WO2016159634A1 - Method for reconfiguring wireless bearer and device thereof - Google Patents

Abstract

The present invention relates to a technology by which a base station transmits, at a radio access network (RAN) level, user plane data by adding a wireless local area network (WLAN) connection to a terminal in which a wireless connection is set. Particularly, the present invention relates to a method and a device for configuring or reconfiguring a wireless data bearer for transmitting user plane data. Specifically, the present invention provides a method and a device, and the method by which a terminal reconfigures a wireless bearer comprises the steps of: receiving, from a base station, an upper layer signaling including information for changing a data wireless bearer type for a specific wireless bearer configured to receive downlink data by using only a WLAN wireless resource; performing a packet data convergence protocol (PDCP) data recovery procedure in a PDCP entity on the basis of the information for changing the data wireless bearer type for the specific wireless bearer; and performing a reordering procedure for the specific wireless bearer in the PDCP entity.

Description

Radio bearer reconfiguration method and apparatus

The present invention relates to a technique for transmitting user plane data by adding a WLAN connection to a terminal where a base station establishes a wireless connection at a radio access network (RAN) level. In particular, the present invention relates to a method and apparatus for configuring or reconfiguring a radio data bearer for transmitting user plane data.

As communication systems have evolved, consumers, such as businesses and individuals, have used a wide variety of wireless terminals. Mobile communication systems such as LTE (Long Term Evolution) and LTE-Advanced of the current 3GPP series are high-speed and large-capacity communication systems that can transmit and receive various data such as video and wireless data beyond voice-oriented services. The development of technology capable of transferring large amounts of data is required. As a method for transmitting a large amount of data, data can be efficiently transmitted using a plurality of cells.

However, there is a limitation in providing a base station to a plurality of terminals that transmit a large amount of data using limited frequency resources. In other words, securing a frequency resource that can be used exclusively by a specific operator has a problem of high cost.

On the other hand, the unlicensed frequency band that can not be used exclusively by a specific operator or a specific communication system can be shared by multiple operators or communication systems. For example, WLAN technology represented by Wi-Fi provides data transmission / reception services using frequency resources of the unlicensed band.

Therefore, the mobile communication system also requires a study on the technology for transmitting and receiving data with the terminal using a corresponding Wi-Fi access point (AP). In particular, when the base station transmits and receives data to and from the terminal using the radio resources of the WLAN and the base station radio resources, a study on a specific procedure and method for this is required.

SUMMARY OF THE INVENTION The present invention devised in this background provides a specific method and apparatus for a base station to add / modify / release / change a radio bearer using at least one of a WLAN radio resource and a base station radio resource.

The present invention also provides a specific method and apparatus for reconfiguring a radio bearer using a WLAN radio resource to a radio bearer using a base station radio resource. Another object of the present invention is to provide a specific method and apparatus for reconfiguring a radio bearer using a base station radio resource to a radio bearer using a WLAN radio resource.

In order to solve the above problems, the present invention provides a method for a UE to reconfigure a radio bearer, the terminal comprising: data for a specific radio bearer configured to receive downlink data using only a wireless local area network (WLAN) radio resource from a base station; A PDCP data recovery procedure is performed in a Packet Data Convergence Protocol (PDCP) entity based on receiving a higher layer signaling including information for changing a radio bearer type and information for changing a data radio bearer type for a specific radio bearer. And performing a reordering procedure for the specific radio bearer in a PDCP entity.

In addition, the present invention provides a method for a terminal reconfiguring a radio bearer, the higher layer signaling including information for changing the data radio bearer type for a specific radio bearer configured to receive downlink data using only the base station radio resources from the base station Initiating a reordering procedure for the particular radio bearer in the Packet Data Convergence Protocol (PDCP) entity based on the receiving and information for changing the data radio bearer type for the particular radio bearer. do.

In addition, the present invention provides a method for a base station to reconfigure a radio bearer of the terminal, information for changing the data radio bearer type for a specific radio bearer configured to receive downlink data using only a wireless local area network (WLAN) radio resource; PDCP SDUs / PDUs (PDCP Service) that have not been verified to be successfully delivered from the PDCP entity based on the step of transmitting higher layer signaling, including a packet data convergence protocol (PDCP) status report from the terminal, and a PDCP status report from the terminal; Data Unit / Protocol Data Unit) provides a method comprising the step of retransmitting.

The present invention also provides information for changing a data radio bearer type for a specific radio bearer configured to receive downlink data using only a wireless local area network (WLAN) radio resource from a base station in a terminal for reconfiguring a radio bearer. A PDCP data recovery procedure is performed in a Packet Data Convergence Protocol (PDCP) entity based on information of changing a data radio bearer type for a specific radio bearer and a receiver that receives higher layer signaling. Provided is a terminal device including a control unit for performing a reordering procedure for a bearer.

In addition, the present invention is a terminal for reconfiguring a radio bearer, receiving a higher layer signaling including information for changing the data radio bearer type for a specific radio bearer configured to receive the downlink data using only the base station radio resources from the base station It provides a terminal device including a receiver and a control unit for initiating a reordering procedure for the specific radio bearer in the Packet Data Convergence Protocol (PDCP) entity based on information for changing the data radio bearer type for the specific radio bearer. .

The present invention also provides a base station for reconfiguring a radio bearer of a terminal, comprising information for changing a data radio bearer type for a specific radio bearer configured to receive downlink data using only a wireless local area network (WLAN) radio resource. PDCP SDUs / PDUs (PDCP Service Data Units) that have not been confirmed to be successfully delivered by the PDCP entity based on a PDCP status report and a receiver that receives a PDCP (Packet Data Convergence Protocol) status report from a transmitter and a terminal for transmitting higher layer signaling. Provides a base station apparatus including a control unit for retransmitting the / Protocol Data Unit.

According to the present invention described above, it provides an effect that the base station can dynamically transmit and receive data with the terminal using the WLAN radio resources.

In addition, the present invention provides a specific method for reconfiguring a terminal and a radio bearer in transmitting user plane data by adding a WLAN radio resource in addition to the base station radio resource to reduce the lossless data transmission effect of the radio bearer mapped to the AM RLC. to provide.

1 is a diagram illustrating a 2C solution structure in a dual connectivity situation.

2 exemplarily illustrates a 3C solution structure in a dual connectivity situation.

3 exemplarily illustrates a 1A solution structure in a dual connectivity situation.

4 is a view for explaining the operation of the terminal according to an embodiment of the present invention.

5 is a view for explaining the operation of the base station according to another embodiment of the present invention.

6 is a view for explaining the operation of the terminal according to another embodiment of the present invention.

7 is a view for explaining a terminal configuration according to another embodiment of the present invention.

8 is a view for explaining the configuration of a base station according to another embodiment of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail through exemplary drawings. In adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are assigned to the same components as much as possible even though they are shown in different drawings. In addition, in describing the present invention, when it is determined that the detailed description of the related well-known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

In the present specification, the MTC terminal may mean a terminal supporting low cost (or low complexity) or a terminal supporting coverage enhancement. In the present specification, the MTC terminal may mean a terminal supporting low cost (or low complexity) and coverage enhancement. Alternatively, in the present specification, the MTC terminal may mean a terminal defined in a specific category for supporting low cost (or low complexity) and / or coverage enhancement.

In other words, in the present specification, the MTC terminal may mean a newly defined 3GPP Release 13 low cost (or low complexity) UE category / type for performing LTE-based MTC related operations. Alternatively, in the present specification, the MTC terminal supports an enhanced coverage compared to the existing LTE coverage, or UE category / type defined in the existing 3GPP Release 12 or less that supports low power consumption, or newly defined Release-13 low cost (or low). complexity) can mean UE category / type.

The wireless communication system in the present invention is widely deployed to provide various communication services such as voice, packet data, and the like. The wireless communication system includes a user equipment (UE) and a base station (base station, BS, or eNB). In the present specification, a user terminal is a generic concept meaning a terminal in wireless communication. In addition, user equipment (UE) in WCDMA, LTE, and HSPA, as well as mobile station (MS) in GSM, user terminal (UT), and SS It should be interpreted as a concept that includes a subscriber station, a wireless device, and the like.

A base station or a cell generally refers to a station that communicates with a user terminal, and includes a Node-B, an evolved Node-B, an Sector, a Site, and a BTS. Other terms such as a base transceiver system, an access point, a relay node, a remote radio head (RRH), a radio unit (RU), and a small cell may be called.

In other words, in the present specification, a base station or a cell is a generic meaning indicating some areas or functions covered by a base station controller (BSC) in CDMA, a Node-B in WCDMA, an eNB or a sector (site) in LTE, and the like. It should be interpreted as, and it is meant to cover all the various coverage areas such as megacell, macrocell, microcell, picocell, femtocell and relay node, RRH, RU, small cell communication range.

Since the various cells listed above have a base station for controlling each cell, the base station may be interpreted in two senses. i) the device providing the megacell, the macrocell, the microcell, the picocell, the femtocell, the small cell in relation to the wireless area, or ii) the wireless area itself. In i) all devices which provide a given wireless area are controlled by the same entity or interact with each other to cooperatively configure the wireless area to direct the base station. The eNB, RRH, antenna, RU, LPN, point, transmit / receive point, transmit point, receive point, and the like, according to the configuration of the radio region, become an embodiment of the base station. In ii), the base station may indicate the radio area itself to receive or transmit a signal from the viewpoint of the user terminal or the position of a neighboring base station.

Therefore, megacells, macrocells, microcells, picocells, femtocells, small cells, RRHs, antennas, RUs, low power nodes (LPNs), points, eNBs, transmit / receive points, transmit points, and receive points are collectively referred to as base stations. do.

In the present specification, the user terminal and the base station are two transmitting and receiving entities used to implement the technology or technical idea described in this specification in a comprehensive sense and are not limited by the terms or words specifically referred to. The user terminal and the base station are two types of uplink or downlink transmitting / receiving subjects used to implement the technology or the technical idea described in the present invention, and are used in a generic sense and are not limited by the terms or words specifically referred to. Here, the uplink (Uplink, UL, or uplink) refers to a method for transmitting and receiving data to the base station by the user terminal, the downlink (Downlink, DL, or downlink) means to transmit and receive data to the user terminal by the base station It means the way.

There is no limitation on the multiple access scheme applied to the wireless communication system. Various multiple access techniques such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), OFDM-FDMA, OFDM-TDMA, OFDM-CDMA Can be used. One embodiment of the present invention can be applied to resource allocation in the fields of asynchronous wireless communication evolving to LTE and LTE-Advanced through GSM, WCDMA, HSPA, and synchronous wireless communication evolving to CDMA, CDMA-2000 and UMB. The present invention should not be construed as being limited or limited to a specific wireless communication field, but should be construed as including all technical fields to which the spirit of the present invention can be applied.

The uplink transmission and the downlink transmission may use a time division duplex (TDD) scheme that is transmitted using different times, or may use a frequency division duplex (FDD) scheme that is transmitted using different frequencies.

In addition, in systems such as LTE and LTE-Advanced, a standard is configured by configuring uplink and downlink based on one carrier or a pair of carriers. The uplink and the downlink include a Physical Downlink Control CHannel (PDCCH), a Physical Control Format Indicator CHannel (PCFICH), a Physical Hybrid ARQ Indicator CHannel (PHICH), a Physical Uplink Control CHannel (PUCCH), an Enhanced Physical Downlink Control CHannel (EPDCCH), and the like. Control information is transmitted through the same control channel, and data is configured by a data channel such as a physical downlink shared channel (PDSCH) and a physical uplink shared channel (PUSCH).

On the other hand, control information may also be transmitted using an enhanced PDCCH (EPDCCH or extended PDCCH).

In the present specification, a cell means a component carrier having a coverage of a signal transmitted from a transmission / reception point or a signal transmitted from a transmission point or a transmission / reception point, and the transmission / reception point itself. Can be.

A wireless communication system to which embodiments are applied may be a coordinated multi-point transmission / reception system (CoMP system) or a coordinated multi-antenna transmission scheme in which two or more transmission / reception points cooperate to transmit a signal. antenna transmission system), a cooperative multi-cell communication system. The CoMP system may include at least two multiple transmission / reception points and terminals.

The multiple transmit / receive point is at least one having a base station or a macro cell (hereinafter referred to as an eNB) and a high transmission power or a low transmission power in a macro cell region, which is wired controlled by an optical cable or an optical fiber to the eNB. May be RRH.

In the following, downlink refers to a communication or communication path from a multiple transmission / reception point to a terminal, and uplink refers to a communication or communication path from a terminal to multiple transmission / reception points. In downlink, a transmitter may be part of multiple transmission / reception points, and a receiver may be part of a terminal. In uplink, a transmitter may be part of a terminal, and a receiver may be part of multiple transmission / reception points.

Hereinafter, a situation in which a signal is transmitted and received through a channel such as a PUCCH, a PUSCH, a PDCCH, an EPDCCH, and a PDSCH may be expressed in the form of 'sending and receiving a PUCCH, a PUSCH, a PDCCH, an EPDCCH, and a PDSCH.'

In addition, hereinafter, a description of transmitting or receiving a PDCCH or transmitting or receiving a signal through the PDCCH may be used as a meaning including transmitting or receiving an EPDCCH or transmitting or receiving a signal through the EPDCCH.

That is, the physical downlink control channel described below may mean PDCCH or EPDCCH, and may also be used to include both PDCCH and EPDCCH.

In addition, for convenience of description, the EPDCCH, which is an embodiment of the present invention, may be applied to the portion described as the PDCCH, and the EPDCCH may be applied to the portion described as the EPDCCH as an embodiment of the present invention.

Meanwhile, higher layer signaling described below includes RRC signaling for transmitting RRC information including an RRC parameter.

The eNB performs downlink transmission to the terminals. The eNB includes downlink control information and an uplink data channel (eg, a physical downlink shared channel (PDSCH), which is a primary physical channel for unicast transmission, and scheduling required to receive the PDSCH. For example, a physical downlink control channel (PDCCH) for transmitting scheduling grant information for transmission on a physical uplink shared channel (PUSCH) may be transmitted. Hereinafter, the transmission and reception of signals through each channel will be described in the form of transmission and reception of the corresponding channel.

The WLAN carrier in the present specification refers to a radio resource of a WLAN and may be described in various terms as necessary, such as a WLAN radio link, a WLAN radio, a WLAN radio resource, or a WLAN radio network. However, hereinafter, a WLAN radio link, a WLAN radio, a WLAN carrier, or a WLAN radio network will be described as WLAN radio resources, and a bearer using WLAN radio resources will be described as WLAN bearers. Also, the WLAN termination herein refers to a logical WLAN network node. For example, it may be a WLAN AP or a WLAN AC. The WLAN termination may be a WLAN network node, such as an existing WLAN AP or an existing WLAN AC, or may be a WLAN network node with additional functionality for WLAN merge transmission to an existing WLAN AP or an existing WLAN AC. The WLAN termination may be implemented as an independent entity or as a functional entity included in another entity. Hereinafter, the WLAN network node will be described as WLAN end point or WLAN AP as necessary. In this specification, radio resources provided by the base station eNB are described as base station radio resources, base station carriers, or E-UTRAN carriers, and a bearer using the base station radio resources is described as base station bearers.

3GPP / WLAN interworking technology provides RAN assisted WLAN interworking functionality. The E-UTRAN may help terminal-based two-way traffic steering between the E-UTRAN and the WLAN for terminals in the RRC_IDLE and RRC_CONNECTED states.

The E-UTRAN provides the assistance parameter to the terminal through broadcast signaling or dedicated RRC signaling. The RAN help parameters include at least one of an E-UTRAN signal strength threshold, a WLAN channel utilization threshold, a WLAN backhaul data rate threshold, a WLAN signal strength (or WLAN signal strength threshold, eg BeaconRSSI threshold) and an offload preference indicator. It may include one. In addition, the E-UTRAN may provide a list of WLAN identifiers to the terminal through broadcast signaling.

In order to determine traffic steering between the E-UTRAN and the WLAN specified in the 3GPP TS 23.402 Architecture enhancements for non-3GPP accesses document, the terminal selects an access network selection and traffic control rule defined in TS 36.304. RAN assistance parameters may be used to evaluate the traffic steering rules or ANDSF policies defined in the TS 24.312 document.

When the access network selection and traffic steering rules defined in the TS 36.304 document are satisfied (fulfilled), the terminal may indicate this to an upper layer of an access stratum (AS).

When the terminal applies the access network selection and traffic control rules, the terminal performs traffic control in APN granularity between the E-UTRAN and the WLAN. As such, the RAN assisted WLAN interworking function provides only a method in which the E-UTRAN and the WLAN are built and stand alone.

Compared to Rel-12 RAN assisted WLAN interworking, the need for LTE WLAN integration capabilities to allow for tighter integration at the RAN level has also increased. As described above, Rel-12 RAN assisted WLAN interworking was only possible for E-UTRAN and WLAN to operate independently in APN units. Accordingly, in transmitting UE user plane data, the E-UTRAN adds a WLAN carrier as one carrier in the E-UTRAN at the RAN level in consideration of the radio state and mobility of the UE, and thus the E-UTRAN carrier and / or WLAN. The carrier could not be configured to be used simultaneously. Alternatively, when the UE transmits user plane data belonging to a specific bearer, the E-UTRAN transmits a WLAN carrier to the UE at the RAN level in consideration of the radio state and mobility of the UE while maintaining the E-UTRAN carrier. Configured to add like one carrier and could not transmit over E-UTRAN carrier and / or WLAN carrier.

To address this, the E-UTRAN adds a WLAN carrier as one carrier in the E-UTRAN at the RAN level to transmit user plane data over the E-UTRAN carrier and / or WLAN carrier on the E-UTRAN layer 2. A method of splitting (or splitting or routing) user plane data and a method of interworking user plane data may be considered. For example, a method of interworking with the user plane data separation method based on 2C and 3C of the dual connectivity solution may be applied. Dual Connectivity Solutions 2C and 3C are the solutions presented in the 3GPP Dual Connectivity section, described in more detail below.

1 is a diagram illustrating a 2C solution structure in a dual connectivity situation.

For example, a structure for adding and configuring a WLAN radio resource in the terminal is similar to the dual connectivity 2C solution, and transmits data to be transmitted through a WLAN carrier in conjunction with a WLAN AP in a PDCP entity in association with a WLAN AP and peers the PDCP entity. Can be configured to receive. In the 2C solution structure, the PDCP entity of the master base station (MeNB) is connected with the RLC entity of the secondary base station (SeNB).

2 exemplarily illustrates a 3C solution structure in a dual connectivity situation.

As another example, a structure for adding and configuring a WLAN radio resource in a terminal is similar to a dual connectivity 3C solution, and separates and transmits data to be transmitted through an E-UTRAN carrier and / or data to be transmitted through a WLAN carrier in a PDCP entity, and peering. The received PDCP entity can receive (or merge) it. In the 3C solution structure, the PDCP entity of the master base station (MeNB) is connected to the RLC entity of the master base station and the RLC entity of the secondary base station, and performs routing functions in the PDCP entity.

3 exemplarily illustrates a 1A solution structure in a dual connectivity situation.

As another example, consider a 1A solution architecture in a dual connectivity situation. In 1A structure, the PDCP entity of each base station is connected with the RLC entity in the base station.

However, in order to use the WLAN carrier at the RAN level while the E-UTRAN establishes a radio connection (eg, RRC connection) with the E-UTRAN carrier in the terminal, an interaction with the WLAN AP is required. This can be quite different from dual connectivity operation with secondary base stations using the same E-UTRAN technology. For example, WLAN carriers are not provided with the RLC functionality provided by conventional dual connectivity. Accordingly, the base station needs an operation for adding, modifying, or releasing a terminal and a radio bearer (or a data radio bearer (hereinafter, referred to as a radio bearer)) by adding a WLAN carrier, but a specific method is not described. Did. That is, configuration / reconfiguration operations such as adding, modifying, changing, and releasing a radio bearer involve detailed operations of each layer 2 entity to which they are associated. Therefore, it is necessary to define the efficient operation of each layer2 object. However, no specific method has been disclosed.

An object of the present invention is to provide a radio bearer configuration or reconfiguration method for the base station to add / modify / release / change the terminal and the radio bearer by adding a WLAN carrier. In addition, an object of the present invention is to provide efficient operation of each layer 2 entity associated with an operation such as adding, modifying, changing, or releasing a radio bearer.

The present invention may be provided in a scenario where a base station and a WLAN AP are non-co-located. In a scenario where the base station and the WLAN AP are non-co-located, the base station and the WLAN AP may be connected or established through a non-ideal backhaul or near-ideal backhaul or an ideal backhaul. In addition, the present invention may be provided in a scenario in which a base station and a WLAN AP are co-located.

In order for an E-UTRAN to add WLAN radio resources to a terminal at the RAN level as one carrier and to transmit and receive user plane data using the E-UTRAN carrier and the WLAN carrier, a protocol structure and operation of each detailed layer must be provided. .

E-UTRAN adds a WLAN radio resource or WLAN carrier as one carrier logically or conceptually configured by the UE and the base station adding functions / objects for data transmission through the WLAN carrier in addition to the existing E-UTRAN cell. It shows.

In the present invention, the E-UTRAN is indicated for convenience of description and may mean LTE / LTE-Advanced / arbitrary 3GPP radio access or base station.

In order for the E-UTRAN to transmit user plane data in units of radio bearers through the E-UTRAN carrier or the WLAN carrier by adding WLAN radio resources to the UE at the RAN level as one carrier in the E-UTRAN, User plane data may be split (or split or routing) or interworked on the sublayer.

For example, similar to the dual connectivity 2C solution described above, the PDCP entity may transmit data to be transmitted through the WLAN carrier in association with the WLAN AP and allow the peered PDCP entity to receive it. For simplicity, hereinafter, similar to the dual connectivity 2C solution, the PDCP entity transmits data to be transmitted through the WLAN carrier in association with the WLAN AP and marks the bearer receiving the peered PDCP entity as the WLAN bearer. This is for convenience of description and other terms meaning the concept may be used.

The WLAN bearer may be used for uplink data transmission and downlink data transmission. Alternatively, the WLAN bearer may be used for downlink data transmission. In this case, uplink data may be transmitted through an E-UTRAN carrier. Alternatively, the WLAN bearer may be used for uplink data transmission, and the downlink data may be transmitted on the E-UTRAN carrier.

The aforementioned E-UTRAN carrier may mean a bearer using only radio resources of a base station in LTE-WLAN aggregation, and a WLAN bearer may mean bearer using only WLAN radio resources in LTE-WLAN aggregation. The WLAN bearer may change by switching radio resources to be used. That is, the switched WLAN bearer may be switched to use only base station radio resources by using only WLAN radio resources and reconfigured through an upper layer message, or may be switched to use only WLAN radio resources by using only base station radio resources and then reconfigured through an upper layer message. have. That is, the WLAN bearer will be described below using only WLAN radio resources. However, the WLAN bearer is assumed to be a switch bearer that may be changed to use only base station radio resources according to bearer reconfiguration.

Meanwhile, similarly to the dual connectivity 3C solution described above, the PDCP entity separates and transmits data to be transmitted through the E-UTRAN carrier and / or data to be transmitted through the WLAN carrier, and receives (or merges and receives) the peered PDCP entity. can do. For convenience of explanation, hereinafter, similar to the dual connectivity 3C solution, the PDCP entity separates the data to be transmitted through the E-UTRAN carrier and / or the data to be transmitted via the WLAN carrier and transmits the bearer to receive it at the peered PDCP object. It is represented by a bearer (Integration bearer, aggregation bearer, WLAN split bearer). This is for convenience of description and other terms meaning the concept may be used.

The merge bearer may be used for uplink data transmission and downlink data transmission. For example, the downlink data may be configured to be transmitted through the E-UTRAN carrier and the WLAN carrier. The uplink data may be configured to be transmitted through the E-UTRAN carrier and the WLAN carrier.

Alternatively, the merge bearer may be used for downlink data transmission. For example, the downlink data may be transmitted through the E-UTRAN carrier and the WLAN carrier. In this case, uplink data may be transmitted through an E-UTRAN carrier. Alternatively, the merge bearer may allow downlink data to be transmitted on the E-UTRAN carrier and the WLAN carrier. In this case, uplink data may be transmitted through a WLAN carrier.

Alternatively, the merge bearer may be used for uplink data transmission. For example, uplink data may be transmitted through an E-UTRAN carrier and a WLAN carrier. In this case, downlink data may be transmitted through an E-UTRAN carrier. As another example, uplink data may be transmitted through an E-UTRAN carrier and a WLAN carrier. In this case, downlink data may be transmitted through a WLAN carrier.

On the other hand, for a terminal that has established an RRC connection with the base station, the base station may add or configure a WLAN bearer by adding a WLAN carrier.

For example, the terminal that has established the RRC connection may add a new radio bearer as a WLAN bearer through core network signaling. The UE that has established the RRC connection may add a new radio bearer as a merge bearer through core network signaling.

As another example, a radio bearer (E-UTRAN bearer) configured in the terminal that has established the RRC connection may be reconfigured / modified / changed into a WLAN bearer.

As another example, a radio bearer (E-UTRAN bearer) configured in the terminal which has established the RRC connection may be reconfigured / modified / modified as a merge bearer. For convenience of description below, the radio bearer (DRB) configured to transmit through the E-UTRAN carrier or the radio bearer (DRB) transmitted only through the E-UTRAN carrier to the terminal that has established the RRC connection with the base station described above, E Denotes a UTRAN bearer or a base station bearer. This is for convenience of description and other terms meaning the concept may be used.

WLAN bearer addition

When the WLAN bearer is added to the terminal through an RRC connection reconfiguration message, the terminal may perform the following operation.

The terminal configures a PDCP entity. The PDCP entity is configured according to the PDCP configuration information (PDCP-Config).

The terminal establishes an entity for transmitting user plane data through the WLAN carrier. The object is configured according to the information for configuring the set object. Hereinafter, for convenience of description, an entity for transmitting user plane data through a WLAN carrier in a terminal is described as a WLAN entity. This is for convenience of description and other terms meaning the concept may be used.

Merge bearer addition

When the merge bearer is added to the terminal through an RRC connection reconfiguration message, the terminal may perform the following operation.

The terminal sets the PDCP entity. The PDCP entity is configured according to the PDCP configuration information (PDCP-Config).

The terminal sets the RLC entity. The RLC entity is configured according to the RLC configuration information (RLC-Config).

The terminal establishes a WLAN entity. The WLAN entity is configured according to the WLAN entity configuration information.

Hereinafter, the operation of the terminal and the base station according to the present invention will be described with reference to the drawings. In particular, the present invention will be described by dividing a specific radio bearer configured in the terminal and the base station from the E-UTRAN bearer to the WLAN bearer or from the WLAN bearer to the E-UTRAN bearer for each embodiment.

4 is a view for explaining the operation of the terminal according to an embodiment of the present invention.

In a method for reconfiguring a radio bearer, a terminal according to an embodiment of the present invention provides a data radio bearer type for a specific radio bearer configured to receive downlink data using only a wireless local area network (WLAN) radio resource from a base station. Performing a PDCP data recovery procedure on a Packet Data Convergence Protocol (PDCP) entity based on receiving a higher layer signaling including changing information and information on changing a data radio bearer type for a specific radio bearer; and PDCP Performing a reordering procedure for a particular radio bearer at the entity.

Referring to FIG. 4, the terminal includes receiving higher layer signaling including information for changing a data radio bearer type for a specific radio bearer configured to receive downlink data using only WLAN radio resources from a base station (see FIG. S410). The terminal may configure a radio bearer with a base station or a WLAN AP using the WLAN bearer addition or merge bearer addition method described above. In addition, the specific radio bearer further configured in the terminal may be a WLAN bearer using only WLAN radio resources. However, the WLAN bearer according to the present invention may be reconfigured after being changed to the E-UTRAN bearer by higher layer signaling as described above. Meanwhile, the UE may separately configure an E-UTRAN bearer using only base station radio resources.

The terminal may receive data radio bearer type information for a specific radio bearer (for example, a WLAN bearer) configured to receive downlink data using only WLAN radio resources from the base station through higher layer signaling. For example, radio bearer type information about a radio bearer may be included in an information element of an RRC connection reconfiguration message. That is, when the WLAN bearer is configured in the terminal, the radio bearer type information may include information indicating that the corresponding WLAN bearer is a bearer using only WLAN radio resources. However, in order to reconfigure and change the WLAN bearer to the E-UTRAN bearer as in the present invention, the terminal may receive information for changing the radio bearer type for the specific radio bearer from the base station.

For example, the terminal may receive information for changing the information on the radio bearer type of the existing WLAN bearer into information on the radio bearer type indicating the E-UTRAN bearer from the base station. That is, when the radio bearer type information for the specific radio bearer is changed from the existing radio bearer type information, the terminal may recognize that the type of the specific radio bearer is changed.

Meanwhile, the terminal includes performing a PDCP data recovery procedure on a Packet Data Convergence Protocol (PDCP) entity based on information for changing a data radio bearer type for a specific radio bearer (S420). When radio bearer type information for a specific radio bearer configured to receive downlink data using only WLAN radio resources is changed, the terminal may perform a PDCP data recovery procedure in the PDCP entity. For example, the terminal needs to reconfigure the specific radio bearer in order to change the radio bearer type of the specific radio bearer from the WLAN bearer to the E-UTRAN bearer. At this time, in order to prevent data loss or omission of downlink data that has been received using only conventional WLAN radio resources, the PDCP entity must perform a PDCP data recovery procedure.

For example, the PDCP entity may generate a PDCP status report and include the PDCP status report in a PDCP PDU (PDCP Protocol Data Unit) to deliver to the lower layer. That is, the PDCP entity may generate a PDCP status report in the PDCP layer and deliver the PDCP status report, which is created to transmit it to the base station, to a lower layer (eg, an RLC layer or a MAC layer). Through this, when the PDCP data recovery procedure is initiated, the terminal transmits a PDCP status report to the base station to help the base station retransmit the PDCP data when the specific radio bearer is reconfigured. A specific PDCP data recovery operation will be described in more detail with reference to the following embodiments.

In addition, the terminal includes a step of performing a reordering procedure for a specific radio bearer in the PDCP entity (S430). When a specific radio bearer receiving downlink data is changed in type from a WLAN bearer to an E-UTRAN bearer, the UE performs a reordering procedure for the specific radio bearer in the PDCP entity. That is, in transmitting downlink data transmitted from the base station to the terminal using the WLAN radio resource to the terminal using the base station radio resource, in order to transmit data in order, to prevent data loss or loss. In order to do this, the terminal performs a reordering procedure for the received downlink data.

To this end, the terminal may additionally receive information for configuring the reordering timer from the base station, the information for configuring the reordering timer may be received through higher layer signaling.

In addition, when the reordering timer expires, the terminal transmits all PDCP SDUs stored for reordering to the upper layer in the ascending order of the associated COUNT value when the reordering timer expires. That is, similar to the RLC Unacknowledged Mode, when the reordering timer expires periodically, all PDCP SDUs received and stored out of the order are delivered to the upper layer, and downlink data is delivered to the upper layer in order. In addition, the terminal may additionally perform a reordering procedure of the 3GPP TS 36.323 document.

As described above, the terminal may reconfigure a radio bearer configured to receive downlink data using only WLAN radio resources into a radio bearer configured to receive downlink data using only base station radio resources. Also, in order to transmit data in sequence in this process, in order to prevent the loss or loss of downlink data, the PDCP entity reorders downlink data for a specific radio bearer, and reconstructs PDCP data of the base station. To help retransmission, a PDCP status report can be generated and sent to the base station.

In FIG. 5, a method of reconfiguring a specific radio bearer carrying downlink data into a base station bearer will be described again from the base station perspective.

5 is a view for explaining the operation of the base station according to another embodiment of the present invention.

In a method for reconfiguring a radio bearer of a terminal, a base station according to an embodiment of the present invention provides a data radio bearer type for a specific radio bearer configured to receive downlink data using only a wireless local area network (WLAN) radio resource. PDCP SDUs (PDCP) for which delivery success is not confirmed in the PDCP entity on the basis of transmitting a higher layer signaling including information to be changed, receiving a Packet Data Convergence Protocol (PDCP) status report from the terminal, and a PDCP status report. Retransmitting a Service Data Unit (PDCP) or PDCP Protocol Data Unit (PDU).

Referring to FIG. 5, a base station of the present invention provides higher layer signaling including information for changing a data radio bearer type for a specific radio bearer configured to receive downlink data using only a wireless local area network (WLAN) radio resource. It includes the step of transmitting (S610). As described above, the base station may generate and transmit information for changing the data radio bearer type for a specific radio bearer (eg, WLAN bearer) to change the WLAN bearer into an E-UTRAN bearer. For example, the base station may transmit information for changing the data radio bearer type through higher layer signaling, and the higher layer signaling may be an RRC connection reconfiguration message.

Meanwhile, the information for changing the data radio bearer type for a specific radio bearer may further include information for configuring a reordering timer used to perform the reordering procedure of the terminal. The terminal receives the information for configuring the reordering timer to configure the reordering timer, and performs a reordering procedure using the reordering timer when a specific radio bearer is reconfigured.

In addition, the base station includes a step of receiving a Packet Data Convergence Protocol (PDCP) status report from the terminal (S520). When the base station changes the data radio bearer type for a specific radio bearer, the base station receives a PDCP status report of the specific radio bearer from the terminal. When the terminal receives information for changing the data radio bearer type of a specific radio bearer, the terminal generates a PDCP status report as a first PDCP PDU to be transmitted to a lower layer and transmits it to the base station.

In addition, the base station includes the step of retransmitting the PDCP SDU or PDCP PDU that is not confirmed whether the successful delivery in the PDCP entity based on the PDCP status report (S530). The base station performs PDCP data recovery using the PDCP status report and retransmits downlink data to the terminal using only the base station radio resources. For example, the base station retransmits the PDCP PDU transmitted to the terminal using the WLAN radio resource to the terminal using the base station radio resource. That is, as a specific radio bearer is reconfigured, the PDCP PDU whose delivery success is not confirmed to the AM RLC entity is retransmitted to the terminal according to the PDCP data recovery procedure.

Hereinafter, an embodiment of reconfiguring a specific radio bearer (WLAN bearer) using only the WLAN radio resource described above to a specific radio bearer (E-UTRAN bearer) using only base station radio resources will be described in detail again.

WLAN Bearer → Reconfigure / Modify / Change E-UTRAN Bearer

1) PDCP re-establishment

When reconfiguring / modifying / changing the WLAN bearer configured in the terminal through the RRC connection reconfiguration message to the E-UTRAN bearer, the terminal may perform the following operations.

The terminal resets the PDCP entity.

The WLAN entity may perform one or more of the following operations.

When possible, deliver PDCP PDUs to higher layers that can be delivered to the PDCP entity at the receiving end.

-Discard the remaining data on the receiving side.

-The sender discards the data.

Discard the control data.

As described above, when the PDCP reset is performed, the UE transmits or retransmits PDCP SDUs whose successful transmission is not confirmed according to the PDCP reset, for data lost during the radio bearer change process, thereby performing lossless transmission. However, this method must handle complex detailed operations such as header compression protocol reset and security key change, PDCP SDUs transmission or retransmission even for bearer change without change of PDCP entity, which can increase complexity and delay. have. Therefore, in the present invention, as described above, a method of reconfiguring a specific radio bearer without resetting the PDCP entity has been described.

2) PDCP Data Recovery

As in the above-described embodiment of 1), when resetting the PDCP entity, unnecessary operations are performed to increase complexity and cause delays. Accordingly, the present invention describes a method of performing a PDCP data recovery procedure without resetting a PDCP entity. In this case, the PDCP entity may be reconfigured or maintained.

When reconfiguring / modifying / changing the WLAN bearer configured in the terminal through the RRC connection reconfiguration message to the E-UTRAN bearer, the terminal may perform the following operations. The RRC Connection Reconfiguration message for reconfiguring / modifying / changing a WLAN bearer into an E-UTRAN bearer includes information for changing the data radio bearer type. For example, the RRC connection reconfiguration message may include a DRB type in "drb-ToAddModList". If the DRB type of the specific radio bearer is received after being changed from the current type, the terminal may reconfigure the specific radio bearer.

The terminal performs PDCP data recovery previously submitted to the WLAN entity.

The WLAN entity may perform one or more of the following operations.

When possible, deliver PDCP PDUs to higher layers that can be delivered to the PDCP entity at the receiving end.

-Discard the remaining data on the receiving side.

-The sender discards the data.

Discard the control data.

In the prior art, PDCP data recovery performs retransmission for all PDCP PDUs previously submitted to the reset AM RLC entity. Therefore, when changing a WLAN bearer into a WLAN bearer, retransmission must be performed for PDCP PDUs submitted to the WLAN entity before receiving a bearer change message (or before performing PDCP data recovery).

According to PDCP data recovery, if the radio bearer is configured to send a PDCP status report by the upper layer on the uplink, generate a PDCP status report and submit it to the first PDCP PDU for transmission to the lower layer.

 When PDCP data recovery for uplink is performed in the terminal, the base station should perform a reordering function for the corresponding PDCP data. Alternatively, when PDCP data recovery for downlink is performed in the base station, the terminal should perform a reordering function for the corresponding PDCP data.

In the prior art, PDCP data recovery can be performed when a bearer change occurs for a split split bearer in Rel-12 dual connectivity (e.g., when a split bearer changes to a split bearer without a PDCP reset or when a split bearer becomes a MCG without a PDCP reset). Only when changed to bearer).

In addition, in the prior art, the reordering function was performed when the split bearer is configured in the terminal. For example, the UE has a reordering function when the PDCP entity is associated with two AM RLC entities in a dual connectivity situation. In another example, the reordering function was performed when the split bearer changed to the split bearer without PDCP resetting. In addition, the PDCP entity is associated with one AM RLC entity after it was, according to the most recent reconfiguration, associated with two AM RLC entities without performing PDCP re reordering function was used.

Accordingly, the PDCP immediately started the reordering function upon receiving the dual connectivity split bearer configuration message, and applied a reordering method such as RLC UM through the set reordering timer (t-Reordering-r12). That is, all stored PDCP SDU (s) is transferred to the upper layer for reordering. The detailed procedure standardized in TS 36.323 is as follows.

When the reordering timer is completed when the reordering is triggered because PDCU data is not received in order, all PDCP SDUs stored for reordering are delivered to the upper layer in ascending order of the associated COUNT value. (When t-Reordering expires, the UE shall:

deliver to upper layers in ascending order of the associated COUNT value:

all stored PDCP SDU (s) with associated COUNT value (s) less than Reordering_PDCP_RX_COUNT;

-all stored PDCP SDU (s) with consecutively associated COUNT value (s) starting from Reordering_PDCP_RX_COUNT;)

Alternatively, the present invention may be set to perform a reordering procedure if PDCP data recovery is used in case of reconfiguring / modifying / modifying a WLAN bearer into an E-UTRAN bearer. When the specific radio bearer is the downlink, the base station may include information (or information for indicating this) for configuring the reordering timer for this to include in the RRC message to the terminal. If a specific radio bearer is uplink, the base station may perform a reordering function for this.

Alternatively, when the above reordering function is not used, the downlink data reception procedure provided by the PDCP may be used. When not using the above reordering function, for a radio bearer mapped to AM RLC, if not lower layer reconfiguration, the PDCP SDU / PDU received by PDCP is immediately forwarded to the upper layer. That is, when the reordering function is not used, data transmitted through a single radio link can be directly transmitted to the upper layer without reordering the PDCP since the RLC guarantees in-sequence transmission. However, when the above-described reordering function is not used, for a radio bearer mapped to AM RLC, if a lower layer reset occurs, it is related to PDCP reset such as handover, so that reordering is performed in PDCP to perform higher layer. Can be delivered as

Therefore, if PDCP data recovery is used in the case of reconfiguring / modifying / changing the aforementioned WLAN bearer to the E-UTRAN bearer, the UE provides downlink data provided by the conventional PDCP when the aforementioned reordering function is not used. Reordering can be improved to allow for reordering. For example, if the PDCP PDU received by the PDCP entity is due to an E-UTRAN bearer change in the WLAN bearer (or if it is due to the release of the WLAN entity or due to a specific operation of the WLAN entity), then reordering: You can do

elseif received PDCP SN = Last_Submitted_PDCP_RX_SN + 1 or received PDCP SN = Last_Submitted_PDCP_RX_SN-Maximum_PDCP_SN:

-deliver to upper layers in ascending order of the associated COUNT value:

--- all stored PDCP SDU (s) with consecutively associated COUNT value (s) starting from the COUNT value associated with the received PDCP PDU;

set Last_Submitted_PDCP_RX_SN to the PDCP SN of the last PDCP SDU delivered to upper layers;

For another example, if the PDCP PDU received by the PDCP is due to an E-UTRAN bearer change in the WLAN bearer (or because of the release of the WLAN entity or due to a specific operation of the WLAN entity), then reordering is performed as follows. You can do that.

deliver to upper layers in ascending order of the associated COUNT value:

-all stored PDCP SDU (s) with consecutively associated COUNT value (s) starting from the COUNT value associated with the received PDCP PDU;

set Last_Submitted_PDCP_RX_SN to the PDCP SN of the last PDCP SDU delivered to upper layers;

As described above, when the bearer type is changed from the WLAN bearer to the E-UTRAN bearer, the receiving side (for example, the UE in the downlink) performs the PDCP data recovery procedure without resetting the PDCP. The reordering procedure may be performed using the reordering timer on the entity.

In the above, a case of reconfiguring a WLAN bearer into an E-UTRAN bearer has been described. However, the specific radio bearer described above includes a switching function so that the E-UTRAN bearer may be reconfigured as a WLAN bearer. Therefore, a procedure according to the present invention when a specific radio bearer is configured to use only base station radio resources and is reconfigured to use only WLAN radio resources will be described below.

6 is a view for explaining the operation of the terminal according to another embodiment of the present invention.

In a method for reconfiguring a radio bearer, the terminal of the present invention receives higher layer signaling including information for changing data radio bearer type for a specific radio bearer configured to receive downlink data from a base station using only base station radio resources. And initiating a reordering procedure for the specific radio bearer in the Packet Data Convergence Protocol (PDCP) entity based on the information for changing the data radio bearer type for the specific radio bearer.

Referring to FIG. 6, the terminal includes receiving higher layer signaling including information for changing a data radio bearer type for a specific radio bearer configured to receive downlink data using only base station radio resources from the base station (S610). ). As described with reference to FIG. 45, the terminal may receive information for changing a data radio bearer type for a specific radio bearer configured to receive downlink data. However, in this case, in order to reconfigure the E-UTRAN bearer to the WLAN bearer, information for changing the data radio bearer type uses only WLAN radio resources in the radio bearer type for receiving downlink data using the radio bearer using only the base station radio resources. It includes information to change to a radio bearer type for receiving downlink data. In addition, the information for changing the data radio bearer type may be included in the RRC connection reconfiguration message.

The terminal checks the information for changing the data radio bearer type included in the higher layer signaling, and when the type information of the specific radio bearer is changed, performs a procedure for reconfiguring the specific radio bearer.

In addition, the terminal includes the step of initiating a reordering procedure for a specific radio bearer in the Packet Data Convergence Protocol (PDCP) entity based on the information for changing the data radio bearer type for the specific radio bearer (S620). In order to reconfigure a specific radio bearer from the E-UTRAN bearer to the WLAN bearer, the terminal initiates a reordering procedure for the specific radio bearer in the PDCP entity. For example, the terminal counts the PDCP SDU using the reordering timer in the PDCP entity, and when the reordering timer expires, delivers the PDCP SDU to the higher layer.

However, when the E-UTRAN bearer is reconfigured as a WLAN bearer, unlike in FIG. 4, the PDCP entity of the UE may initiate a reordering procedure without performing a PDCP data recovery procedure.

Through this, the UE may reconfigure the E-UTRAN bearer configured to receive the downlink data into the WLAN bearer without unnecessary delay and data loss.

Hereinafter, a specific embodiment of reconfiguring an E-UTRAN bearer into a WLAN bearer is described below.

E-UTRAN bearer → WLAN bearer reconfiguration / modification / change

The E-UTRAN bearer configured in the terminal may be reconfigured / modified / changed into the WLAN bearer through the RRC connection reconfiguration message. To this end, the base station may transmit information to change the data radio bearer type of the E-UTRAN bearer in the RRC connection reconfiguration message to the terminal.

As described above, the conventional WLAN did not provide the same function as the RLC entity of the E-UTRAN. Therefore, when the E-UTRAN bearer is reconfigured / modified / modified to the WLAN bearer, loss may occur in the process of switching the corresponding user plane data from transmission through the E-UTRAN carrier to transmission through the WLAN carrier.

For radio bearers mapped to AM Acknowledgment mode Radio Link Control (RLC), lossless data transmission should be guaranteed even when the E-UTRAN bearer configured in the terminal is reconfigured / modified / modified into a WLAN bearer through an RRC connection reconfiguration message. . To this end, the following embodiments can be used.

1) PDCP re-establishment

When reconfiguring / modifying / changing an E-UTRAN bearer configured in a terminal through an RRC connection reconfiguration message to a WLAN bearer, the terminal may perform the following operations.

The terminal resets the PDCP entity.

The terminal resets the RLC entity.

The terminal establishes a WLAN entity. The WLAN entity is configured or reconfigured according to the WLAN entity configuration information.

If PDCP reconfiguration is requested by a higher layer (eg, RRC), the UE performs one or more of the following operations for a radio bearer mapped to AM RLC.

Reset the header compression protocol for uplink and start with an IR state in U-mode (if configured).

Reset the header compression protocol for downlink and start with NC state in U-mode (if configured).

Apply the ciphering algorithm and key provided by higher layers during the re-establishment procedure.

Process the PDCP Data PDUs that are received from lower layers due to the re-establishment of the lower layers by resetting the lower layer (RLC) for the downlink.

For the uplink, PDCP SNs already in ascending order of the COUNT value associated with the PDCP SDU prior to PDCP reset, from the first PDCP SDU whose successful delivery of that PDCP PDU was not confirmed by the lower layer (e.g. RLC). (From the first PDCP SDU for which the successful delivery of the corresponding PDCP PDU has not been confirmed by lower layers, perform retransmission or transmission of all the PDCP SDUs already associated with PDCP SNs in ascending order of the COUNT values associated to the PDCP SDU prior to the PDCP re-establishment as specified below)

-Perform header compression of PDCP SDUs.

-Encryption of PDCP SDUs is performed through the COUNT value associated with the PDCP SDUs.

-Submit the PDCP Data PDU to the lower layer.

When the RLC reset is requested by the higher layer, the AM RLC entity (or the terminal or the AM RLC entity of the terminal) performs one or more of the following operations.

When possible, RLC SDUs are derived from any byte segment of AMD PDUs whose SN is less than the maximum acceptable receive state variable (VR (MR)). Reassemble, remove RLC headers, and deliver all reassembled RLC SDUs to the higher layer in ascending order of RLC SN from any byte segments of AMD PDUs with SN <VR (MR) in the receiving side, remove RLC headers when doing so and deliver all reassembled RLC SDUs to upper layer in ascending order of the RLC SN, if not delivered before).

Discard the remaining AMD PDUs and byte segments of AMD PDUs in the receiving side.

Discard all RLC SDUs and AMD PDUs in the transmitting side.

Discard all RLC control PDUs.

When the PDCP reset and the RLC reset are performed as described above, even if the UE discards all RLC SDUs and AMD PDUs that the transmitter did not transmit according to the RLC reset, the PDCP SDUs whose successful delivery is not confirmed according to the PDCP reset or Retransmission allows lossless transmission. However, this method must handle complex detailed operations such as header compression protocol reset and security key change, PDCP SDUs transmission or retransmission even for bearer change without change of PDCP entity, which can increase complexity and delay. have.

 Therefore, in the present invention, a reconfiguration method for a specific radio bearer can be performed as follows without resetting PDCP.

2) PDCP Data Recovery

For example, when reconfiguring / modifying / changing an E-UTRAN bearer configured in a terminal through an RRC connection reconfiguration message to a WLAN bearer, the terminal may perform the following operation. In this case, the PDCP entity may be reconfigured or maintained.

The terminal performs PDCP data recovery.

The terminal resets the RLC entity. Or, the terminal reconfigures the RLC entity.

The terminal configures the WLAN entity and configures or reconfigures the WLAN entity according to the WLAN entity configuration information.

As another example, when reconfiguring / modifying / changing an E-UTRAN bearer configured in a terminal through an RRC connection reconfiguration message to a WLAN bearer, the terminal may perform the following operation.

If the PDB configuration information is included in the DRB additional modification configuration information, the PDCP entity is reconfigured according to the PDCP configuration information.

The terminal resets the RLC entity. Or, the terminal reconfigures the RLC entity.

The terminal configures the WLAN entity and configures or reconfigures the WLAN entity according to the WLAN entity configuration information.

If a reset is requested to the RLC entity by the higher layer, the AM RLC entity (or the terminal or the AM RLC entity of the terminal) performs the above-described operation. Therefore, a loss may occur depending on the discarded data (SDUs or PDUs) due to the RLC reset.

To ensure lossless transmission, the UE may perform PDCP data recovery. For a radio bearer mapped to AM RLC for PDCP data recovery, the terminal (or PDCP entity or PDCP entity of the terminal) may perform one or more of the following operations.

Perform retransmission of all previously submitted PDCP PDUs, from the first PDCP PDU for which successful delivery has not been confirmed by the lower layer (e.g., RLC layer), to the AM RLC entity reset in ascending order of associated COUNT value. (Perform retransmission of all the PDCP PDUs previously submitted to re-established AM RLC entity in ascending order of the associated COUNT values from the first PDCP PDU for which the successful delivery has not been confirmed by lower layers).

If the radio bearer is configured to send a PDCP status report on the uplink by the upper layer, generate a status report and submit it to the first PDCP PDU for transmission to the lower layer (if the radio bearer is configured by upper layers to send a PDCP status report in the uplink (statusReportRequired), compile a status report, and submit it to lower layers as the first PDCP PDU for the transmission).

When PDCP data recovery for uplink is performed in the terminal, the base station should perform a reordering function for the corresponding PDCP data. When PDCP data recovery for downlink is performed at the base station, the terminal should perform a reordering function for the corresponding PDCP data.

In the prior art, PDCP data recovery can be performed when a bearer change occurs for a split split bearer in Rel-12 dual connectivity (e.g., when a split bearer changes to a split bearer without a PDCP reset or when a split bearer becomes a MCG without a PDCP reset). Only when changed to bearer).

In addition, in the prior art, the reordering function was performed when the split bearer is configured in the terminal. For example, the UE has a reordering function when the PDCP entity is associated with two AM RLC entities in a dual connectivity situation. In another example, the reordering function was performed when the split bearer changed to the split bearer without PDCP resetting. In addition, the PDCP entity is associated with one AM RLC entity after it was, according to the most recent reconfiguration, associated with two AM RLC entities without performing PDCP re reordering function was used.

Accordingly, the PDCP immediately started the reordering function upon receiving the dual connectivity split bearer configuration message, and applied a reordering method such as RLC UM through the set reordering timer (t-Reordering-r12). That is, all stored PDCP SDU (s) is transferred to the upper layer for reordering. The detailed procedure standardized in TS 36.323 is as follows.

When the reordering timer is completed when the reordering is triggered because PDCU data is not received in order, all PDCP SDUs stored for reordering are delivered to the upper layer in ascending order of the associated COUNT value. (When t-Reordering expires, the UE shall:

deliver to upper layers in ascending order of the associated COUNT value:

all stored PDCP SDU (s) with associated COUNT value (s) less than Reordering_PDCP_RX_COUNT;

-all stored PDCP SDU (s) with consecutively associated COUNT value (s) starting from Reordering_PDCP_RX_COUNT;)

Alternatively, the present invention may be set to perform a reordering procedure if PDCP data recovery is used in case of reconfiguring / modifying / modifying a WLAN bearer into an E-UTRAN bearer. When the specific radio bearer is the downlink, the base station may include information (or information for indicating this) for configuring the reordering timer for this to include in the RRC message to the terminal. If a specific radio bearer is uplink, the base station may perform a reordering function for this.

Alternatively, when the above reordering function is not used, the downlink data reception procedure provided by the PDCP may be used. When not using the above reordering function, for a radio bearer mapped to AM RLC, if not lower layer reconfiguration, the PDCP PDU received by PDCP is immediately forwarded to the higher layer. That is, when the reordering function is not used, data transmitted through a single radio link can be directly transmitted to the upper layer without reordering the PDCP since the RLC guarantees in-sequence transmission. However, when the above-described reordering function is not used, for a radio bearer mapped to AM RLC, if a lower layer reset occurs, it is related to PDCP reset such as handover, so that reordering is performed in PDCP to perform higher layer. Can be delivered as

Therefore, if PDCP data recovery is used in the case of reconfiguring / modifying / changing the aforementioned E-UTRAN bearer into a WLAN bearer, when the UE does not use the above-described conventional reordering function, it receives downlink data provided by the PDCP. You may want to improve the procedure to allow reordering.

For example, if the PDCP SDU or PDCP PDU received by PDCP is due to reconfiguration of a lower layer (or due to WLAN bearer change in the E-UTRAN bearer), reordering may be performed as follows.

elseif received PDCP SN = Last_Submitted_PDCP_RX_SN + 1 or received PDCP SN = Last_Submitted_PDCP_RX_SN-Maximum_PDCP_SN:

-deliver to upper layers in ascending order of the associated COUNT value:

--- all stored PDCP SDU (s) with consecutively associated COUNT value (s) starting from the COUNT value associated with the received PDCP PDU;

set Last_Submitted_PDCP_RX_SN to the PDCP SN of the last PDCP SDU delivered to upper layers;

For another example, if the PDCP SDU or PDCP PDU received by PDCP is due to reconfiguration of the lower layer (or due to WLAN bearer change in the E-UTRAN bearer), the reordering may be performed as follows.

deliver to upper layers in ascending order of the associated COUNT value:

-all stored PDCP SDU (s) with consecutively associated COUNT value (s) starting from the COUNT value associated with the received PDCP PDU;

set Last_Submitted_PDCP_RX_SN to the PDCP SN of the last PDCP SDU delivered to upper layers;

3) Perform transmission or retransmission on the RLC object

For example, when reconfiguring / modifying / changing an E-UTRAN bearer configured in a terminal through an RRC connection reconfiguration message to a WLAN bearer, the terminal may perform the following operation.

If the PDB configuration information is included in the DRB additional modified configuration information, the PDCP entity is reconfigured according to the PDCP configuration information.

If the RB configuration information is included in the DRB additional modified configuration information, the RLC entity is reconfigured according to the RLC configuration information.

The terminal configures the WLAN entity and configures or reconfigures the WLAN entity according to the WLAN entity configuration information.

As another example, when reconfiguring / modifying / changing an E-UTRAN bearer configured in a terminal through an RRC connection reconfiguration message to a WLAN bearer, the terminal may perform the following operation.

For PDCP data (eg PDUs or SDUs) sent on the uplink, PDCP does not trigger retransmission. Or PDCP does not trigger retransmission for PDCU PDUs submitted by the PDCP to the RLC entity.

The RLC entity completes the transmission or retransmission of all pending RLC SDUs or RLC PDUs.

The terminal establishes a WLAN entity. The WLAN entity is configured or reconfigured according to the WLAN entity configuration information.

That is, when the E-UTRAN bearer is reconfigured as a WLAN bearer, the RLC entity may be configured to complete transmission or retransmission without releasing the RLC entity.

On the other hand, for a terminal that has established an RRC connection with the base station, the base station assumes that configuring / reconfiguring a WLAN bearer by adding a WLAN carrier is under E-UTRAN coverage. Accordingly, even though the E-UTRAN bearer configured in the terminal through the RRC connection reconfiguration message is reconfigured / modified / changed into the WLAN bearer, the terminal is in an environment capable of transmitting and receiving data with the base station through the E-UTRAN carrier / cell.

Accordingly, when the UE switches the E-UTRAN bearer to the WLAN bearer, the UE may transmit or retransmit the radio bearer mapped to the AM RLC providing for lossless transmission through the RLC entity.

For example, when reconfiguring / modifying / changing an E-UTRAN bearer into a WLAN bearer, one or more of the following operations may be performed.

For uplink, the RLC entity performs transmission or retransmission for PDCP SDUs / PDUs received from the PDCP entity prior to bearer reconfiguration / modification / change. Alternatively, for the uplink, the RLC entity performs transmission or retransmission for RLC SDUs or RLC PUDs received from the PDCP entity prior to bearer reconfiguration / modification / change. Or, for uplink, the RLC entity performs transmission or retransmission for PDCP PDUs submitted by the PDCP entity before bearer reconfiguration / modification / change.

For uplink, the PDCP entity transmits through the WLAN entity starting from the next PDCP PDU of the PDCP PDUs submitted by the PDCP entity before bearer reconfiguration / modification / modification. Or submit PDCP PDUs to the WLAN entity. Or deliver PDCP PDUs via a WLAN entity.

For downlink, the RLC entity processes the RLC data received from the lower layer.

For downlink, the PDCP entity processes the PDCP data received from the lower layer.

At this time, the RLC entity may be maintained until the WLAN bearer is reconfigured / modified / changed or released. Alternatively, the RLC entity may be maintained until the transmission or retransmission of all PDCP PDUs (or RLC SDUs or RLC PDUs) received from the PDCP entity prior to bearer reconfiguration / modification / modification is completed successfully. Alternatively, the RLC entity may maintain a certain time (timer) so that the transmission or retransmission of all PDCP PDUs received from the PDCP entity can be completed successfully before bearer reconfiguration / modification / change. Alternatively, the RLC entity may be reconfigured or maintained for a fast switch from WLAN bearer to E-UTRAN bearer, or for uplink data transmission of WLAN bearer, or for temporary uplink data transmission.

When reconfiguring / modifying / changing an E-UTRAN bearer to a WLAN bearer, information for instructing the performance of the aforementioned operation and / or related information (eg, reordering timer configuration information) may be included in the RRC message. . Alternatively, when reconfiguring / modifying / changing the E-UTRAN bearer to the WLAN bearer, the above-described operation may be preconfigured to be performed.

4) Perform transmission or retransmission through the WLAN object in the RLC object

For example, when reconfiguring / modifying / changing an E-UTRAN bearer configured in a terminal through an RRC connection reconfiguration message to a WLAN bearer, the terminal may perform the following operation.

If the PDB configuration information is included in the DRB additional modified configuration information, the PDCP entity is reconfigured according to the PDCP configuration information.

If the RB configuration information is included in the DRB additional modified configuration information, the RLC entity is reconfigured according to the RLC configuration information.

The terminal configures the WLAN entity and configures or reconfigures the WLAN entity according to the WLAN entity configuration information.

As another example, when reconfiguring / modifying / changing an E-UTRAN bearer configured in a terminal through an RRC connection reconfiguration message to a WLAN bearer, the terminal may perform the following operation.

If the PDB configuration information is included in the DRB additional modified configuration information, the PDCP entity is reconfigured according to the PDCP configuration information.

Reconfigure the RLC entity (or some function of the RLC entity, eg ARQ or retransmission function), to the WLAN entity (or some function of the WLAN entity, eg ARQ or retransmission function).

As another example, when the E-UTRAN bearer configured in the terminal through the RRC connection reconfiguration message to reconfigure / modify / change to the WLAN bearer, the terminal may perform the following operation.

PDCP does not trigger retransmission for uplink PDCP data (eg, PDUs or SDUs). Or PDCP does not trigger retransmission for PDCU PDUs submitted by the PDCP to the RLC entity.

The RLC entity or WLAN entity completes the transmission or retransmission of all pending RLC SDUs or RLC PDUs.

For example, the RLC entity or WLAN entity may complete the transmission or retransmission of all pending RLC SDUs or RLC PDUs on the WLAN carrier. For another example, the RLC entity or WLAN entity may complete the transmission or retransmission of all pending PDCP PDUs on the WLAN carrier. For another example, for uplink, the RLC entity or WLAN entity performs transmission or retransmission for PDCP PDUs received from PDCP entity prior to bearer reconfiguration / modification / change. Alternatively, for the uplink, the RLC entity or WLAN entity performs transmission or retransmission for RLC SDUs or RLC PUDs received from the PDCP entity prior to bearer reconfiguration / modification / change. Or, for uplink, RLC entity or WLAN entity performs transmission or retransmission for PDCP PDUs submitted by PDCP entity before bearer reconfiguration / modification / change.

On the other hand, it is also necessary to consider the case where a specific radio bearer is reconfigured from WLAN bearer to WLAN bearer without changing the data radio bearer type. In this case, the operation of the terminal and the base station will be described below.

WLAN Bearer → Reconfigure / Modify / Change WLAN Bearer

By changing the WLAN AP / Network / SSID / BSSID / HESSID / Domain Name List, the WLAN bearer can be changed to another WLAN AP / Network / SSID / BSSID / HESSID / through a specific WLAN AP / Network / SSID / BSSID / HESSID / Domain Name List. There may be a case in which it is necessary to reconfigure / modify / change the WLAN bearer through the Domain Name List. In this case, data transferred from the PDCP entity to the corresponding WLAN entity may be lost due to a change of WLAN AP / network / SSID / BSSID / HESSID / Domain Name List. For radio bearers mapped to AM Acknowledgment mode Radio Link Control (RLC), lossless data transmission should be ensured even when a WLAN bearer configured in a terminal is reconfigured / modified / modified into a WLAN bearer through an RRC connection reconfiguration message.

To do this, you can use the following method.

1) PDCP re-establishment

When reconfiguring / modifying / changing a WLAN bearer configured in a terminal through an RRC connection reconfiguration message, the terminal may perform the following operations.

The terminal resets the PDCP entity.

The WLAN entity may perform one or more of the following operations.

When possible, deliver PDCP PDUs to higher layers that can be delivered to the PDCP entity at the receiving end.

-Discard the remaining data on the receiving side.

-The sender discards the data.

Discard the control data.

As described above, when the PDCP reconfiguration is performed, the UE transmits or retransmits PDCP SDUs whose successful transmission is not confirmed according to the PDCP resetting for the data lost during the bearer change process, thereby performing lossless transmission. However, this method must handle complex detailed operations such as header compression protocol reset and security key change, PDCP SDUs transmission or retransmission even for bearer change without change of PDCP entity, which can increase complexity and delay. have.

2) PDCP Data Recovery

The PDCP data recovery operation may be performed while maintaining the PDCP entity reconfiguration or PDCP entity without the PDCP reset described above.

For example, when reconfiguring / modifying / changing a WLAN bearer configured in a terminal through an RRC connection reconfiguration message, the terminal may perform the following operation.

The terminal performs a PDCP data recovery procedure previously submitted to the WLAN entity.

The WLAN entity may perform one or more of the following operations.

When possible, deliver PDCP PDUs to higher layers that can be delivered to the PDCP entity at the receiving end.

-Discard the remaining data on the receiving side.

-The sender discards the data.

Discard the control data.

In the prior art, the PDCP data recovery procedure retransmits all PDCP PDUs previously submitted to the reset AM RLC entity. Therefore, when changing a WLAN bearer into a WLAN bearer, it is necessary to perform retransmission over the new WLAN network for PDCP PDUs submitted to the previous WLAN network before receiving the bearer change message (or before performing PDCP data recovery).

According to the PDCP data recovery procedure, if the radio bearer is configured to send a PDCP status report by the upper layer in the uplink, generate a PDCP status report and submit it to the first PDCP PDU for transmission to the lower layer.

When PDCP data recovery for uplink is performed in the terminal, the base station should perform a reordering function for the corresponding PDCP data. When PDCP data recovery for downlink is performed at the base station, the terminal should perform a reordering function for the corresponding PDCP data.

In the prior art, PDCP data recovery can be performed when a bearer change occurs for a split split bearer in Rel-12 dual connectivity (e.g., when a split bearer changes to a split bearer without a PDCP reset or when a split bearer becomes a MCG without a PDCP reset). Only when changed to bearer).

In addition, in the prior art, the reordering function was performed when the split bearer is configured in the terminal. For example, the UE has a reordering function when the PDCP entity is associated with two AM RLC entities in a dual connectivity situation. In another example, the reordering function was performed when the split bearer changed to the split bearer without PDCP resetting. In addition, the PDCP entity is associated with one AM RLC entity after it was, according to the most recent reconfiguration, associated with two AM RLC entities without performing PDCP re reordering function was used.

Accordingly, the PDCP immediately started the reordering function upon receiving the dual connectivity split bearer configuration message, and applied a reordering method such as RLC UM through the set reordering timer (t-Reordering-r12). That is, all stored PDCP SDU (s) is transferred to the upper layer for reordering.

Therefore, if PDCP data recovery is used in the case of reconfiguring / modifying / modifying the WLAN bearer as the WLAN bearer, the reordering function can be operated together. The base station may instruct the terminal by including information (or information for indicating this) to configure the reordering timer for this in the RRC message. The base station may perform a reordering function for this.

Alternatively, when the above reordering function is not used, the downlink data reception procedure provided by the PDCP may be used. When not using the above reordering function, for a radio bearer mapped to AM RLC, if not lower layer reconfiguration, the PDCP PDU received by PDCP is immediately forwarded to the higher layer. That is, when the above-described reordering function is not used, since RLC guarantees in-sequence delivery, the PDCP can be delivered directly to a higher layer without reordering. However, when the above-described reordering function is not used, for a radio bearer mapped to AM RLC, if a lower layer reset occurs, it is related to PDCP reset such as handover, so that reordering is performed in PDCP to perform higher layer. Can be delivered as However, since the WLAN bearer change does not involve RLC resetting, the downlink data reception procedure provided by the PDCP cannot be used when the reordering function according to the prior art is not used.

Therefore, if PDCP data recovery is used in the case of reconfiguring / modifying / modifying the WLAN bearer as the WLAN bearer, the terminal may improve the downlink data reception procedure provided by the conventional PDCP when the reordering function is not used. You may want to reorder.

For example, if the PDCP SDU or PDCP PDU received by PDCP is due to a WLAN bearer change in a WLAN bearer (or because of a release of a WLAN entity or due to a specific operation of a WLAN entity), then reordering: You can do

elseif received PDCP SN = Last_Submitted_PDCP_RX_SN + 1 or received PDCP SN = Last_Submitted_PDCP_RX_SN-Maximum_PDCP_SN:

-deliver to upper layers in ascending order of the associated COUNT value:

--- all stored PDCP SDU (s) with consecutively associated COUNT value (s) starting from the COUNT value associated with the received PDCP PDU;

set Last_Submitted_PDCP_RX_SN to the PDCP SN of the last PDCP SDU delivered to upper layers;

For another example, if the PDCP SDU or PDCP PDU received by PDCP is due to a WLAN bearer change in the WLAN bearer (or due to the release of a WLAN entity or due to a specific operation of the WLAN entity), then reordering: You can do

deliver to upper layers in ascending order of the associated COUNT value:

-all stored PDCP SDU (s) with consecutively associated COUNT value (s) starting from the COUNT value associated with the received PDCP PDU;

set Last_Submitted_PDCP_RX_SN to the PDCP SN of the last PDCP SDU delivered to upper layers;

As described above, in the present invention, when a terminal and a base station transmit and receive data through a specific radio bearer, there is an effect of specifically presenting a reconfiguration method according to bearer type information or WLAN network change of the specific radio bearer. In particular, in the procedure of changing the E-UTRAN bearer into a WLAN bearer and the procedure of changing the WLAN bearer into an E-UTRAN bearer, it is performed without PDCP resetting to provide an effect of suppressing unnecessary delay and data retransmission. In addition, lossless data transmission and reception are possible when reconfiguring a specific radio bearer.

A terminal and a base station apparatus capable of performing all the above-described operations of the present invention will be briefly described again with reference to the drawings.

7 is a view for explaining a terminal configuration according to another embodiment of the present invention.

Referring to FIG. 7, a terminal 700 reconfiguring a radio bearer may change a data radio bearer type for a specific radio bearer configured to receive downlink data using only a wireless local area network (WLAN) radio resource from a base station. The PDCP data recovery procedure is performed in the PDCP entity based on the receiver 730 that receives higher layer signaling including the information and the information for changing the data radio bearer type for the specific radio bearer. The controller 710 performs a reordering procedure for the specific radio bearer in the entity.

The receiver 730 may receive an RRC connection reconfiguration message from the base station including information for changing the data radio bearer type. Information for changing the data radio bearer type for a specific radio bearer is from a radio bearer type for receiving downlink data using only WLAN radio resources to a radio bearer type for receiving downlink data using only base station radio resources. It may contain information to change. or,

Meanwhile, the receiver 730 may receive higher layer signaling including information for changing a data radio bearer type for a specific radio bearer configured to receive downlink data using only base station radio resources. In this case, information for changing the data radio bearer type for a specific radio bearer is downlinked using only a wireless local area network (WLAN) radio resource in a radio bearer type that receives downlink data using a base station radio resource only. It may also include information for changing to a radio bearer type for receiving link data.

Meanwhile, the receiver 730 may further receive information for configuring a reordering timer used to perform a reordering procedure in a PDCP entity, and may receive information for configuring a timer through higher layer signaling. have.

When the reordering timer expires, the controller 710 may transfer all PDCP SDUs stored for reordering to an upper layer in ascending order of the associated COUNT value when the reordering timer expires.

In addition, in performing a PDCP data recovery procedure, the controller 710 may generate a PDCP status report and include the PDCP status report in a PDCP PDU (PDCP Protocol Data Unit) to deliver it to a lower layer.

In addition, the controller 710 performs both the above-described PDCP data recovery procedure and reordering procedure when reconfiguring the WLAN bearer into the E-UTRAN bearer, and the above-described PDCP data when reconfiguring the E-UTRAN bearer into the WLAN bearer. It is also possible to perform only a reordering procedure without a recovery procedure.

In addition, the receiver 730 receives downlink control information, data, and a message from a base station through a corresponding channel. In addition, the controller 710 controls the overall operation of the terminal according to the configuration / reconfiguration for the base station to add / modify / release / change the terminal and the radio bearer by the base station required to perform the present invention described above.

The transmitter 720 transmits uplink control information, data, and a message to a base station through a corresponding channel.

8 is a view for explaining the configuration of a base station according to another embodiment of the present invention.

Referring to FIG. 8, the base station 800 transmits higher layer signaling including information for changing data radio bearer type for a specific radio bearer configured to receive downlink data using only WLAN radio resources. PDCP Protocol Data Unit (PDCP PDU) or PDCP SDU (PDCP SDU) that has not been confirmed to be successfully delivered from the PDCP entity based on the receiver 830 and the PDCP status report that receive a PDCP (Packet Data Convergence Protocol) status report from the terminal And a control unit 810 for retransmitting the data unit.

The transmitter 820 includes information for changing a data radio bearer type for a specific radio bearer. Here, the information for changing the data radio bearer type for a specific radio bearer is a radio bearer that receives downlink data using only base station radio resources in a radio bearer type that receives downlink data using a WLAN radio resource only. It may include information for changing to a type. Alternatively, the information for changing the data radio bearer type for a specific radio bearer is a radio bearer that receives downlink data using only WLAN radio resources in a radio bearer type that receives downlink data using a base station radio resource only. It may include information for changing to a type.

In addition, the transmitter 820 may transmit information for configuring a reordering timer used for the terminal to perform the reordering procedure to the terminal. In this case, information for configuring the reordering timer may be transmitted through higher layer signaling (eg, an RRC message).

In addition, the control unit 810 controls the overall operation of the base station according to the configuration / reconfiguration for the base station to add / modify / release / change the terminal and the radio bearer by the base station required to perform the present invention described above .

The transmitter 820 and the receiver 830 are used to transmit and receive signals, messages, and data necessary for carrying out the present invention.

The standard contents or standard documents mentioned in the above embodiments are omitted to simplify the description of the specification and form a part of the present specification. Therefore, the addition of the contents of the standard and part of the standard documents to the specification or the description in the claims should be interpreted as falling within the scope of the present invention.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and changes without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

CROSS-REFERENCE TO RELATED APPLICATION

This patent application is related to the patent application No. 10-2015-0046974 filed in Korea on April 02, 2015 and the patent application No. 10-2016-0037352 filed in Korea on March 29, 2016. Priority is claimed under section (a) (35 USC § 119 (a)), all of which is incorporated by reference in this patent application. In addition, if this patent application claims priority for the same reason for countries other than the United States, all its contents are incorporated into this patent application by reference.

Claims (20)

In a method for a terminal reconfiguring a radio bearer, Receiving a higher layer signaling including information for changing a data radio bearer type for a specific radio bearer configured to receive downlink data using only a wireless local area network (WLAN) radio resource from a base station; Performing a PDCP data recovery procedure on a Packet Data Convergence Protocol (PDCP) entity based on information for changing a data radio bearer type for the specific radio bearer; And Performing a reordering procedure for the specific radio bearer at the PDCP entity. The method of claim 1, Information for changing the data radio bearer type for the specific radio bearer, And changing the specific radio bearer from a radio bearer type for receiving downlink data using only the WLAN radio resources to a radio bearer type for receiving downlink data using only the base station radio resources. . The method of claim 1, Performing the PDCP data recovery procedure, Generating a PDCP status report and including the PDCP status report in a PDCP PDU (PDCP Protocol Data Unit) to deliver to a lower layer. The method of claim 1, The higher layer signaling, And information for configuring a reordering timer used to perform a reordering procedure in the PDCP entity. The method of claim 1, Performing the reordering procedure, And when the reordering timer expires, delivering a PDCP Service Data Unit (PDCP SDU) of all the downlink data stored for reordering to a higher layer. In a method for a terminal reconfiguring a radio bearer, Receiving upper layer signaling including information for changing a data radio bearer type for a specific radio bearer configured to receive downlink data using only base station radio resources from the base station; And Initiating a reordering procedure for the particular radio bearer in the Packet Data Convergence Protocol (PDCP) entity based on the information for changing the data radio bearer type for the particular radio bearer. The method of claim 6, Information for changing the data radio bearer type for the specific radio bearer, And including information for changing the specific radio bearer from a radio bearer type for receiving downlink data using only the base station radio resources to a radio bearer type for receiving downlink data using only a wireless local area network (WLAN) radio resource. Characterized in that the method. In the method for the base station to reconfigure the radio bearer of the terminal, Transmitting upper layer signaling including information for changing a data radio bearer type for a specific radio bearer configured to receive downlink data using only a wireless local area network (WLAN) radio resource; Receiving a PDCP (Packet Data Convergence Protocol) status report from the terminal; And Retransmitting a PDCP protocol data unit (PDCP PDU) or a PDCP service data unit (PDCP SDU) for which delivery was not confirmed in a PDCP entity based on the PDCP status report. The method of claim 8, Information for changing the data radio bearer type for the specific radio bearer, And changing the specific radio bearer from a radio bearer type for receiving downlink data using only the WLAN radio resources to a radio bearer type for receiving downlink data using only the base station radio resources. . The method of claim 8, Information for changing the data radio bearer type for the specific radio bearer, The method of claim 1, further comprising information for configuring a reordering timer used to perform the reordering procedure of the terminal. In the terminal for reconfiguring a radio bearer, A receiving unit for receiving upper layer signaling including information for changing a data radio bearer type for a specific radio bearer configured to receive downlink data using only a wireless local area network (WLAN) radio resource from a base station; And Based on the information for changing the data radio bearer type for the specific radio bearer, a PDCP data recovery procedure is performed in a Packet Data Convergence Protocol (PDCP) entity, and a reordering procedure for the specific radio bearer is performed in the PDCP entity. Terminal comprising a control unit. The method of claim 11, Information for changing the data radio bearer type for the specific radio bearer, And a terminal for changing the specific radio bearer from a radio bearer type for receiving downlink data using only the WLAN radio resource to a radio bearer type for receiving downlink data using only the base station radio resources. . The method of claim 11, The control unit for performing the PDCP data recovery procedure, And generating a PDCP status report and including the PDCP status report in a PDCP PDU (PDCP Protocol Data Unit) to deliver it to a lower layer. The method of claim 11, The higher layer signaling, The terminal further comprises information for configuring a reordering timer used to perform a reordering procedure in the PDCP entity. The method of claim 11, The control unit for performing the reordering procedure, And when the reordering timer expires, delivering a PDCP Service Data Unit (PDCP SDU) of all the downlink data stored for reordering to a higher layer. In the terminal for reconfiguring a radio bearer, A receiver for receiving higher layer signaling including information for changing a data radio bearer type for a specific radio bearer configured to receive downlink data using only base station radio resources from the base station; And And a controller for initiating a reordering procedure for the specific radio bearer in the packet data convergence protocol (PDCP) entity based on information for changing a data radio bearer type for the specific radio bearer. The method of claim 16, Information for changing the data radio bearer type for the specific radio bearer, And including information for changing the specific radio bearer from a radio bearer type for receiving downlink data using only the base station radio resources to a radio bearer type for receiving downlink data using only a wireless local area network (WLAN) radio resource. Terminal, characterized in that. In the base station for reconfiguring a radio bearer of the terminal, A transmitter for transmitting higher layer signaling including information for changing a data radio bearer type for a specific radio bearer configured to receive downlink data using only a wireless local area network (WLAN) radio resource; Receiving unit for receiving a PDCP (Packet Data Convergence Protocol) status report from the terminal; And And a control unit for retransmitting a PDCP protocol data unit (PDCP PDU) or a PDCP service data unit (PDCP SDU) whose delivery success is not confirmed in a PDCP entity based on the PDCP status report. The method of claim 18, Information for changing the data radio bearer type for the specific radio bearer, And a base station for changing the specific radio bearer from a radio bearer type for receiving downlink data using only the WLAN radio resource to a radio bearer type for receiving downlink data using only the base station radio resources. . The method of claim 18, Information for changing the data radio bearer type for the specific radio bearer, The base station further comprises information for configuring a reordering timer used to perform the reordering procedure of the terminal.

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