when transmitting an RRC connection reestablishment request message in the above procedure, the MCG radio connection failure occurred. It can be indicated to the MCG base station or the SCG base station. In the above procedure, when transmitting the RRC connection re-establishment request message, it indicates that the MCG radio connection failure has occurred. Split SRB connected to the SCG MAC layer device (e.g., split SRB1) or SRB connected to the SCG MAC layer device (for example, SRB3 or SRB0) can be indicated. In addition, the reason for the failure may be indicated in the wireless connection failure information. Method 3 is a method in which the terminal instructs the MCG failure information to be split SRB1 or SRB3 so that the base station can recover or change the MCG in which the radio failure is indicated, and is a method for solving based on the MCG base station or the SCG base station.

■ Method 4: Since the UE detects the MCG radio connection failure, it stops the transmission to the MCG base station for all SRBs or DRBs except for the configured SRB0 (SRB0 has to transmit an RRC re-establishment message, so if the transmission is stopped, Can not be done). Then, the MCG MAC layer device is initialized. However, bearers or layer devices set in the SCG are characterized in that they are not initialized and can be maintained and data transmission/reception can continue. Then, if the T304 timer (a timer that is activated in case of handover) is running, it stops (since a radio failure can be detected during handover). The terminal may report the MCG radio connection failure to the MCG base station or the SCG base station (when reporting to the SCG base station, the SCG base station may inform the MCG base station of the MCG radio connection failure of the terminal). Specifically, the terminal can trigger an RRC connection reestablishment procedure for an MCG base station or an SCG base station, that is, after camping on a cell having a good signal through a cell reselection procedure, an RRC connection through SRB0 The re-establishment request message is transmitted, and the MCG base station or the SCG base station may be indicated that the MCG radio connection failure has occurred using an indicator. In addition, the reason for the failure may be indicated in the wireless connection failure information. Method 4 is a method in which the UE instructs the MCG failure information to SRB0 so that the base station can recover or change the MCG in which the radio failure is indicated, so that the MCG base station or the SCG base station can resolve it.

● If the dual access technology is not configured in the terminal, the SCG transmission is stopped, data transmission/reception is impossible, and the split SRB (for example, split SRB1) connected to the SCG base station or the SRB is not configured in the terminal, or other If it is the case

■ The UE stops transmission to the MCG base station for all SRBs or DRBs except for the configured SRB0 because the MCG radio connection failure is detected (SRB0 must not stop the transmission because the RRC re-establishment message must be transmitted). Then, the MCG MAC layer device is initialized. In addition, it is characterized in that all bearers (SRB or DRB) set in the SCG are stopped and the SCG MAC layer device is also initialized, and the SCG bearers and SCG configuration information are released. Then, if the T304 timer (a timer that is activated in case of handover) is running, it stops (since a radio failure can be detected during handover). The terminal may report the MCG radio connection failure to the MCG base station or the SCG base station (when reporting to the SCG base station, the SCG base station may inform the MCG base station of the MCG radio connection failure of the terminal). Specifically, the terminal can trigger an RRC connection reestablishment procedure for an MCG base station or an SCG base station, that is, after camping on a cell having a good signal through a cell reselection procedure, an RRC connection through SRB0 The re-establishment request message is transmitted, and the MCG base station or the SCG base station may be indicated that the MCG radio connection failure has occurred using an indicator. In addition, the reason for the failure may be indicated in the wireless connection failure information.

As suggested above, in the UE configured with dual access technology, the SCG maintains connection with the base station (or cell), but if a wireless connection failure occurs with the base station (or cell) in the MCG, the UE continues to transmit and receive data in the SCG. , The base station recovers the MCG, releases the MCG in which the radio failure has occurred, and adds a new cell group to change the use of the MCG, or changes the role of the SCG for which the current wireless connection is maintained to the MCG. By having the base station or the SCG base station report a wireless connection failure of the MCG, continuous data transmission can be possible.

In the above, when the MCG base station, the SCG base station, or the new base station (when the RRC connection re-establishment procedure is performed with the new base station after cell reselection) receives a report of the radio connection failure of the MCG, it recovers the MCG of the terminal or the MCG in which the radio failure occurs. The split SRB connected to the SCG MAC layer device of the UE (e.g., split SRB1) so that the SCG for which the current wireless connection is maintained can be changed to MCG and used as MCG by canceling and adding a new cell group. Or split SRB2) or an SRB (eg, SRB3) connected to the SCG MAC layer device, or through SRB0 connected to the MCG MAC layer device, configuration information may be transmitted as an RRC message. Specifically, it can be instructed to release the existing MCG setting information, or it can transmit new cell group setting information, inform the random access information to be used in the random access procedure, establish a connection to the new cell group, and instruct to use it as an MCG. Alternatively, random access information to be used in the random access procedure may be provided to attempt to reconnect to the existing MCG. As another method, the base station configures the information in the RRC message indicating that the terminal can consider the SCG configuration information previously set to the terminal to be regarded as MCG, and the split SRB connected to the MCG MAC layer device of the terminal (e.g., split SRB1 Or split SRB2) or an SRB (for example, SRB3) connected to an SCG MAC layer device, or SRB0 connected to an MCG MAC layer device. Therefore, a cell that used to be a Pscell may be considered a Pcell, and when the role of the existing SCG is changed to an MCG, the base station may configure the dual access technology again by setting another cell group to be added as an SCG.

1G is a diagram showing the structure of a protocol layer apparatus of a terminal in which a frequency aggregation technology is configured in the present invention.

As described in Fig. 1e, when the base station configures Scell configuration information, bearer configuration information, and protocol layer device configuration information to set the carrier aggregation technology to the UE, the UE may use the PDCP layer device or the RLC layer device or MAC A layer device may be established as shown in FIG. 1G. Accordingly, the terminal may set the MAC layer device 1g-15 for the Pcell 1g-01 and the plurality of Scells 1g-02 and 1g-03. The MAC layer device divides a plurality of RLC layer devices connected to the MAC layer device with a logical channel identifier, multiplexes data received from the plurality of RLC layer devices, configures one data, and performs transmission to PCells or Scells. can do. From the standpoint of the base station, the same layer structure as the protocol layer structure of the terminal may be set.

In the third embodiment of the present invention, a case in which the Scell is connected to the base station (or cell) in a terminal in which the frequency aggregation technology is configured is maintained, and a wireless connection failure with the base station (or cell) occurs in the Pcell is considered.

In the above, the wireless connection failure of the Pcell may be determined as a wireless connection failure due to one of the following reasons.

1.When the RRC layer device is instructed that the signal is not synchronized in the MCG physical (PHY) layer device and a timer (for example, T310) is started in the Pcell, and the timer expires,

2. In case of integrity verification failure in SRB1 or SRB2,

3. When it is indicated to the RRC layer device that a random access problem has occurred in the MCG MAC layer device while certain timers (for example, T300 or T301 or T304 or T311 or T319) are not driven,

4. In the AM RLC layer device connected to the MCG MAC layer device, the number of retransmissions has reached the maximum number of retransmissions, the RLC layer device is not set to a packet redundancy technology (set to a carrier aggregation technology or dual access technology), and the RLC layer When mapping (allowedServingCell) for transmission/reception for the logical channel corresponding to the device is set only for Scell,

If, for one of the above reasons, the Scell is connected to the base station (or cell) in the terminal for which the carrier aggregation technology is configured, but a wireless connection failure occurs with the base station (or cell) in the Pcell, the terminal transmits data in the Scell. In order to continuously transmit/receive, recover the Pcell, change to another Pcell, release the Pcell in which the radio failure has occurred, or switch the Scell whose current connection is maintained to the Pcell, we propose a specific terminal operation in the following. In order to be able to report or indicate a wireless connection failure of a Pcell through the Scell proposed in the present invention, an Scell that satisfies a plurality of conditions among the following conditions must be set to the UE. That is, the wireless connection failure report of the Pcell is possible only for Scells that satisfy a plurality of conditions among the following conditions.

-First condition: Scell must be set as a separate timing adjustment group (sTAG) that is distinct from Pcell. This is because if the Scell is set to the timing adjustment group (pTAG) of the Pcell, a wireless connection failure of the Pcell occurs, and thus the Scell referring to the PCell may similarly cause a wireless connection failure.

-Second condition: Scell must have both uplink and downlink configured. This is because the uplink must be configured to report a connection failure of the Pcell, and additional configuration information must be received through the downlink.

-Third condition: Scell must be configured with PUCCH. PUCCH must be configured to report a connection failure of a Pcell or to indicate HARQ ACK/NACK information or to report a PHR after receiving an additional configuration information message.

-Fourth condition: Scell must be activated. This is because data transmission and reception can be performed on the uplink and downlink only when the Scell is activated.

-The fifth condition: The activated BWP (Bandwidth Part) must be set in the Scell, and there may be an SSB in the activated BWP in order to synchronize the signal.

-Sixth condition: When the base station sets cell configuration information with an RRC message as shown in Fig. 1e of the present invention, the base station indicates specific SCells using an indicator, and in MCG (or PCell) or SCG (or PSCell) When a connection failure occurs, specific SCells capable of reporting an MCG (or PCell) or SCG (or PSCell) connection failure may be indicated.

In the third embodiment of the present invention, in a terminal configured with a carrier aggregation technology, the Scell maintains a connection with the base station (or cell), but if a wireless connection failure occurs with the base station (or cell) in the Pcell, the terminal transmits data in the Scell. A specific terminal that reports a wireless connection failure of a PCell to a specific Scell so that it can continuously transmit/receive, restore a Pcell, change to another Pcell, release a Pcell in which the wireless failure has occurred, or convert a Scell with a current connection to a Pcell. Suggest an action.

-If the RRC layer device is instructed that the signal is not synchronized in the MCG physical (PHY) layer device and a timer (for example, T310) is started in the Pcell, and the timer has expired

-If it is indicated to the RRC layer device that a random access problem has occurred in the MCG MAC layer device while certain timers (for example, T300 or T301 or T304 or T311 or T319) are not running

-If integrity verification failure occurs in SRB1 or SRB2

-If the number of retransmissions reaches the maximum number of retransmissions in the AM RLC layer device connected to the MCG MAC layer device

■ When mapping for transmission/reception (allowedServingCell) for the logical channel corresponding to the RLC layer device is set only in Scell

◆ The terminal does not determine that the MCG radio failure has occurred, and transmits failure information to the base station to report that the RLC layer device has failed. Specifically, the failure information may include an indicator indicating which cell group the RLC layer device belongs to (MCG or SCG), a logical channel identifier, and a type of failure (for example, reaching the maximum number of retransmissions), and the RLC When a failure occurs in the RLC layer device connected to the MCG MAC layer device, the UE may indicate to the base station by transmitting the failure information to SRB1 in the RRC message from the MCG MAC layer device. In addition, the failure information may include measurement results for other frequencies so that the base station can use it to quickly set up a new Scell or a new SCG.

■ When mapping (allowedServingCell) for transmission/reception for the logical channel corresponding to the RLC layer device is not set only in Scell, or in other cases

◆ Consider that the MCG has a radio link failure (RLF).

◆ If the AS security setting is not activated (a connection failure occurs during RRC connection establishment) or when the AS security setting is activated but at least one DRB with SRB2 is not established (complete RRC connection is not established). The terminal transitions to the RRC idle mode.

◆ If not above

● If a carrier aggregation technology is set for the terminal, and among the configured Scells, Scells that satisfy the first condition, the second condition, the third condition, the fourth condition, the fifth condition, or the sixth condition If it is set

■ The terminal may report a wireless connection failure of the Pcell through the Scell. Specifically, the UE configures an RRC message for Pcell radio connection failure information, configures the information as data in the MCG MAC layer device through the SRB1 or SRB2 bearer, that is, the logical channel identifier corresponding to SRB1 or SRB2, and configures the plurality of conditions. With a satisfactory Scell, information about a wireless connection failure of the Pcell can be transmitted to the base station.

● If the terminal does not have a carrier aggregation technology, or among the configured Scells, the first condition, the second condition, the third condition, the fourth condition, the fifth condition, or the sixth condition is satisfied. If Scell is not set

■ If the dual access technology is set for the terminal, the SCG is not stopped, data transmission and reception is possible, and the MCG MAC layer device and the SCG MAC layer device of the terminal are connected to the MCG base station (the MCG has a PDCP layer device) If the SRB (e.g., SRB3) connected to the SCG MAC layer device connected to the split SRB (for example, split SRB1) or the SCG base station (SCG has a PDCP layer device) is configured in the UE, one of the following methods One way can be done.

◆ Method 1: The terminal may report the MCG radio connection failure to the MCG base station or the SCG base station (if it is reported to the SCG base station, the SCG base station may inform the MCG base station of the MCG radio connection failure of the terminal). In detail, since the UE detects an MCG radio connection failure, all SRBs or DRBs set in the set MCG are stopped transmitting to the MCG base station. Then, the MCG MAC layer device is initialized. However, bearers or layer devices set in the SCG are characterized in that they are not initialized and can be maintained and data transmission/reception can continue. Then, if the T304 timer (a timer that is activated in case of handover) is running, it stops (since a radio failure can be detected during handover). In addition, a split SRB connected to the SCG MAC layer device by indicating the type of MCG wireless connection failure (e.g., exceeding the maximum number of RLC retransmissions, or failing to verify integrity, or out of synchronization, or expiring a timer, etc.), and configuring an MCG radio failure message. For example, the MCG radio connection failure may be reported to the MCG base station or the SCG base station through the split SRB1) or the SRB connected to the SCG MAC layer device (for example, SRB3). In addition, the failure information may include measurement results for other frequencies so that the base station can use it to quickly set up a new cell (eg, Pcell) or a new cell group (eg, MCG). In addition, the reason for the failure may be indicated in the wireless connection failure information. Method 1 is a method in which the UE instructs MCG failure information so that the base station can recover or change the MCG in which the radio failure is indicated.

◆ Method 2: The UE stops transmission to the MCG base station for all SRBs or DRBs except for SRB0 because it has detected an MCG radio connection failure (SRB0 has to transmit an RRC re-establishment message. Can not be done). Then, the MCG MAC layer device is initialized. However, bearers or layer devices set in the SCG are characterized in that they are not initialized and can be maintained and data transmission/reception can continue. Then, if the T304 timer (a timer that is activated in case of handover) is running, it stops (since a radio failure can be detected during handover). The terminal may trigger an RRC connection reestablishment procedure for the MCG base station, and when transmitting an RRC connection reestablishment request message in the procedure, it may indicate that an MCG radio connection failure has occurred. . In addition, the reason for the failure may be indicated in the wireless connection failure information. Method 2 is a method in which the terminal checks the MCG failure information and allows the terminal to resolve itself.

◆ Method 3: Since the UE detects an MCG radio connection failure, it stops transmission to the MCG base station for all configured SRBs or DRBs. Then, the MCG MAC layer device is initialized. However, bearers or layer devices set in the SCG are characterized in that they are not initialized and can be maintained and data transmission/reception can continue. Then, if the T304 timer (a timer that is activated when handover) is running, it stops (because a radio failure can be detected during handover). The terminal may report the MCG radio connection failure to the MCG base station or the SCG base station (when reporting to the SCG base station, the SCG base station may inform the MCG base station of the MCG radio connection failure of the terminal). Specifically, the terminal may trigger an RRC connection reestablishment procedure for the MCG base station or the SCG base station, and when transmitting an RRC connection reestablishment request message in the above procedure, the MCG radio connection failure occurred. It can be indicated to the MCG base station or the SCG base station. In the above procedure, when transmitting the RRC connection re-establishment request message, it indicates that the MCG radio connection failure has occurred. Split SRB connected to the SCG MAC layer device (e.g., split SRB1) or SRB connected to the SCG MAC layer device (for example, SRB3 or SRB0) can be indicated. In addition, the reason for the failure may be indicated in the wireless connection failure information. Method 3 is a method in which the terminal instructs the MCG failure information to be split SRB1 or SRB3 so that the base station can recover or change the MCG in which the radio failure is indicated, and is a method for solving based on the MCG base station or the SCG base station.

◆ Method 4: Since the UE detects the MCG radio connection failure, it stops the transmission to the MCG base station for all SRBs or DRBs except for the configured SRB0 (SRB0 has to transmit an RRC re-establishment message. Can not be done). Then, the MCG MAC layer device is initialized. However, bearers or layer devices set in the SCG are characterized in that they are not initialized and can be maintained and data transmission/reception can continue. Then, if the T304 timer (a timer that is activated in case of handover) is running, it stops (since a radio failure can be detected during handover). The terminal may report the MCG radio connection failure to the MCG base station or the SCG base station (when reporting to the SCG base station, the SCG base station may inform the MCG base station of the MCG radio connection failure of the terminal). Specifically, the terminal can trigger an RRC connection reestablishment procedure for an MCG base station or an SCG base station, that is, after camping on a cell having a good signal through a cell reselection procedure, an RRC connection through SRB0 The re-establishment request message is transmitted, and the MCG base station or the SCG base station may be indicated that the MCG radio connection failure has occurred using an indicator. In addition, the reason for the failure may be indicated in the wireless connection failure information. Method 4 is a method in which the UE instructs the MCG failure information to SRB0 so that the base station can recover or change the MCG in which the radio failure is indicated, so that the MCG base station or the SCG base station can resolve it.

■ If the dual access technology is not configured in the terminal, the SCG is stopped, data transmission/reception is impossible, and the split SRB (eg split SRB1) or SRB connected to the SCG base station is not configured in the terminal or other If it is the case

◆ The UE stops transmission to the MCG base station for all SRBs or DRBs except for the configured SRB0 because the MCG radio connection failure is detected (SRB0 must not stop the transmission because it must transmit an RRC re-establishment message). Then, the MCG MAC layer device is initialized. In addition, it is characterized in that all bearers (SRB or DRB) set in the SCG are stopped and the SCG MAC layer device is also initialized, and the SCG bearers and SCG configuration information are released. Then, if the T304 timer (a timer that is activated in case of handover) is running, it stops (since a radio failure can be detected during handover). The terminal may report the MCG radio connection failure to the MCG base station or the SCG base station (when reporting to the SCG base station, the SCG base station may inform the MCG base station of the MCG radio connection failure of the terminal). Specifically, the terminal can trigger an RRC connection reestablishment procedure for an MCG base station or an SCG base station, that is, after camping on a cell having a good signal through a cell reselection procedure, an RRC connection through SRB0 The re-establishment request message is transmitted, and the MCG base station or the SCG base station may be indicated that the MCG radio connection failure has occurred using an indicator. In addition, the reason for the failure may be indicated in the wireless connection failure information.

As suggested above, in the terminal in which the carrier aggregation technology is configured, the Scell maintains connection with the base station (or cell), but if a wireless connection failure occurs with the base station (or cell) in the Pcell, the terminal continuously transmits and receives data from the Scells. And, the base station restores the Pcell, releases the Pcell in which the radio failure has occurred, and adds a new cell to be used as a Pcell, or the Scell that satisfies the plurality of conditions among the Scells for which the current wireless connection is maintained acts as a Pcell. In order to be able to change and use, continuous data transmission may be possible by allowing the terminal to report the wireless connection failure of the Pcell to the MCG base station through the Scell that satisfies the plurality of conditions.

In the above, when the MCG base station receives a report of the wireless connection failure of the Pcell, it recovers the Pcell of the terminal, releases the Pcell in which the wireless failure has occurred, and adds a new cell to be used as a Pcell, or among Scells for which the current wireless connection is maintained. Configuration information may be transmitted to the base station as an RRC message through the Scell satisfying the plurality of conditions so that the Scell satisfying the plurality of conditions can be used by changing its role to the Pcell. Specifically, it may be instructed to release the existing Pcell configuration information, or transmit new cell configuration information, inform random access information to be used in the random access procedure, establish a connection to a new cell, and instruct to use it as a Pcell, or The random access information to be used in the random access procedure may be informed to try to connect to the Pcell again. As another method, the base station configures the RRC message with information instructing the terminal to consider the Scell configuration information previously set to the terminal as a Pcell, and configures the Scell that satisfies a plurality of conditions connected to the MCG MAC layer device of the terminal. It can be transmitted through. Therefore, a cell that used to be an Scell can be regarded as a Pcell, and when the role of an existing Scell is changed to a Pcell, the base station can configure a carrier aggregation technology again by configuring another cell to be added as an SCell.

The above embodiments can be extended and applied even when both the frequency aggregation technology and the dual access technology are configured in the terminal.

When attempting to report an MCG radio connection failure (or Pcell connection failure) in the present invention, if both the split SRB (e.g., SRB1) and the SRB (e.g., SRB3) connected to the SCG base station are configured, the terminal uses a split SRB. Through the MCG wireless connection failure can be reported. This is because when reporting to the SRB connected to the SCG base station, the data received by the SCG base station must be re-encapsulated and transmitted to the MCG, resulting in a processing delay.

In the fourth embodiment of the present invention, if the Scell or SCG is connected to the base station (or cell) in the terminal in which the carrier aggregation technology is configured, but a wireless connection failure occurs with the base station (or cell) in the Pcell (or MCG), the terminal This Scell or SCG continues to transmit and receive data, recover Pcell (or MCG), change to another Pcell, release the Pcell in which the radio failure has occurred, or change the Scell with the current connection to Pcell. We propose a specific terminal operation that reports a wireless connection failure of the PCell to the Scell. In addition, the fourth embodiment of the present invention proposes a terminal operation in consideration of a case in which the procedure for reporting the MCG wireless connection failure (or Pcell connection failure) fails when reporting an MCG wireless connection failure (or Pcell connection failure). Specifically, when MCG wireless connection failure (or Pcell connection failure) occurs, if the first condition or the second condition or the third condition or the fourth condition or the fifth condition or the sixth condition of the present invention When the MCG radio connection failure is reported through the SCell of the MCG satisfying, a first timer may be defined and triggered. The first timer may be set as an RRC message, a timer value may also be set in an RRC message, and when triggering or transmitting the MCG radio connection failure report, the first timer may be started. In addition, if the first timer expires, an RRC message indicating a handover indicating that the MCG radio connection failure can be recovered, an RRC message indicating re-establishment of an RRC connection, an RRC message indicating disconnection of the MCG, etc. If the message is not received, it may be determined that the MCG radio connection failure reporting procedure has failed, and it may be attempted to restore the MCG radio connection by triggering the RRC connection re-establishment procedure (at this time, connection setting information for the Scell or SCG). Can also be turned off). In the RRC Connection Reestablishment procedure, the UE may attempt wireless connection to a suitable Scell selected through a cell reselection procedure, but a valid connection has already been established to prevent connection delay due to cell reselection. The RRC connection re-establishment procedure may be performed immediately with a cell supported by the existing SCG base station. As another method, if the MCG radio connection failure reporting procedure to the SCell fails, the UE may trigger the MCG radio connection failure reporting procedure again to the SCG if a dual access connection connection is established and the SCG radio connection is valid. If a wireless connection failure to the SCG is detected while the first timer is running, the UE may perform the SCG wireless connection failure reporting procedure without triggering the RRC connection re-establishment procedure immediately.

In addition, when a MCG wireless connection failure (or Pcell connection failure) occurs, if a dual connection connection is established and the SCG wireless connection is valid (e.g., there are no MCG Scells satisfying the above conditions, or the MCG wireless connection to the Scell) When a connection failure report is performed but fails, or when there is no MCG Scell, dual access technology is set and SCG is valid) The MCG radio connection failure can be reported through the SCG, and a second timer is defined and triggered. can do. The second timer may be set as an RRC message, a timer value may also be set in an RRC message, and when triggering or transmitting the MCG radio connection failure report, the second timer may be started. In addition, if the second timer expires, an RRC message indicating a handover indicating that the MCG radio connection failure can be recovered, an RRC message indicating re-establishment of an RRC connection, an RRC message indicating disconnection of the MCG, etc. If the message is not received, it may be determined that the MCG radio connection failure reporting procedure has failed, and it may be attempted to restore the MCG radio connection by triggering the RRC connection re-establishment procedure (at this time, connection setting information for the Scell or SCG). Can also be turned off). If a wireless connection failure to the SCG is detected while the second timer is running, the terminal may immediately trigger an RRC connection re-establishment procedure to attempt to restore the MCG wireless connection. In the RRC Connection Reestablishment procedure, the UE may attempt wireless connection to a suitable Scell selected through a cell reselection procedure, but a valid connection has already been established to prevent connection delay due to cell reselection. The RRC connection re-establishment procedure may be performed immediately with a cell supported by the existing SCG base station.

In the above, the first timer and the second timer may use the same timer or a previously defined timer, or may define and use separate timers, respectively.

A specific operation proposed in the fourth embodiment of the present invention is as follows.

-If the RRC layer device is instructed that the signal is not synchronized in the MCG physical (PHY) layer device and a timer (for example, T310) is started in the Pcell, and the timer has expired

-If it is indicated to the RRC layer device that a random access problem has occurred in the MCG MAC layer device while certain timers (for example, T300 or T301 or T304 or T311 or T319) are not running

-If integrity verification failure occurs in SRB1 or SRB2

-If the number of retransmissions reaches the maximum number of retransmissions in the AM RLC layer device connected to the MCG MAC layer device

■ When mapping for transmission/reception (allowedServingCell) for the logical channel corresponding to the RLC layer device is set only in Scell

◆ The terminal does not determine that the MCG radio failure has occurred, and transmits failure information to the base station to report that the RLC layer device has failed. Specifically, the failure information may include an indicator indicating which cell group the RLC layer device belongs to (MCG or SCG), a logical channel identifier, and a type of failure (for example, reaching the maximum number of retransmissions), and the RLC When a failure occurs in the RLC layer device connected to the MCG MAC layer device, the UE may indicate to the base station by transmitting the failure information to SRB1 in the RRC message from the MCG MAC layer device. In addition, the failure information may include measurement results for other frequencies so that the base station can use it to quickly set up a new Scell or a new SCG.

■ When mapping (allowedServingCell) for transmission/reception for the logical channel corresponding to the RLC layer device is not set only in Scell, or in other cases

◆ Consider that the MCG has a radio link failure (RLF).

◆ If the AS security setting is not activated (a connection failure occurs during RRC connection establishment) or when the AS security setting is activated but at least one DRB with SRB2 is not established (complete RRC connection is not established). The terminal transitions to the RRC idle mode.

◆ If not above

● If a carrier aggregation technology is set for the terminal, and among the configured Scells, Scells that satisfy the first condition, the second condition, the third condition, the fourth condition, the fifth condition, or the sixth condition Is set, and if the MCG wireless connection failure report was triggered for the first time in the Scell.

■ The terminal may report a wireless connection failure of the Pcell through the Scell. Specifically, the UE configures an RRC message for Pcell radio connection failure information, configures the information as data in the MCG MAC layer device through the SRB1 or SRB2 bearer, that is, the logical channel identifier corresponding to SRB1 or SRB2, and configures the plurality of conditions. With a satisfactory Scell, information about a wireless connection failure of the Pcell can be transmitted to the base station.

■ And you can start the 1st timer. (As described above, as a procedure for responding to the MCG radio connection failure report message, an RRC message instructing a handover instructing the base station to recover the radio connection, an RRC message instructing the RRC connection re-establishment, or the MCG disconnection When an RRC message such as an RRC message to be performed is received as a response, the first timer may be stopped or initialized.)

● If the terminal does not have a carrier aggregation technology, or among the configured Scells, the first condition, the second condition, the third condition, the fourth condition, the fifth condition, or the sixth condition is satisfied. If the Scell is not set or if the Scell has previously triggered the MCG wireless connection failure report, and the MCG wireless connection failure report procedure fails in the Scell, or the first timer has expired

■ If the dual access technology is set for the terminal, the SCG is not stopped, data transmission and reception is possible, and the MCG MAC layer device and the SCG MAC layer device of the terminal are connected to the MCG base station (the MCG has a PDCP layer device) If the SRB (e.g., SRB3) connected to the SCG MAC layer device connected to the split SRB (for example, split SRB1) or the SCG base station (SCG has a PDCP layer device) is configured in the UE, one of the following methods One way can be done.

◆ Method 1: The terminal may report the MCG radio connection failure to the MCG base station or the SCG base station (if it is reported to the SCG base station, the SCG base station may inform the MCG base station of the MCG radio connection failure of the terminal). In detail, since the UE detects an MCG radio connection failure, all SRBs or DRBs set in the set MCG are stopped transmitting to the MCG base station. Then, the MCG MAC layer device is initialized. However, bearers or layer devices set in the SCG are characterized in that they are not initialized and can be maintained and data transmission/reception can continue. Then, if the T304 timer (a timer that is activated in case of handover) is running, it stops (since a radio failure can be detected during handover). In addition, a split SRB connected to the SCG MAC layer device by indicating the type of MCG wireless connection failure (e.g., exceeding the maximum number of RLC retransmissions, or failing to verify integrity, or out of synchronization, or expiring a timer, etc.), and configuring an MCG radio failure message. For example, the MCG radio connection failure may be reported to the MCG base station or the SCG base station through the split SRB1) or the SRB connected to the SCG MAC layer device (for example, SRB3). In addition, the failure information may include measurement results for other frequencies so that the base station can use it to quickly set up a new cell (eg, Pcell) or a new cell group (eg, MCG). In addition, the reason for the failure may be indicated in the wireless connection failure information. Method 1 is a method in which the UE instructs MCG failure information so that the base station can recover or change the MCG in which the radio failure is indicated, and is a method for solving based on the MCG base station or the SCG base station. And you can start a second timer. (As described above, as a procedure for responding to the MCG radio connection failure report message, an RRC message instructing a handover instructing the base station to recover the radio connection, an RRC message instructing the RRC connection re-establishment, or the MCG disconnection When an RRC message such as an RRC message to be performed is received as a response, the second timer may be stopped or initialized.)

◆ Method 2: The UE stops transmission to the MCG base station for all SRBs or DRBs except for SRB0 because it has detected an MCG radio connection failure (SRB0 has to transmit an RRC re-establishment message. Can not be done). Then, the MCG MAC layer device is initialized. However, bearers or layer devices set in the SCG are characterized in that they are not initialized and can be maintained and data transmission/reception can continue. Then, if the T304 timer (a timer that is activated in case of handover) is running, it stops (since a radio failure can be detected during handover). The terminal may trigger an RRC connection reestablishment procedure for a suitable Scell selected through an MCG base station or a cell reselection procedure or for a cell supported by an SCG base station for which a valid connection has been established, and in the above procedure, the RRC When transmitting the connection re-establishment request message, it may be indicated that the MCG wireless connection failure has occurred. In addition, the reason for the failure may be indicated in the wireless connection failure information. Method 2 is a method in which the terminal checks the MCG failure information and allows the terminal to resolve itself.

◆ Method 3: Since the UE detects an MCG radio connection failure, it stops transmission to the MCG base station for all configured SRBs or DRBs. Then, the MCG MAC layer device is initialized. However, bearers or layer devices set in the SCG are characterized in that they are not initialized and can be maintained and data transmission/reception can continue. Then, if the T304 timer (a timer that is activated when handover) is running, it stops (because a radio failure can be detected during handover). The terminal may report the MCG radio connection failure to the MCG base station or the SCG base station (when reporting to the SCG base station, the SCG base station may inform the MCG base station of the MCG radio connection failure of the terminal). Specifically, the terminal may trigger an RRC connection reestablishment procedure for the MCG base station or the SCG base station. It can be indicated to the MCG base station or the SCG base station. In the above procedure, when transmitting the RRC connection re-establishment request message, it indicates that the MCG radio connection failure has occurred. Split SRB connected to the SCG MAC layer device (e.g., split SRB1) or SRB connected to the SCG MAC layer device (for example, SRB3 or SRB0) can be indicated. In addition, the reason for the failure may be indicated in the wireless connection failure information. Method 3 is a method in which the terminal instructs the MCG failure information to split SRB1 or SRB3 so that the base station can recover or change the MCG in which the radio failure is indicated. Or, it is a method that can be resolved based on the SCG base station. And you can start a second timer. (As described above, as a procedure for responding to the MCG radio connection failure report message, an RRC message instructing a handover instructing the base station to recover the radio connection, an RRC message instructing the RRC connection re-establishment, or the MCG disconnection When an RRC message such as an RRC message to be performed is received as a response, the second timer may be stopped or initialized.)

◆ Method 4: Since the UE detects the MCG radio connection failure, it stops the transmission to the MCG base station for all SRBs or DRBs except for the configured SRB0 (SRB0 has to transmit an RRC re-establishment message. Can not be done). Then, the MCG MAC layer device is initialized. However, bearers or layer devices set in the SCG are characterized in that they are not initialized and can be maintained and data transmission/reception can continue. Then, if the T304 timer (a timer that is activated in case of handover) is running, it stops (since a radio failure can be detected during handover). The terminal may report the MCG radio connection failure to the MCG base station or the SCG base station (when reporting to the SCG base station, the SCG base station may inform the MCG base station of the MCG radio connection failure of the terminal). Specifically, the terminal may trigger an RRC connection reestablishment procedure for the MCG base station or the SCG base station, that is, after camping on a cell having a good signal through a cell reselection procedure or an SCG with a valid connection It transmits an RRC connection re-establishment request message through SRB0 to a cell supported by the MCG radio connection failure in the above, it can be indicated to the MCG base station or the SCG base station using an indicator. In addition, the reason for the failure may be indicated in the wireless connection failure information. Method 4 is a method in which the UE instructs the MCG failure information to SRB0 so that the base station can recover or change the MCG in which the radio failure is indicated, so that the MCG base station or the SCG base station can resolve it.

■ If the dual access technology is not configured in the terminal, the SCG transmission is stopped, data transmission/reception is impossible, and the split SRB (for example, split SRB1) connected to the SCG base station or the SRB is not configured in the terminal, or first The timer of or the second timer has expired, or otherwise

◆ The UE stops transmission to the MCG base station for all SRBs or DRBs except for the configured SRB0 because the MCG radio connection failure is detected (SRB0 must not stop the transmission because it must transmit an RRC re-establishment message). Then, the MCG MAC layer device is initialized. In addition, it is characterized in that all bearers (SRB or DRB) set in the SCG are stopped and the SCG MAC layer device is also initialized, and the SCG bearers and SCG configuration information are released. Then, if the T304 timer (a timer that is activated in case of handover) is running, it stops (since a radio failure can be detected during handover). The terminal may report the MCG radio connection failure to the MCG base station or the SCG base station (when reporting to the SCG base station, the SCG base station may inform the MCG base station of the MCG radio connection failure of the terminal). Specifically, the terminal may trigger an RRC connection reestablishment procedure for the MCG base station or the SCG base station, that is, the terminal has a valid connection or for a suitable Scell selected through the MCG base station or cell reselection procedure. After camping on the cell supported by the configured SCG base station, the RRC connection re-establishment request message is transmitted through SRB0, and the MCG base station or the SCG base station can be indicated that the MCG radio connection failure has occurred using an indicator. have. In addition, the reason for the failure may be indicated in the wireless connection failure information.

As suggested above, in the terminal in which the carrier aggregation technology is configured, the Scell maintains connection with the base station (or cell), but if a wireless connection failure occurs with the base station (or cell) in the Pcell, the terminal continuously transmits and receives data from the Scells. And, the base station restores the Pcell, releases the Pcell in which the radio failure has occurred, and adds a new cell to be used as a Pcell, or the Scell that satisfies the plurality of conditions among the Scells for which the current wireless connection is maintained acts as a Pcell. In order to be able to change and use, continuous data transmission may be possible by allowing the terminal to report the wireless connection failure of the Pcell to the MCG base station through the Scell that satisfies the plurality of conditions.

In the above, when the MCG base station receives a report of the wireless connection failure of the Pcell, it recovers the Pcell of the terminal, releases the Pcell in which the wireless failure has occurred, and adds a new cell to be used as a Pcell, or among Scells for which the current wireless connection is maintained. Configuration information may be transmitted to the base station as an RRC message through the Scell satisfying the plurality of conditions so that the Scell satisfying the plurality of conditions can be used by changing its role to the Pcell. Specifically, it may be instructed to release the existing Pcell configuration information, or transmit new cell configuration information, inform random access information to be used in the random access procedure, establish a connection to a new cell, and instruct to use it as a Pcell, or The random access information to be used in the random access procedure may be informed to try to connect to the Pcell again. As another method, the base station configures the RRC message with information instructing the terminal to consider the Scell configuration information previously set to the terminal as a Pcell, and configures the Scell that satisfies a plurality of conditions connected to the MCG MAC layer device of the terminal. It can be transmitted through. Therefore, a cell that used to be an Scell can be regarded as a Pcell (for example, it can be set to be regarded as a Pcell by setting the cell identifier of the previously set Scell to 0). When the role of the existing Scell is changed to the Pcell, the base station may configure the carrier aggregation technology again by setting another cell to be added as the SCell.

In the above, when the MCG base station receives a report of the wireless connection failure of the Pcell, it recovers the MCG of the terminal, releases the MCG in which the wireless failure has occurred, and adds a new cell to be used as an MCG, or uses the SCG for which the current wireless connection is maintained. The configuration information can be transmitted to the base station in an RRC message through the SCG so that the role can be changed and used. Specifically, it can be instructed to release the existing MCG setting information, or it can transmit new cell setting information, inform random access information to be used in the random access procedure, establish a connection to a new cell, and instruct to use it as an MCG, or The random access information to be used in the random access procedure may be notified so that the MCG tries to connect again. As another method, the base station can configure information in the RRC message to instruct the terminal to consider the SCG configuration information previously set to the terminal as MCG, and transmit it through the SRB connected to the terminal's MCG or SCG MAC layer device. have. Therefore, a cell that used to be an SCG can be regarded as an MCG (for example, a cell group identifier of the previously set SCG can be set to be set to 0 to be regarded as an MCG), and the role of the existing SCG is changed to MCG. If so, the base station can configure the dual access technology again by setting another cell to be added to the SCG.

Alternatively, the SCG base station may send an RRC connection re-establishment message to the terminal to instruct the terminal to restore the radio connection in the SCG. Therefore, the terminal triggers the RRC re-establishment procedure to send an RRC re-establishment request message to the base station, receives the RRC re-establishment message from the base station, and sends an RRC re-establishment completion message to the base station again to restore the radio connection, not the base station (e.g. For example, if the SCG) checks the MCG radio connection failure, the base station (e.g., SCG) triggers an RRC re-establishment procedure to send an RRC re-establishment message to the terminal, and the terminal confirms this and sends an RRC re-establishment completion message to the base station. To restore the wireless connection. And the base station (e.g., SCG) indicates that the terminal has re-established the connection to itself (e.g., SCG) to the base station (e.g., MCG) from which the terminal has failed wireless connection, so that the context of the terminal is set to the base station (e.g. For example, MCG) can release it.

In addition, in the MCG radio failure reporting method of the present invention, if the terminal performs the MCG radio failure report with the split SRB1 set in the MCG MAC layer device and the SCG MAC layer device, the first RLC when the packet redundancy function is not configured. Change the configuration of the primary RLC entity to a secondary RLC entity and configure the secondary RLC entity to the primary RLC entity. By changing, the MCG radio failure report message transmitted by the terminal can be transmitted, and the PDCP control data (PDCP control PDU) generated or triggered by the PDCP layer device is transmitted through the split SRB1 connected to the SCG MAC layer device. As a result, the receiving base station can successfully receive the MCG radio failure report message or PDCP control data. If the above-described configuration change is required, if packet duplication is set in the split SRB1, the terminal can transmit data to the second RLC layer device, but if the packet duplication function is not set, the data is sent to the second RLC layer device. This is because (MCG wireless connection failure report or PDCP control data) cannot be transmitted. Alternatively, it may be allowed to transmit the MCG radio connection failure report or PDCP control data to the second RLC layer device only when the MCG radio connection failure report procedure is triggered. In the above, if the setting of the first RLC layer device to the second RLC layer device for the split SRB1 is changed, when a response to recovery of the MCG failure report is received, it may be returned to the original configuration, or It may be kept until an RRC message to change the settings is received.

The above embodiments can be extended and applied even when both the frequency aggregation technology and the dual access technology are configured in the terminal.

The split SRB (e.g., split SRB1) described in the present invention has one PDCP layer device for MCG in the UE implementation, and one RLC layer device for MCG and one for SCG in the one PDCP layer device. It has a structure in which RLC layer devices are connected, and one RLC layer device for the MCG is connected to a MAC layer device for MCG and a PHY layer device, and one RLC layer device for the SCG is a MAC layer device for SCG. It may be characterized by having a structure that is connected to the PHY layer device. And from the standpoint of the base station, the MCG base station has one PDCP layer device, and the one PDCP layer device has one RLC layer device for MCG and an X interface (for example, X2, Xn, etc.) or an S interface (for example, S1, Sn, etc.) has a structure in which one RLC layer device for SCG is connected in the SCG base station connected through, and one RLC layer device for the MCG is connected to the MAC layer device and the PHY layer device of the MCG base station, One RLC layer device for the SCG may be characterized in that it has a structure that is connected to the MAC layer device and the PHY layer device of the SCG base station.

In addition, the SRB3 described in the present invention has one PDCP layer device for SCG in the terminal implementation, has a structure in which one RLC layer device for SCG is connected to the one PDCP layer device, and one for the SCG The RLC layer device may be characterized in that it has a structure that is connected to the MAC layer device and the PHY layer device for SCG. And from the standpoint of the base station, the SCG base station has one PDCP layer device, and one RLC layer device for SCG is connected to the one PDCP layer device, and one RLC layer device for the MCG is the MCG base station. It is connected to the MAC layer device and the PHY layer device, and one RLC layer device for the SCG may be characterized in that it has a structure that is connected to the MAC layer device and the PHY layer device of the SCG base station.

In the second or fourth embodiment of the present invention, after performing the procedure for reporting the failure of the MCG wireless connection to the base station through the SCell or SCG, if the first timer or the second timer If a wireless connection failure occurs in the SCell or SCG that performed the MCG wireless connection failure report before expiration or before receiving a response to the MCG wireless connection failure report, the terminal determines that all wireless connections have failed and re-establishes the RRC connection. (RRC Connection Reestablishment) procedure can be triggered.

In the second embodiment of the present invention, when the MCG radio connection failure is confirmed, the UE stops bearers for all bearers except SRB0 for bearers configured for MCG (e.g., data transmission/reception stop or SDAP of each bearer). Alternatively, data processing may be stopped in a PDCP or RLC or MAC layer device). In addition, since the connection with the MCG may be established again, the MAC initialization may not be performed. However, data transmission/reception and data processing may be continuously performed on bearers set for the SCG.

In the second or fourth embodiment of the present invention, when the MCG radio connection failure is confirmed, the terminal may perform the MCG radio connection failure reporting procedure to the SCell of the MCG that satisfies a predetermined condition. Specifically, the UE stops bearers for all bearers except SRB0 or SRB1 for bearers configured for MCG (e.g., stops data transmission/reception or stops data processing in SDAP or PDCP or RLC or MAC layer devices of each bearer. ) Can be performed. In addition, since the connection with the MCG may be established again, the MAC initialization may not be performed. However, when the dual access technology is configured, data transmission/reception and data processing may be continuously performed on bearers configured for the SCG. In the above, the MAC layer device may not be initialized, but a partial MAC reset procedure may be performed. That is, in the fourth embodiment, if a frequency aggregation technology is set in the UE and a SCell that satisfies a predetermined condition is set, the RRC layer device of the UE when an MCG radio connection failure is detected is the UE in the MCG MAC layer device. A partial MAC reset procedure may be instructed to transmit an MCG radio connection failure report message to the SCell. The partial MAC initialization procedure is a preparatory operation of the MAC layer device for initializing processing information of data that has been transmitted/received while maintaining the settings of the existing MAC layer device, and reporting a new transmission or MAC wireless connection failure. In addition, even if an MCG wireless connection failure is detected, the MCG wireless connection failure report message can be reported to the MCG MAC layer device.

In the above, the partial MAC initialization procedure may include one or more of the following procedures.

-If a higher layer device (eg, an RRC layer device) instructs partial initialization of the MAC layer device, the MAC layer device may perform one or more of the following procedures. As another method, the MAC layer device may perform one or more of the following procedures for the SCell that satisfies the predetermined condition.

■ In order to initialize information on previously transmitted/received data, NDI values for all uplink transmission HARQ processes are set to 0.

■ Initialize information on previously transmitted/received data All uplink transmission HARQ buffers are emptied.

■ Stop the DRX uplink retransmission timer during all driving.

■ Stop all running uplink HARQ RTT timers.

■ If there is a random access procedure in progress, stop it.

■ If there is specific information related to the random access preamble or random access transmission resource information, it is discarded.

■ Initialize the message 3 buffer.

■ If there is a temporary C-RNTI set temporarily, cancel it.

In the fourth embodiment of the present invention, if the terminal detects MCG wireless connection failure and satisfies a predetermined condition, the SCell is configured, the dual access technology is set, and the wireless connection with the SCG is valid, and the terminal is split If SRB (for example, split SBR1) is configured, the UE can report MCG radio connection failure through the split SRB. Specifically, the terminal configures the MCG radio connection failure report message, performs data processing in the PDCP layer device of the MCG for the split SRB1, and the MCG MAC layer device through the RLC layer device connected to the MCG MAC layer device. The MCG radio connection failure report message may be transmitted to a SCell that satisfies a predetermined condition. In addition, the terminal configures the MCG radio connection failure report message, performs data processing in the PDCP layer device of the MCG for the split SRB1, and PSCell in the SCG MAC layer device through the RLC layer device connected to the SCG MAC layer device. Alternatively, the MCG radio connection failure report message may be transmitted to the SCell. As another method, the terminal configures the MCG radio connection failure report message, performs data processing in the PDCP layer device of the MCG for the split SRB1, and duplicates the MCG radio connection failure report message by processing the data redundantly. The MCG radio connection failure report message is transmitted from the MCG MAC layer device to the SCell that satisfies the predetermined condition through the RLC layer device connected to the MAC layer device, and also through the RLC layer device connected to the SCG MAC layer device. The MCG radio connection failure report message may be transmitted from the SCG MAC layer device to the PSCell or SCell. That is, if a direct frequency technology is set for the terminal, a SCell that satisfies a predetermined condition is set, a dual access technology is set for the terminal, and the wireless connection with the SCG PSCell or SCG Scell is greater than a certain signal strength, When the UE detects the MCG radio failure, the MCG radio failure report message is constructed and generated, and packet redundancy is applied to the MCG PDCP layer device. The MCG radio failure report message is packet redundantly processed in the MCG PDCP layer device, and the MCG RLC using split SRB1. Through the layer device, the MCG MAC layer device transmits redundantly from the MCG MAC layer device to the Scell, and the SCG MAC layer device transmits the MCG failure report message with low transmission delay and high reliability by repeatedly transmitting through the PScell or Scell through the SCG RLC layer device. can do.

1H shows that if a wireless connection failure (MCG wireless connection failure) with a base station (or cell) occurs in a Pcell in a terminal configured with a carrier aggregation technology or dual access technology in embodiments of the present invention, the terminal continues data transmission in the Scell or SCG. A specific Scell or SCG to transmit and receive, recover a Pcell or MCG, change to another Pcell or MCG, release a Pcell or MCG in which the radio failure has occurred, or convert a Scell or SCG with a current connection to a Pcell or MCG. It shows the specific terminal operation that reports the PCell's wireless connection failure (MCG wireless connection failure).

In the terminal, a wireless connection failure (MCG wireless connection failure) with a base station (or cell) in the Pcell may be generated or detected (1h-05).

In this case, if a carrier aggregation technology is set in the terminal, the first condition, the second condition, the third condition, the fourth condition, the fifth condition, or the sixth condition is satisfied among the set Scells. If the Scell is configured (1h-10), the UE may report a wireless connection failure of the Pcell through the Scell. Specifically, the UE configures an RRC message for Pcell radio connection failure information, configures the information as data in the MCG MAC layer device through the SRB1 or SRB2 bearer, that is, the logical channel identifier corresponding to SRB1 or SRB2, and configures the plurality of conditions. The information about the wireless connection failure of the Pcell can be transmitted to the base station with a satisfactory Scell (1h-15).

If the terminal does not have a carrier aggregation technology, or among the configured Scells, Scells that satisfy the first condition, the second condition, the third condition, the fourth condition, the fifth condition, or the sixth condition If this is not set, and if the terminal is configured with dual access technology, the SCG is not stopped and data transmission and reception is possible, and the MCG MAC layer device of the terminal is connected to the MCG base station (with a PDCP layer device in the MCG) And a split SRB connected to the SCG MAC layer device (eg, split SRB1) or an SRB connected to the SCG MAC layer device (eg, SRB3) connected to the SCG base station (with a PDCP layer device in the SCG) (1h-20) The terminal may report the MCG radio connection failure to the MCG base station or the SCG base station (when reporting to the SCG base station, the SCG base station may inform the MCG base station of the MCG radio connection failure of the terminal) ( 1h-25).

If the dual access technology is not configured in the terminal, the SCG transmission is stopped, data transmission/reception is impossible, and the split SRB (e.g., split SRB1) connected to the SCG base station or the SRB is not configured in the terminal, or otherwise Ramen (1h-30) The UE stops transmission to the MCG base station for all SRBs or DRBs except for the configured SRB0 because it has detected an MCG radio connection failure (SRB0 must transmit an RRC re-establishment message. Do not stop). Then, the MCG MAC layer device is initialized. In addition, it is characterized in that all bearers (SRB or DRB) set in the SCG are stopped and the SCG MAC layer device is also initialized, and the SCG bearers and SCG configuration information are released. Then, if the T304 timer (a timer that is activated in case of handover) is running, it stops (since a radio failure can be detected during handover). The terminal may report the MCG radio connection failure to the MCG base station or the SCG base station (when reporting to the SCG base station, the SCG base station may inform the MCG base station of the MCG radio connection failure of the terminal). Specifically, the terminal can trigger an RRC connection reestablishment procedure for an MCG base station or an SCG base station, that is, after camping on a cell having a good signal through a cell reselection procedure, an RRC connection through SRB0 The re-establishment request message is transmitted, and the MCG base station or the SCG base station may be indicated that the MCG radio connection failure has occurred using an indicator. In addition, the reason for the failure may be indicated in the wireless connection failure information.

The embodiments of the present invention may be extended to a procedure for reporting the failure of the PSCell to the SCG base station using the SCG of the SCG when a connection failure occurs in the PSCell of the SCG in a terminal configured with dual access technology and carrier aggregation technology. That is, in the above-proposed embodiments, the PScell connection failure of the SCG is considered instead of the PCell connection failure of the MCG, and the connection failure of the PSCell of the SCG is reported to the SCG of the SCG instead of reporting the PCell connection failure of the MCG to the SCell of the MCG. The embodiments can be expanded.

In the above embodiments of the present invention, when an MCG radio connection failure is detected, methods of reporting this to the base station have been proposed. If the base station receives the MCG radio connection failure report message, it may instruct the terminal to recover the MCG radio connection failure by one of the following methods.

-Method 1: If the Scell is connected to the base station (or cell) in the terminal for which the frequency aggregation technology is configured, but a wireless connection failure occurs with the base station (or cell) in the Pcell, the terminal continues to transmit and receive data from the Scells. And, the base station restores the Pcell, releases the Pcell in which the radio failure has occurred, and adds a new cell to be used as a Pcell, or the Scell that satisfies the plurality of conditions among the Scells for which the current wireless connection is maintained acts as a Pcell. The RRC message can be set to the terminal so that it can be changed and used. That is, when the MCG base station receives a report of the radio connection failure of the MCG (or Pcell), it recovers the Pcell of the terminal, releases the Pcell in which the radio failure has occurred, and adds a new cell to be used as a Pcell, or the current radio connection is maintained. Among the Scells, configuration information may be transmitted to the base station in an RRC message through an Scell satisfying the plurality of conditions so that the Scell satisfying the plurality of conditions can be used by changing its role to a Pcell. Specifically, it may be instructed to release the existing Pcell configuration information, or transmit new cell configuration information, inform random access information to be used in the random access procedure, establish a connection to a new cell, and instruct to use it as a Pcell, or The random access information to be used in the random access procedure may be informed to try to connect to the Pcell again. As another method, the base station configures the RRC message with information instructing the terminal to consider the Scell configuration information previously set to the terminal as a Pcell, and configures the Scell that satisfies a plurality of conditions connected to the MCG MAC layer device of the terminal. It can be transmitted through. Therefore, a cell that used to be an Scell can be regarded as a Pcell (for example, it can be set to be regarded as a Pcell by setting the cell identifier of the previously set Scell to 0). When the role of the existing Scell is changed to the Pcell, the base station may configure the carrier aggregation technology again by setting another cell to be added as the SCell.

-Method 2: In the above, when the MCG base station receives a report of the wireless connection failure of the MCG (or Pcell), it recovers the MCG of the terminal, releases the MCG in which the wireless failure has occurred, and adds a new cell to be used as an MCG, or The configuration information may be transmitted to the base station as an RRC message through the SCG so that the SCG in which the connection is maintained can be used by changing the role to the MCG. Specifically, it can be instructed to release the existing MCG setting information, or it can transmit new cell setting information, inform random access information to be used in the random access procedure, establish a connection to a new cell, and instruct to use it as an MCG, or The random access information to be used in the random access procedure may be notified so that the MCG tries to connect again. As another method, the base station can configure information in the RRC message to instruct the terminal to consider the SCG configuration information previously set to the terminal as MCG, and transmit it through the SRB connected to the terminal's MCG or SCG MAC layer device. have. Therefore, a cell that used to be an SCG can be regarded as an MCG (for example, a cell group identifier of the previously set SCG can be set to be set to 0 to be regarded as an MCG), and the role of the existing SCG is changed to MCG. If so, the base station can configure the dual access technology again by setting another cell to be added to the SCG.

-Method 3: As another method, the SCG base station may send an RRC connection re-establishment message to the terminal to instruct the terminal to restore the radio connection in the SCG. Therefore, the terminal triggers the RRC re-establishment procedure to send an RRC re-establishment request message to the base station, receives the RRC re-establishment message from the base station, and sends an RRC re-establishment completion message to the base station again to restore the radio connection, not the base station (e.g. For example, if the SCG) checks the MCG radio connection failure, the base station (e.g., SCG) triggers an RRC re-establishment procedure to send an RRC re-establishment message to the terminal, and the terminal confirms this and sends an RRC re-establishment completion message to the base station. To restore the wireless connection. And the base station (e.g., SCG) indicates that the terminal has re-established the connection to itself (e.g., SCG) to the base station (e.g., MCG) from which the terminal has failed wireless connection, so that the context of the terminal is set to the base station (e.g. For example, MCG) can release it.

When applying the above-proposed methods, the terminal initializes the configuration information for the SCG base station, receives the new configuration from the base station, and may receive dual access technology. When applying the proposed methods as another method, the terminal Although the configuration information for the SCG base station is maintained, the MAC layer device may be initialized, and the RLC layer device and the PDCP layer device may be re-established. As another method, the UE applies the methods proposed above and can continue to transmit and receive data with the SCG base station.

In the following of the present invention, in order to prevent interruption of data transmission/reception when applying Method 1, Method 2, or Method 3 proposed above, when the terminal continues to transmit and receive data with the SCG base station, or when the terminal receives a handover instruction from the base station. And, when the dual access technology is configured for the terminal, a problem that may occur when the terminal performs handover to the MCG base station while maintaining data transmission and reception with the SCG base station is presented, and a solution method thereof is proposed.

First, when the base station instructs the terminal to handover to a new cell or base station as a method for recovering the MCG radio failure, or when the terminal in which the dual access technology is configured continues data transmission and reception with the SCG and instructs the handover of the MCG, The terminal receives a new security key for the MCG base station, and must perform encryption and decryption or integrity protection and integrity verification procedures in the PDCP layer device by inducing and applying a new security key value. In addition, when the security key value of the MCG base station is changed, the security key value for the corresponding SCG base station must be newly derived and updated. Therefore, if the MCG security key value is changed due to handover or recovery of the MCG while maintaining data transmission/reception with the SCG, the security key value is changed during data transmission/reception between the SCG and the terminal. Therefore, the terminal and the base station cannot distinguish which data has been encrypted and integrity protected with an old security key or whether encryption and integrity protection has been applied with a new security key.

Accordingly, the present invention proposes methods by which the UE and the base station can distinguish whether an old security key or a new security key is applied for each data in the PDCP layer device as described above.

-Method 1: When the security key value is changed while data transmission/reception is in progress as described above, the base station initializes the MAC layer device, re-establishes the RLC layer device, or reestablishes the PDCP layer device. By instructing, the PDCP layer device can distinguish between data to which the old security key is applied (for example, PDCP PDU or PDCP SDU) and data to which the new security key is applied.

-Method 2: When the security key value is changed while data transmission/reception is in progress as described above, a new PDCP control PDU can be defined and used to indicate this. The new PDCP control PDCU can be used as an end marker, and a security key value that is old to some data (for example, PDCP PDU or PDCP SDU) including the last PDCP serial number or COUNT value to which the old security key value is applied. Is applied, and from which data the new security key value is applied can be indicated. As another method, the new PDCP control PDCU can be used as a first marker, and some data (e.g. PDCP PDU or PDCP SDU) including the first PDCP serial number or COUNT value to which the new security key value is applied. From, you can indicate to which data the new security key value was applied, and to what data the old security key value was applied. The PDCP control PDU proposed above can be transmitted for each bearer when the security key value is changed.

-Method 3: When the security key value is changed while data transmission/reception is in progress as described above, a 1-bit indicator is defined in the PDCP header of the PDCP layer device to indicate this, and corresponding to the PDCP header using the indicator Data can indicate whether an old security key value has been applied or a new security key value has been applied. When the PDCP control PDU proposed in Method 2 is transmitted for each bearer because the security key value is changed, it may not be lost in the RLC AM mode, but may be lost in the RLC UM mode. In addition, since the NR RLC layer device transmits data to the PDCP layer device in an out of order delivery method, when the PDCP control PDU arrives late, a decoding failure may occur in the receiving PDCP layer device. On the other hand, since the 1-bit indicator of the PDCP header proposed in Method 3 can indicate whether an old security key value or a new security key value is applied for each data, even if the NR RLC layer device performs out of order transmission, and Even if data is lost, the receiving PDCP layer device can process the non-lost data more efficiently. In the above, the 1-bit indicator of the PDCP header is a 1-bit indicator of the PDCP header and confirms successful delivery of the first data indicated that a new security key has been set or the last data to which the old security key has been applied (RLC ACK) or When it is confirmed from the received PDCP status report, the 1-bit indicator may not be set any more. As another method, the 1-bit indicator may not be set after the MCG handover is completed. Alternatively, the 1-bit indicator may be set or canceled according to an instruction of an RRC message or a handover command message. As another method, the 1-bit indicator may be used by applying a toggle method. That is, whenever the security key value is changed, the 1-bit indicator of the PDCP header may be toggled from 0 to 1 or may be toggled from 1 to 0 to indicate. As another method, the receiving PDCP layer device (base station or terminal) checks the 1-bit indicator of the PDCP header and transmits feedback to the transmitting PDCP layer device (terminal or base station) that it can normally distinguish between a new security key and an old security key. Until then, the 1-bit indicator may be used, and the feedback may be used by defining a new PDCP control PDU.

In the present invention, when a carrier aggregation technology is set when an MCG (or PCell) radio failure is detected, a method of reporting an MCG (or PCell) radio connection failure through the SCell of the MCG or a dual access technology is set, through the SCG. (For example, SRB3 or split SRB1) A method of reporting an MCG (or PCell) radio connection failure is proposed.

In the following of the present invention, conditions for performing each proposed method according to different conditions of the methods proposed in the present invention are proposed, and a specific fifth embodiment will be described as follows.

A 5-1 embodiment in which the first embodiment, the second embodiment, the third embodiment, or the fourth embodiment proposed in the present invention is performed according to different conditions is as follows. In the 5-1 embodiment, when an MCG (or PCell) radio failure is detected, if both the dual access technology and the carrier aggregation technology are configured to the terminal, first reporting the MCG (or PCell) radio failure using the dual access technology. In the dual access technology, if both SRB3 and split SRB1 are configured, an MCG (or PCell) radio failure may be reported through SRB3. This is because if the connection to the SCG base station operates normally, the connection to the SCG can be determined to be more reliable than the SCell of the MCG, and it can be determined that the SRB3 connected to the SCG is more reliable than the split SRB1. If SRB3 is not set in the above, it is reported as split SRB1, and if there is an MCG SCell that satisfies a predetermined condition and split SRB1 or SRB3 is not set, a radio connection failure can be reported to the SCell. If the MCG radio connection failure cannot be reported as described above, the terminal may trigger an RRC connection re-establishment procedure to reset the connection.

-If the dual access technology is configured for the terminal when MCG (or PCell) radio failure is detected (or carrier aggregation technology is configured)

■ If the UE is configured with SRB3 connected to the SCG base station (or split SRB1 is configured)

◆ The terminal reports the radio failure of the MCG (or PCell) to the base station through SRB3. Reporting can be performed like the method proposed in the present invention (for example, in the second embodiment).

■ If not (else if) (or if SRB3 connected to the SCG base station to the UE is not configured or split SRB1 is configured)

◆ The terminal reports the MCG (or PCell) radio failure to the base station through split SRB1. Reporting can be performed like the method proposed in the present invention (for example, in the second embodiment). Alternatively, if the carrier aggregation technology is configured in the terminal and the SCell that satisfies a predetermined condition is configured, the MCG (or PCell) radio failure message is duplicated with the SCell of the MCG and the SCG through split SRB1 by applying the packet redundancy technology. It may be transmitted to report an MCG (or PCell) radio failure.

■ If not (else if) (or if an MCG (or PCell) radio failure is detected, SRB3 is not configured in the terminal, or split SRB1 is not configured, or a carrier aggregation technology is configured and a SCell that satisfies a predetermined condition If is set (for example, as in the fourth embodiment)

◆ The terminal reports an MCG (or PCell) radio failure to the base station through a SCell that satisfies a predetermined condition. Reports can be performed like the method proposed in the present invention (for example, in the fourth embodiment).

■ If not (else)

◆ The terminal triggers the RRC connection re-establishment procedure and resets the connection.

A 5-2 embodiment in which the first embodiment, the second embodiment, the third embodiment, or the fourth embodiment proposed in the present invention is performed according to different conditions is as follows. In the 5-2 embodiment, when an MCG (or PCell) radio failure is detected, if both the dual access technology and the carrier aggregation technology are set to the terminal, first reporting the MCG (or PCell) radio failure using the dual access technology. In the dual access technology, if both SRB3 and split SRB1 are configured, MCG (or PCell) radio failure may be reported through split SRB1. This is because if the connection to the SCG base station operates normally, it can be determined that the connection to the SCG is more reliable than the SCell of the MCG, and it can be determined that the split SRB1 directly connected to the MCG has a lower transmission delay than the SRB3 connected to the SCG. Because there is. If split SRB1 is not configured above, it is reported as SRB3, and if split SRB1 or SRB3 is not configured, and there is an MCG SCell that satisfies a predetermined condition, a radio connection failure may be reported to the SCell. If the MCG radio connection failure cannot be reported as described above, the terminal may trigger an RRC connection re-establishment procedure to reset the connection.

-If the dual access technology is configured for the terminal when MCG (or PCell) radio failure is detected (or carrier aggregation technology is configured)

■ If the terminal is configured with split SRB1 connected to the SCG base station (or SRB3 is configured)

◆ The terminal reports the MCG (or PCell) radio failure to the base station through split SRB1. Reporting can be performed like the method proposed in the present invention (for example, in the second embodiment). Alternatively, if the carrier aggregation technology is configured in the terminal and the SCell that satisfies a predetermined condition is configured, the MCG (or PCell) radio failure message is duplicated with the SCell of the MCG and the SCG through split SRB1 by applying the packet redundancy technology. It may be transmitted to report an MCG (or PCell) radio failure.

■ If not (else if) (or if the split SRB1 connected to the SCG base station to the UE is not configured or SRB3 is configured)

◆ The terminal reports the radio failure of the MCG (or PCell) to the base station through SRB3. Reporting can be performed like the method proposed in the present invention (for example, in the second embodiment).

■ If not (else if) (or if an MCG (or PCell) radio failure is detected, SRB3 is not configured in the terminal, or split SRB1 is not configured, or a carrier aggregation technology is configured and a SCell that satisfies a predetermined condition If is set (for example, as in the fourth embodiment)

◆ The terminal reports an MCG (or PCell) radio failure to the base station through a SCell that satisfies a predetermined condition. Reports can be performed like the method proposed in the present invention (for example, in the fourth embodiment).

■ If not (else)

◆ The terminal triggers the RRC connection re-establishment procedure and resets the connection.

Examples 5-3 in which the first embodiment, the second embodiment, the third embodiment, or the fourth embodiment proposed in the present invention are performed according to different conditions are as follows. In the 5th-3 embodiment, when an MCG (or PCell) radio failure is detected, if both the dual access technology and the carrier aggregation technology are set to the terminal, first reporting the MCG (or PCell) radio failure using the carrier aggregation technology. If there is no MCG SCell that satisfies the predetermined condition in the above, and both SRB3 and split SRB1 are configured in the dual access technology, MCG (or PCell) radio failure may be reported through split SRB1. . This is because if the connection to the MCG base station operates normally, it can be determined that the SCell of the MCG has a lower transmission delay, and it can be determined that the split SRB1 directly connected to the MCG has a lower transmission delay than the SRB3 connected to the SCG. Because there is. If split SRB1 is not configured above, it is reported as SRB3, and if the MCG radio connection failure cannot be reported as above because split SRB1 or SRB3 is not configured, the terminal may trigger an RRC connection re-establishment procedure to reset the connection. .

-If the carrier aggregation technology is configured in the terminal when the MCG (or PCell) radio failure is detected (or the dual access technology is configured)

■ If a SCell that satisfies a predetermined condition is configured when an MCG (or PCell) radio failure is detected (for example, as in the fourth embodiment)

◆ The terminal reports an MCG (or PCell) radio failure to the base station through a SCell that satisfies a predetermined condition. Reports can be performed like the method proposed in the present invention (for example, in the fourth embodiment). As another method, if the dual access technology is configured for the terminal and split SRB1 is configured, a packet redundancy technology is applied and the MCG (or PCell) radio failure message is duplicated and transmitted to the SCell and SCG of the MCG through the split SRB1. PCell) may report a radio failure.

■ If not (else if) (if the UE does not have an MCG SCell that satisfies a predetermined condition, or if a split SRB1 connected to the SCG base station is configured (or if SRB3 is configured)

◆ The terminal reports the MCG (or PCell) radio failure to the base station through split SRB1. Reporting can be performed like the method proposed in the present invention (for example, in the second embodiment).

■ If not (else if) (or if the UE does not have an MCG SCell that satisfies a predetermined condition, or if the split SRB1 connected to the SCG base station is not configured or SRB3 is configured)

◆ The terminal reports the radio failure of the MCG (or PCell) to the base station through SRB3. Reporting can be performed like the method proposed in the present invention (for example, in the second embodiment).

■ If not (else)

◆ The terminal triggers the RRC connection re-establishment procedure and resets the connection.

Embodiments 5-4 in which the first embodiment, the second embodiment, the third embodiment, or the fourth embodiment proposed in the present invention are performed according to different conditions are as follows. In the fifth embodiment, when the MCG (or PCell) radio failure is detected, if both the dual access technology and the carrier aggregation technology are set to the terminal, the MCG (or PCell) radio failure is first reported to the SCell using the carrier aggregation technology. If there is no MCG SCell that satisfies the predetermined condition above, and both SRB3 and split SRB1 are configured in the dual access technology, the MCG (or PCell) radio failure may be reported through SRB3. . This is because if the connection to the MCG base station operates normally, the MCG SCell can be determined to have a lower transmission delay, and it can be determined that the SRB3 connected to the SCG has a higher transmission reliability than the split SRB1 directly connected to the MCG. Because. If SRB3 is not configured above, it is reported as split SRB1, and if the MCG radio connection failure cannot be reported as above because split SRB1 or SRB3 is not configured, the terminal may trigger an RRC connection re-establishment procedure to reset the connection. .

-If the carrier aggregation technology is configured in the terminal when the MCG (or PCell) radio failure is detected (or the dual access technology is configured)

■ If a SCell that satisfies a predetermined condition is configured when an MCG (or PCell) radio failure is detected (for example, as in the fourth embodiment)

◆ The terminal reports an MCG (or PCell) radio failure to the base station through a SCell that satisfies a predetermined condition. Reports can be performed like the method proposed in the present invention (for example, in the fourth embodiment). As another method, if the dual access technology is configured for the terminal and split SRB1 is configured, a packet redundancy technology is applied and the MCG (or PCell) radio failure message is duplicated and transmitted to the SCell and SCG of the MCG through the split SRB1. PCell) may report a radio failure.

■ If not (else if) (if the UE does not have an MCG SCell that satisfies a predetermined condition or if SRB3 connected to the SCG base station is configured (or if split SRB1 is configured)

◆ The terminal reports the radio failure of the MCG (or PCell) to the base station through SRB3. Reporting can be performed like the method proposed in the present invention (for example, in the second embodiment).

■ If not (else if) (or if the terminal does not have an MCG SCell that satisfies a predetermined condition, or if SRB3 connected to the SCG base station is not configured or split SRB1 is configured)

◆ The terminal reports the MCG (or PCell) radio failure to the base station through split SRB1. Reporting can be performed like the method proposed in the present invention (for example, in the second embodiment).

■ If not (else)

◆ The terminal triggers the RRC connection re-establishment procedure and resets the connection.

In the above, SRB3 refers to a bearer that is set in the SCG of the terminal as an encrypted SRB so that the terminal can directly transmit an RRC message to the SCG base station through the SCG MAC layer device, and the SCG base station MCG the RRC message received through the SRB3. You can also pass it to. In the Split SRB1, one PDCP layer device is connected to the MCG or SCG, two RLC layer devices are connected to the one PDCP layer device to transmit and receive data, and one RLC layer device is an MCG MAC layer device. And another RLC layer device refers to an SRB connected to an SCG MAC layer device, wherein the PDCP layer device may be configured for MCG. Therefore, when the UE transmits the RRC message through split SRB1 to the MCG RLC layer device, it is directly transmitted to the MCG base station through the MCG MAC layer device, and if transmitted to the SCG RLC layer device, it is transmitted to the MCG base station through the SCG base station. May be, and may be transmitted to the MCG RLC layer device or the SCG RLC layer device using packet redundancy.

Embodiments 5-5 in which the first embodiment, the second embodiment, the third embodiment, or the fourth embodiment proposed in the present invention are performed according to different conditions are as follows. In the fifth embodiment, when an MCG (or PCell) radio failure is detected, if both the dual access technology and the carrier aggregation technology are set to the terminal, first reporting the MCG (or PCell) radio failure using the dual access technology. In the dual access technique, if both SRB3 and split SRB1 are configured, an MCG (or PCell) radio failure may be reported through SRB3 or split SRB1. This is because, if the connection to the SCG base station operates normally, it can be determined that the connection to the SCG is more reliable than the SCell of the MCG. If SRB3 or split SRB1 is not configured above, and there is an MCG SCell that satisfies a predetermined condition, a radio connection failure may be reported to the SCell. If the MCG radio connection failure cannot be reported as described above, the terminal may trigger an RRC connection re-establishment procedure to reset the connection.

-If the dual access technology is configured for the terminal when MCG (or PCell) radio failure is detected (or carrier aggregation technology is configured)

■ If the UE is configured with SRB3 connected to the SCG base station (or split SRB1 is configured)

◆ The UE reports an MCG (or PCell) radio failure to the base station through SRB3 or split SRB1. Reporting can be performed like the method proposed in the present invention (for example, in the second embodiment). Alternatively, if the carrier aggregation technology is configured in the terminal and the SCell that satisfies a predetermined condition is configured, the MCG (or PCell) radio failure message is duplicated with the SCell of the MCG and the SCG through split SRB1 by applying the packet redundancy technology. It may be transmitted to report an MCG (or PCell) radio failure.

■ If not (else if) (or if an MCG (or PCell) radio failure is detected, SRB3 is not configured in the terminal, or split SRB1 is not configured, or a carrier aggregation technology is configured and a SCell that satisfies a predetermined condition If is set (for example, as in the fourth embodiment)

◆ The terminal reports an MCG (or PCell) radio failure to the base station through a SCell that satisfies a predetermined condition. Reports can be performed like the method proposed in the present invention (for example, in the fourth embodiment).

■ If not (else)

◆ The terminal triggers the RRC connection re-establishment procedure and resets the connection.

In the methods proposed in the present invention, if the terminal detects an MCG (or PCell) wireless connection failure and reports the wireless connection failure to SRB3 or split SRB1 using a dual access technology, or a predetermined condition using a carrier aggregation technology When a radio connection failure is reported to the SCell of the MCG that satisfies the above, but the proposed first timer or the second timer expires (for example, an RRC message corresponding to the MCG radio connection failure report until the timer expires) Is not received from the base station), the terminal may trigger an RRC connection re-establishment procedure and reset the connection.

Figure 1i shows the structure of a terminal to which an embodiment of the present invention can be applied.

Referring to the drawing, the terminal includes a radio frequency (RF) processing unit 1i-10, a baseband processing unit 1i-20, a storage unit 1i-30, and a control unit 1i-40. .

The RF processing unit 1i-10 performs functions for transmitting and receiving signals through a wireless channel, such as band conversion and amplification of signals. That is, the RF processing unit 1i-10 up-converts the baseband signal provided from the baseband processing unit 1i-20 to an RF band signal, and then transmits it through an antenna, and an RF band signal received through the antenna. Is down-converted to a baseband signal. For example, the RF processing unit 1i-10 may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a digital to analog convertor (DAC), an analog to digital convertor (ADC), and the like. I can. In the drawing, only one antenna is shown, but the terminal may include a plurality of antennas. In addition, the RF processing unit 1i-10 may include a plurality of RF chains. Furthermore, the RF processing unit 1i-10 may perform beamforming. For the beamforming, the RF processing unit 1i-10 may adjust a phase and a magnitude of each of signals transmitted/received through a plurality of antennas or antenna elements. In addition, the RF processing unit may perform MIMO, and may receive multiple layers when performing the MIMO operation. The RF processing unit 1i-10 may perform reception beam sweeping by appropriately setting a plurality of antennas or antenna elements under control of the controller, or adjust the direction and beam width of the reception beam so that the reception beam cooperates with the transmission beam. have.

The baseband processing unit 1i-20 performs a function of converting between a baseband signal and a bit stream according to the physical layer standard of the system. For example, when transmitting data, the baseband processing unit 1i-20 generates complex symbols by encoding and modulating a transmission bit stream. In addition, when receiving data, the baseband processing unit 1i-20 restores a received bit stream through demodulation and decoding of the baseband signal provided from the RF processing unit 1i-10. For example, in the case of the OFDM (orthogonal frequency division multiplexing) scheme, when transmitting data, the baseband processing unit 1i-20 generates complex symbols by encoding and modulating a transmission bit stream, and subcarriers of the complex symbols After mapping to, OFDM symbols are constructed through an inverse fast Fourier transform (IFFT) operation and a cyclic prefix (CP) insertion. In addition, when receiving data, the baseband processing unit 1i-20 divides the baseband signal provided from the RF processing unit 1i-10 in units of OFDM symbols, and applies a fast Fourier transform (FFT) operation to subcarriers. After reconstructing the mapped signals, the received bit stream is restored through demodulation and decoding.

The baseband processing unit 1i-20 and the RF processing unit 1i-10 transmit and receive signals as described above. Accordingly, the baseband processing unit 1i-20 and the RF processing unit 1i-10 may be referred to as a transmission unit, a reception unit, a transmission/reception unit, or a communication unit. Furthermore, at least one of the baseband processing unit 1i-20 and the RF processing unit 1i-10 may include a plurality of communication modules to support a plurality of different wireless access technologies. In addition, at least one of the baseband processing unit 1i-20 and the RF processing unit 1i-10 may include different communication modules to process signals of different frequency bands. For example, the different radio access technologies may include an LTE network, an NR network, and the like. In addition, the different frequency bands may include a super high frequency (SHF) (eg, 2.5GHz, 5Ghz) band, and a millimeter wave (eg, 60GHz) band.

The storage unit 1i-30 stores data such as a basic program, an application program, and setting information for the operation of the terminal. The storage unit 1i-30 provides stored data according to the request of the control unit 1i-40.

The control unit 1i-40 controls overall operations of the terminal. For example, the control unit 1i-40 transmits and receives signals through the baseband processing unit 1i-20 and the RF processing unit 1i-10. In addition, the control unit 1i-40 writes and reads data in the storage unit 1i-40. To this end, the control unit 1i-40 may include at least one processor. For example, the control unit 1i-40 may include a communication processor (CP) that controls communication and an application processor (AP) that controls an upper layer such as an application program.

1J is a block diagram of a TRP in a wireless communication system to which an embodiment of the present invention can be applied.

As shown in the figure, the base station includes an RF processing unit (1j-10), a baseband processing unit (1j-20), a backhaul communication unit (1j-30), a storage unit (1j-40), and a control unit (1j-50). Consists of including.

The RF processing unit 1j-10 performs a function of transmitting and receiving a signal through a wireless channel such as band conversion and amplification of a signal. That is, the RF processing unit 1j-10 up-converts the baseband signal provided from the baseband processing unit 1j-20 to an RF band signal and then transmits it through an antenna, and the RF band signal received through the antenna Downconverts to a baseband signal. For example, the RF processing unit 1j-10 may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, and the like. In the drawing, only one antenna is shown, but the first access node may include a plurality of antennas. In addition, the RF processing unit 1j-10 may include a plurality of RF chains. Furthermore, the RF processing unit 1j-10 may perform beamforming. For the beamforming, the RF processing unit 1j-10 may adjust a phase and a magnitude of each of signals transmitted and received through a plurality of antennas or antenna elements. The RF processor may perform a downlink MIMO operation by transmitting one or more layers.

The baseband processing unit 1j-20 performs a function of converting between a baseband signal and a bit stream according to the physical layer standard of the first wireless access technology. For example, when transmitting data, the baseband processing unit 1j-20 generates complex symbols by encoding and modulating a transmission bit stream. In addition, when receiving data, the baseband processing unit 1j-20 restores a received bit stream through demodulation and decoding of the baseband signal provided from the RF processing unit 1j-10. For example, in the case of the OFDM scheme, when transmitting data, the baseband processing unit 1j-20 generates complex symbols by encoding and modulating a transmission bit stream, mapping the complex symbols to subcarriers, and then IFFT OFDM symbols are configured through calculation and CP insertion. In addition, when receiving data, the baseband processing unit 1j-20 divides the baseband signal provided from the RF processing unit 1j-10 in units of OFDM symbols, and reconstructs signals mapped to subcarriers through FFT operation. After that, the received bit stream is restored through demodulation and decoding. The baseband processing unit 1j-20 and the RF processing unit 1j-10 transmit and receive signals as described above. Accordingly, the baseband processing unit 1j-20 and the RF processing unit 1j-10 may be referred to as a transmission unit, a reception unit, a transmission/reception unit, a communication unit, or a wireless communication unit.

The communication unit 1j-30 provides an interface for performing communication with other nodes in the network.

The storage unit 1j-40 stores data such as a basic program, an application program, and setting information for the operation of the main station. In particular, the storage unit 1j-40 may store information on bearers allocated to the connected terminal, measurement results reported from the connected terminal, and the like. In addition, the storage unit 1j-40 may store information that is a criterion for determining whether to provide multiple connections to the terminal or stop. In addition, the storage unit 1j-40 provides stored data according to the request of the control unit 1j-50.

The control unit 1j-50 controls overall operations of the main station. For example, the control unit 1j-50 transmits and receives signals through the baseband processing unit 1j-20 and the RF processing unit 1j-10 or through the backhaul communication unit 1j-30. Also, the control unit 1j-50 writes and reads data in the storage unit 1j-40. To this end, the control unit 1j-50 may include at least one processor.

Claims (1)

In the control signal processing method in a wireless communication system,
Receiving a first control signal transmitted from a base station;
Processing the received first control signal; And
And transmitting a second control signal generated based on the processing to the base station.

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