KR20150050956A - Method and apparatus for configuring drx parameter in wireless communication system using dual connectivity - Google Patents

Abstract

Provided is a method for configuring parameters for discontinuous reception in a wireless communication system using a dual connection and an apparatus of the same. The method for a master base station to configure discontinuous reception (DRX) parameters may include the steps of: determining a first DRX parameter for a terminal which is dually connected to the master base station and a secondary base station; transmitting the information related to the first DRX parameter to the secondary base station; receiving a second DRX parameter, from the secondary base station which is determined based on the information related to the first DRX parameter; and transmitting the received second DRX parameter to the terminal.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a parameter setting method and apparatus for discontinuous reception in a wireless communication system using a dual-

The present invention relates to a method and apparatus for configuring DRX (Discontinuous Reception) parameters for discontinuous reception when a UE is configured with dual connectivity with at least two Node Bs in a wireless communication system.

In a wireless communication system, a terminal can perform wireless communication through two or more base stations among the base stations constituting at least one serving cell. This is called dual connectivity. In other words, a dual connection is an operation in which a terminal set to an RRC connection state with at least two different network points consume radio resources provided by the network points can do. At least two or more different network points may be physically or logically divided into a plurality of base stations. One of them is a master eNB (MeNB), and the remaining base stations are a secondary base station (SenB) .

In the dual connection, each base station transmits downlink data through a bearer configured for one terminal and receives uplink data. At this time, one bearer may be configured through one base station, or may be configured through two or more different base stations. Also, in the dual connection, each base station may have at least one or more serving cells configured, and each serving cell may be operated in an active or inactive state. At this time, a primary serving cell (PCell) is configured in the master base station and a secondary serving cell (SCell: Secondary (serving) cell) is configured in the secondary base station. ) May be configured. Here, carrier aggregation is a technique for efficiently using a fragmented small band, in which one base station bundles a plurality of physically continuous or non-continuous bands in the frequency domain to form a logically large band So as to have the same effect as using a band.

On the other hand, the power consumption by the receiving circuit of a general terminal is not negligible, and the operation of the receiving circuit continuously increases the power consumption of the terminal. Accordingly, the wireless communication system supports Discontinuous Reception (DRX) to reduce the power consumption of the UE. DRX refers to a function that allows the UE to stop monitoring the PDCCH during a predetermined period of time (i.e., a sleep period or an inactive period), and the UE is activated with a predetermined periodicity in the DRX mode Repeat the time and the inactivity time. Here, the active time means a time for monitoring the PDCCH, and the inactivity time means a time for stopping the monitoring of the PDCCH.

In a case where a discontinuous reception (DRX: Discontinuous Reception) is configured in a terminal in a dual connection, the terminal performs a separate DRX operation for each base station and the parameter for the DRX operation is also configured separately for each base station. Accordingly, if the inactivity time for the master base station and the inactivity time for the secondary base station do not overlap each other even if the DRX is configured in the terminal in the dual connection, the terminal always monitors the PDCCH for the master base station or the secondary base station in the DRX mode, Is not reduced.

Therefore, a method of synchronizing the inactivity time (or active time) with the master base station and the inactivity time (or active time) with the secondary base station in the DRX configuration for the terminal in the dual connection is required.

SUMMARY OF THE INVENTION The present invention provides a parameter configuration method and apparatus for discontinuous reception in a wireless communication system using a dual connection scheme.

Another aspect of the present invention is to provide a DRX parameter configuration method and apparatus capable of reducing the total activation time of the UE when the DRX is configured in a terminal having a dual connection.

Another aspect of the present invention is to provide a DRX parameter configuration method and apparatus for synchronizing an active time for a master base station and an active time for a secondary base station in a DRX configuration of a terminal having a dual connection.

According to an aspect of the present invention, a method of configuring a discontinuous reception (DRX) parameter by a master base station includes determining a first DRX parameter for a terminal connected to the master base station and the secondary base station, Information from the secondary base station to the secondary base station, receiving from the secondary base station a second DRX parameter determined based on the information related to the first DRX parameter, and transmitting the received second DRX parameter to the terminal .

According to another aspect of the present invention, a method for configuring a DRX parameter by a secondary base station comprises receiving from the master base station at least one candidate DRX parameter set configured for a terminal that is dual-connected through a master base station and the secondary base station, Selecting a candidate DRX parameter set to be configured for the UE from among one candidate DRX parameter set and transmitting an index of the selected candidate DRX parameter set or the selected candidate DRX parameter set to the master base station .

In the DRX configuration of the terminal having the dual connection in the wireless communication system, the activation time for the master base station and the activation time for the secondary base station can be synchronized, so that the battery consumption of the terminal can be reduced as the total activation time of the terminal is reduced .

1 is a diagram showing a network structure of a wireless communication system.
2 is a block diagram illustrating a wireless protocol structure for a user plane.
3 is a block diagram illustrating a wireless protocol structure for a control plane.
4 is a diagram showing a structure of a bearer service in a wireless communication system.
5 is a diagram showing a dual connection situation of a terminal.
6 is a diagram illustrating a user plane structure for a dual connection.
7 and 8 are diagrams illustrating a protocol structure of base stations in downlink transmission of user plane data.
9 is a diagram for explaining discontinuous reception applied to the present invention.
10 to 12 are signal flow diagrams illustrating a method of configuring DRX parameters through cooperation between a master base station and a secondary base station according to an embodiment of the present invention.
13 is a flowchart illustrating an operation of a master base station according to an embodiment of the present invention.
14 is a flowchart illustrating an operation of a secondary base station according to an embodiment of the present invention.
15 is a flowchart illustrating an operation of a terminal according to an embodiment of the present invention.
16 is a block diagram illustrating a master base station, a secondary base station, and a terminal according to an embodiment of the present invention.

Hereinafter, the contents related to the present invention will be described in detail with reference to exemplary drawings and embodiments, together with the contents of the present invention. It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference symbols as possible even if they are shown in different drawings. In the following description of the embodiments of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present disclosure rather unclear.

In addition, the present invention will be described with respect to a wireless communication network. The work performed in the wireless communication network may be performed in a process of controlling a network and transmitting data by a system (e.g., a base station) Work can be done at a terminal connected to the network.

1 is a diagram showing a network structure of a wireless communication system.

FIG. 1 shows a network structure of an evolved-universal mobile telecommunications system (E-UMTS) system as an example of a wireless communication system. The E-UMTS system may be an Evolved-UMTS Terrestrial Radio Access (E-UTRA) or a Long Term Evolution (LTE) or an LTE-A (advanced) system. The wireless communication system can be classified into a Code Division Multiple Access (CDMA), a Time Division Multiple Access (TDMA), a Frequency Division Multiple Access (FDMA), an Orthogonal Frequency Division Multiple Access (OFDMA), a Single Carrier- , OFDM-TDMA, and OFDM-CDMA.

Referring to FIG. 1, an Evolved-UMTS Terrestrial Radio Access Network (E-UTRAN) includes a Base Station (BS) providing a control plane (CP) and a user plane (UP) (eNB: evolved NodeB, 20).

The terminal 10 may be fixed or mobile and may be referred to by other terms such as a mobile station (MS), an advanced MS (MS), a user terminal (UT), a subscriber station (SS) have.

The base station 20 generally refers to a station that communicates with the terminal 10 and includes a base station (BS), a base transceiver system (BTS), an access point, a femto-eNB, A pico-eNB, a home eNB, a relay, or the like. The base stations 20 are physically connected to each other through an optical cable or a DSL (digital subscriber line), and can exchange signals and messages with each other through the Xn interface. In FIG. 1, for example, the base stations 20 are connected through an X2 interface.

In the following, the description of the physical connection is omitted and the logical connection is described. As shown in FIG. 1, the base station 20 is connected to an evolved packet core (EPC) 30 through an S1 interface. More specifically, the base station 20 is connected to an MME (Mobility Management Entity) through an S1-MME interface and is connected to an S-GW (Serving Gateway) through an S1-U interface. The base station 20 exchanges context information of the terminal 10 and information for supporting the mobility of the terminal 10 through the S1-MME interface with the MME. And sends and receives data to be served to the S-GW and each terminal 10 through the S1-U interface.

Although not shown in FIG. 1, the EPC 30 includes an MME, an S-GW, and a packet data network-gateway (P-GW). The MME has information on the connection information of the terminal 10 and the capability of the terminal 10. This information is mainly used for managing the mobility of the terminal 10. [ The S-GW is a gateway having an E-UTRAN as an end point, and the P-GW is a gateway having a PDN (Packet Data Network) as an end point.

The E-UTRAN and the EPC 30 may be combined to form an EPS (Evolved Packet System). The traffic flow from the wireless link to the base station 20 to the PDN that connects the terminal 10 to the service entity (Internet Protocol).

On the other hand, a wireless interface between the terminal 10 and the base station 20 is referred to as a "Uu interface ". The layers of the radio interface protocol between the terminal 10 and the network are divided into a first layer L1 defined by a 3rd Generation Partnership Project (3GPP) series wireless communication system (UMTS, LTE, LTE-Advanced, etc.) A second layer L2 and a third layer L3. Among them, the physical layer belonging to the first layer provides an information transfer service using a physical channel, and the RRC (Radio Resource Control) layer located at the third layer exchanges RRC messages, (10) and the network.

FIG. 2 is a block diagram illustrating a radio protocol architecture for a user plane, and FIG. 3 is a block diagram illustrating a radio protocol structure for a control plane. The user plane is a protocol stack for transmitting user data, and the control plane is a protocol stack for transmitting control signals.

Referring to FIGS. 2 and 3, a physical layer (PHY (physical layer) of a terminal and a base station provide an information transfer service to an upper layer using a physical channel, respectively. The physical layer is connected to a medium access control (MAC) layer, which is an upper layer, through a transport channel. The data is transmitted between the MAC layer and the physical layer through a transmission channel. The transport channel is classified according to how the data is transmitted over the air interface. Further, data is transmitted through physical channels between different physical layers (i.e., between the physical layer of the terminal and the base station). The physical channel can be modulated by an Orthogonal Frequency Division Multiplexing (OFDM) scheme, and uses time, frequency, and space generated by a plurality of antennas as radio resources.

For example, a physical downlink control channel (PDCCH) of a physical channel notifies a UE of resource allocation of a paging CHannel (DLH), a downlink shared channel (DL-SCH), and Hybrid Automatic Repeat Request (HARQ) And an uplink scheduling grant informing the UE of the resource allocation of the uplink transmission. The Physical Control Format Indicator CHannel (PCFICH) informs the UE of the number of OFDM symbols used for PDCCHs and is transmitted every subframe. Also, the PHICH (Physical Hybrid ARQ Indicator CHannel) carries HARQ ACK / NAK signals in response to the uplink transmission. Also, the Physical Uplink Control CHannel (PUCCH) carries uplink control information such as HARQ ACK / NAK, scheduling request and CQI for downlink transmission. Also, the Physical Uplink Shared CHannel (PUSCH) carries UL-SCH (Uplink Shared CHannel). If necessary, the PUSCH may include CSI (Channel State Information) information such as HARQ ACK / NACK and CQI according to the setup and request of the base station.

The MAC layer can perform multiplexing or demultiplexing into a transport block provided on a physical channel on a transport channel of a MAC SDU (Service Data Unit) belonging to a logical channel and a mapping between a logical channel and a transport channel. The MAC layer provides service to the Radio Link Control (RLC) layer through a logical channel. The logical channel can be divided into a control channel for transferring control area information and a traffic channel for transferring user area information. For example, there are data transmission or radio resource allocation as services provided from the MAC layer to the upper layer.

The function of the RLC layer includes concatenation, segmentation and reassembly of the RLC SDUs. The RLC layer includes a transparent mode (TM), an unacknowledged mode (UM), and an acknowledged mode (AM) to guarantee various QoSs required by a radio bearer (RB) Acknowledged Mode).

In general, transparent mode is used to set the initial connection.

The unacknowledged mode is for data streaming or real-time data transmission such as Voice over Internet Protocol (VoIP), and is a speed-focused mode rather than a data reliability. On the other hand, the acknowledged mode is a mode that focuses on the reliability of data and is suitable for data transmission which is less sensitive to large data transmission or transmission delay. The base station determines the mode of the RLC in the RB corresponding to each EPS bearer based on the Quality of Service (QoS) information of each EPS bearer connected to the UE and configures the parameters in the RLC so as to satisfy the QoS.

RLC SDUs are supported in various sizes, and may be supported on a byte basis, for example. RLC Protocol Data Units (PDUs) are defined only when a transmission opportunity from a lower layer (eg, the MAC layer) is notified and are passed on to the lower layer. The transmission opportunity may be notified with the size of the total RLC PDUs to be transmitted. In addition, the transmission opportunity and the size of the total RLC PDUs to be transmitted may be separately reported.

The functions of the Packet Data Convergence Protocol (PDCP) layer in the user plane include delivery of user data, header compression and ciphering, and delivery of control plane data and encryption / integrity protection.

Referring to FIG. 3, the RRC layer is responsible for controlling logical channels, transport channels, and physical channels in connection with configuration, re-configuration and release of RBs. A radio bearer (RB) refers to a logical path provided by a first layer (PHY layer) and a second layer (MAC layer, RLC layer, PDCP layer) for data transmission between a UE and a network. The configuration of the RB means a process of defining characteristics of a radio protocol layer and a channel to provide a specific service, and setting each specific parameter and an operation method. RB may be classified into SRB (Signaling RB) and DRB (Data RB). The SRB is used as a path for transmitting the RRC message and the NAS (Non-Access Stratum) message in the control plane, and the DRB is used as a path for transmitting the user data in the user plane.

The non-access stratum (NAS) layer located at the top of the RRC layer performs functions such as session management and mobility management. When there is an RRC connection between the RRC layer of the UE and the RRC layer of the E-UTRAN, the UE is in an RRC connected state. Otherwise, the UE is in an RRC idle state do.

In order for a terminal to transmit user data (e.g., IP packets) to an external Internet network or to receive user data from an external Internet network, it is necessary for the terminal to exist between the mobile communication network entities existing between the terminal and the external Internet network. The resource must be assigned to multiple paths. A path in which resources are allocated between mobile communication network entities and data transmission / reception is possible is called a bearer.

4 is a diagram showing a structure of a bearer service in a wireless communication system.

FIG. 4 shows a path in which an end-to-end service is provided between a terminal and the Internet network. Here, the term end-to-end service refers to a service (UE Bearer) between the UE and the P-GW, a P-GW, and an external bearer to the outside for an Internet network and data service . Here, the external path is a bearer between the P-GW and the Internet network.

When the UE transmits data to the external Internet network, the UE transmits data to the eNB through the RB. Then, the base station transmits the data received from the terminal to the S-GW through the S1 bearer. The S-GW carries the data received from the base station through the S5 / S8 bearer to the P-GW, and finally the data is transmitted to the destination existing in the P-GW and the external internet network through the external bearer.

Likewise, in order for data to be transmitted from the external Internet network to the mobile station, the mobile station can transmit data to the mobile station via the bearers in the reverse direction.

As described above, in the wireless communication system, each bearer is defined for each interface to ensure independence between interfaces. The bearer at each interface will be described in more detail as follows.

The bearer provided by the wireless communication system is collectively referred to as an evolved packet system (EPS) bearer. The EPS bearer is a delivery path established between the UE and the P-GW to transmit IP traffic with a specific QoS. The P-GW may receive IP flows from the Internet or may transmit IP flows over the Internet. Each EPS bearer is set with QoS decision parameters indicating the characteristics of the propagation path. One or more EPS bearers may be configured per UE, and one EPS bearer uniquely represents a concatenation of one E-RAB (E-UTRAN Radio Access Bearer) and one S5 / S8 bearer.

The radio bearer (RB) exists between the UE and the base station and delivers the packets of the EPS bearer. A specific RB has a one-to-one mapping relationship with the corresponding EPS bearer / E-RAB.

The S1 bearer carries the E-RAB packet as a bearer existing between the S-GW and the base station.

The S5 / S8 bearer is the bearer of the S5 / S8 interface. Both S5 and S8 are bearers present at the interface between the S-GW and the P-GW. S5 interface exists when the S-GW and P-GW belong to the same service provider. The S8 interface belongs to the Visited PLMN roaming S-GW and the P- RTI ID = 0.0 > PLMN). ≪ / RTI >

The E-RAB uniquely represents the concatenation of the S1 bearer and its corresponding RB. When there is one E-RAB, a one-to-one mapping is established between the corresponding E-RAB and one EPS bearer. That is, one EPS bearer corresponds to one RB, S1 bearer, and S5 / S8 bearer, respectively. The S1 bearer is the bearer at the interface between the base station and the S-GW.

RB means two kinds of data RB (data radio bearer) and signaling RB (signaling radio bearer). However, in the present invention, RB is a DRB provided in a Uu interface to support a user service . Therefore, the RB that is expressed separately is distinguished from the SRB. RB is a path through which user plane data is transmitted, and SRB is a path through which control plane data such as an RRC layer and a NAS control message are transmitted. There is a one-to-one mapping between RB, E-RAB and EPS bearer. The base station maps DRBs and S1 bearers to one-to-one and stores them in order to generate a DRB that bundles both uplink and downlink. The S-GW maps the S1 bearer to the S5 / S8 bearer one-to-one and stores it in order to create the S1 bearer and the S5 / S8 bearer that bind both the uplink and downlink.

EPS bearer types include a default bearer and a dedicated bearer. When a terminal accesses a wireless communication network, the terminal allocates an IP address and generates a PDN connection. At this time, a default EPS bearer is generated. That is, the default bearer is first created when a new PDN connection is created. If a user uses a service (eg, the Internet) via a default bearer and uses a service (eg, VoD, etc.) that is not properly provided with QoS as the default bearer, A dedicated bearer is created. In this case, the dedicated bearer can be set to a different QoS from the bearer that has already been set. The QoS decision parameters applied to the dedicated bearer are provided by the Policy and Charging Rule Function (PCRF). When generating the dedicated bearer, the PCRF can receive the subscription information of the user from the Subscriber Profile Repository (SPR) and determine QoS determination parameters. Up to 15 dedicated bearers may be created, for example, up to 15, and four of the 15 dedicated bearers are not used in the LTE system. Therefore, up to 11 dedicated bearers can be generated in the LTE system.

The EPS bearer includes QoS Class Identifier (QCI) and Allocation and Retention Priority (ARP) as basic QoS decision parameters. EPS bearer is divided into GBR (Guaranteed Bit Rate) bearer and non-GBR bearer according to QCI resource type. The default bearer is always set to a non-GBR bearer, and the dedicated bearer can be set to a GBR or non-GBR bearer. In addition to QCI and ARP, the GBR type bearer has GBR and MBR (Maximum Bit Rate) as QoS decision parameters. After QoS defined by the wireless communication system as a whole is defined as an EPS bearer, QoS is determined for each interface. Each interface establishes a bearer according to the QoS it should provide.

5 is a diagram illustrating an example of a dual connection situation of a terminal.

5, when the terminal 550 enters the overlaid area of the service area of the macro cell F2 in the master base station 500 and the service area of the small cell F1 in the secondary base station 510, Fig.

In this case, in order to support the additional data service through the small cell F1 in the secondary base station 510 while maintaining the existing wireless connection and the data service connection through the macro cell F2 in the master base station 500, And establishes a dual connection to the terminal 550. Accordingly, the user data arriving at the master base station 500 can be transmitted to the terminal through the secondary base station 510. Specifically, the F2 frequency band is allocated to the master base station 500, and the F1 frequency band is allocated to the secondary base station 510. [ The terminal 550 can receive the service from the master base station 500 through the frequency band F2 and receive the service from the secondary base station 510 via the frequency band F1. In the above example, the master base station 500 uses the F2 frequency band and the secondary base station 510 uses the F1 frequency band. However, the present invention is not limited to this, and the master base station 500 and the secondary base station 510 510) may use the same F1 or F2 frequency band.

6 is a view showing a structure of a user plane for a double connection.

The dual connection consists of an arbitrary terminal, a master base station (MeNB) and at least one secondary base station (SeNB). The double connection can be divided into three options as shown in FIG. 6 depending on how the user plane data is divided. In Fig. 6, the concept of the above three options for downlink transmission of user plane data is shown as an example.

The first option is when the S1-U interface has an end point not only in the master base station but also in the secondary base station. In this case, each of the base stations MeNB and SeNB transmits downlink data through an EPS bearer (EPS bearer # 1 for the master base station and EPS bearer # 2 for the secondary base station) configured for one UE. Since the user plane data is splitted in the core network (CN), this is called a CN split.

The second option is when the S1-U interface has endpoints only in the master base station, but the bearer does not differentiate and only one bearer is mapped to each base station.

The third option is when the S1-U interface has endpoints only at the master base station and the diversifier differentiates into multiple base stations. In this case, since the bearer is differentiated, it is called a bear split. The bearer split is divided into two flows (or more flows) because one bearer is differentiated into a plurality of base stations. We call bearer splits as multi-flow, multiple-node (eNB) transmission, inter-eNB carrier aggregation, etc. in that information is transmitted through multiple flows. Also.

On the other hand, if the end point of the S1-U interface is the master base station (i.e., the second or third option) in terms of the protocol structure, the protocol layer in the secondary base station must support the segmentation or refinement process. This is because the physical interface and subdivision processes are closely related to each other, and when using non-ideal backhaul, the subdivision or subdivision process must be the same as the node transmitting the RLC PDU. Therefore, considering the protocol structures for dual connection in the RLC layer and above, the following is considered.

1. It is the case that the PDCP layer exists independently in each base station. This is also referred to as an independent PDCP type. In this case, each base station can use the operation of the existing LTE layer 2 protocol in the bearer as it is. This can be applied to both the first option and the third option.

2. An RLC layer exists independently in each base station. This is also referred to as an independent RLC type. In this case, the S1-U interface makes the master base station an end point, and the PDCP layer exists only in the master base station. In the case of the bearer split (third option), the RLC layer is separated in both the network and the UE side, and there exists an independent RLC bearer for each RLC layer.

3. The RLC layer is divided into the 'master RLC' layer of the master base station and the 'slave RLC' layer of the secondary base station. This is also referred to as master-slave RLC type. In this case, the S1-U interface has a master base station as an end point. In the master base station, a part of the PDCP layer and the RLC layer (the master RLC layer) exists and the secondary base station has a part of the RLC layer (the slave RLC layer). In the UE, there is only one RLC layer forming a pair with the master RLC layer and the slave RLC layer.

Accordingly, the double connection can be configured as shown in FIG. 7 or FIG. 8 by a combination of the above-described options and types.

7 and 8 are diagrams illustrating a protocol structure of base stations in downlink transmission of user plane data.

First, referring to FIG. 7, the S1-U interface has an end point not only in the master base station but also in the secondary base station, and the PDCP layer exists independently in each base station (in the case of the independent PDCP type). In this case, the PDCP layer, the RLC layer and the MAC layer exist in the master base station and the secondary base station, respectively, and each base station transmits downlink data through each EPS bearer configured for the terminal.

In this case, the master base station does not need to buffer or process packets transmitted by the secondary base station, and has the advantage that there is little or no impact on the RDCP / RLC and GTP-U / UDP / IP. In addition, there is no need for a backhaul link between the master base station and the secondary base station, and there is no need to control the flow between the master base station and the secondary base station, so that the master base station does not need to route all the traffic. And can support local break-out and content caching.

Referring to FIG. 8, the S1-U interface has an end point only in the master base station and is bearer split, and the RLC layer exists independently in each base station (in the case of the independent RLC type). In this case, the master base station has the PDCP layer, the RLC layer, and the MAC layer, and only the RLC layer and the MAC layer exist in the secondary base station. The PDCP layer, the RLC layer, and the MAC layer of the master base station are separated into bearer levels, and one PDCP layer is connected to one of the RLC layers of the master base station and is connected to the RLC layer of the secondary base station via the Xn interface.

In this case, there is no security effect that the mobility of the secondary base station is hidden in the core network, encryption is required in the master base station, and data forwarding between the secondary base stations is not necessary when the secondary base station is changed. Also, the master base station can transfer the RLC processing to the secondary base station, utilize the radio resources through the master base station and the secondary base station for the same bearer when there is no influence on the RLC, and if possible, Since the master base station can be used, there is an advantage that the requirements for the mobility of the secondary base station are small.

On the other hand, CA (Carrier Aggregation) is a technique for efficiently using a fragmented small band, in which one base station is divided into a plurality of physically continuous or non-continuous multiple bands in the frequency domain So as to have the same effect as using a logically large band. When the terminal forms a CA, the terminal has one RRC connection with the network. This is the same even when a dual connection is configured. When establishing, re-establishing, or handing over an RRC connection, a particular serving cell provides non-access stratum (NAS) mobility information (e.g., TAI: Tracking Area ID). Hereinafter, the specific serving cell is referred to as a primary cell (PCell), and the serving cell other than the specific serving cell is referred to as a secondary serving cell (SCell).

The main serving cell may be composed of a DL Primary PCC (Downlink Primary Component Carrier) and a UL PCC (Uplink Primary Component Carrier). On the other hand, the secondary serving cells may be configured in the form of a serving cell set together with the primary serving cell according to the UE capability of the UE. The secondary serving cell may be composed of only a DL SCC (Downlink Secondary Component Carrier) or a pair with a UL SCC (Uplink Secondary Component Carrier).

Thus, the serving cell set is composed of one main serving cell and at least one secondary serving cell. The main serving cell can be changed only through a handover procedure and is used for PUCCH transmission. The main serving cell can not transition to the inactive state, but the secondary serving cell can be transitioned to the inactive state.

The RRC connection re-establishment procedure is triggered when it experiences a Radio Link Failure (RLF) in the main serving cell. However, the RLF of the serving cell is not triggered.

Meanwhile, adding, removing, or reconfiguring the secondary serving cell in the serving cell set is accomplished through an RRC connection reconfiguration procedure, which is dedicated signaling. Therefore, when adding a new serving cell to a serving cell set, the RRC connection reconfiguration message also includes system information for the new serving cell. Therefore, in the case of the auxiliary serving cell, no monitoring operation for changing the system information is required.

The RRC connection reconfiguration procedure is performed for the purpose of modifying the RRC connection. For example, the RRC connection reconfiguration procedure may include establishing / modifying / releasing the RB, handing over, establishing / modifying / releasing measurements, adding / modifying / For example. NAS dedicated information may be transmitted from the E-UTRAN to the terminal while the RRC connection reconfiguration procedure is performed.

The RRC connection reconfiguration procedure may be initiated when the E-UTRAN is RRC connected to the terminal. When AS security is enabled, mobility control information is included in the RRC connection reconfiguration message, and at least one DRB and SRB2 are established, which is not suspended. In addition, setting of RBs (RBs set during RRC connection establishment in addition to SRB1) and addition of secondary serving cell are also performed when AS security is activated.

The RRC connection reconfiguration message is a message for modifying the RRC connection, and includes measurement configuration information, mobility control information, and radio resource configuration information including dedicated NAS information and security configuration I can carry it. The radio resource configuration information may include RB, MAC main configuration, and physical channel configuration information.

9 is a diagram for explaining discontinuous reception applied to the present invention.

The wireless communication system supports Discontinuous Reception (DRX) to reduce the power consumption of the UE. DRX is a function that allows the UE to stop monitoring the PDCCH for a predetermined period (sleep period or inactive time). As shown in FIG. 9, in the DRX mode, Repeat the time. Here, the active time means a time for monitoring the PDCCH, and the inactivity time means a time for stopping the monitoring of the PDCCH.

The UE generates PDCCHs based on a Cell-Radio Network Temporary Identifier (C-RNTI), a Transmission Power Control (PPC) -PUCCH-RNTI, a TPC-PUSCH-RNTI and a Semi Persistent Scheduling (SPS) Monitoring can be performed. The monitoring of the PDCCH can be controlled by the DRX operation, and the parameter related to the DRX is transmitted to the UE as the RRC signaling. The UE can always receive SI (System Information) -RNTI, P (Paging) -RNTI, etc. in addition to the RNTIs regardless of the DRX operation configured by the RRC message. Here, the remaining PDCCHs other than the PDCCH scrambled with the C-RNTI are received through the common search space of the main serving cell.

If the DRX parameter is configured in the RRC connected state, the UE performs discontinuous monitoring on the PDCCH based on the DRX operation. On the other hand, if the DRX parameter is not configured, the UE performs continuous monitoring of the PDCCH. Here, discontinuous monitoring means that the UE monitors the PDCCH only in a specific subframe, and continuous monitoring means that the UE monitors the PDCCH in all subframes. Meanwhile, when PDCCH monitoring is required in a DRX-independent operation such as a random access procedure, the UE can monitor the PDCCH according to the requirements of the corresponding operation.

The RRC layer manages several timers to control the DRX operation. The timer controlling the DRX operation includes a duration timer (onDurationTimer), a DRX inactivity timer (DRXInactivity Timer), and a DRX retransmission timer (DRXRetransmission Timer). In addition, there are a long DRX cycle (longDRX-Cycle) and a DRX start offset (drxStartOffset) as parameters for controlling the DRX operation. The base station optionally sets a DRX short cycle timer (drxShortCycleTimer) and a short DRX- . In addition, a HARQ round trip time (RTT) timer is defined for each downlink HARQ process.

The DRX start offset is a value defining the subframe at which the DRX cycle begins. The DRX short cycle timer is a timer that defines the number of consecutive subframes for which the UE should follow a short DRX cycle. The HARQ RTT timer is a timer that defines the minimum number of subframes prior to an interval in which a UE is expected to receive a downlink HARQ retransmission.

The duration timer starts when the DRX cycle begins. That is, the start time of the sustain interval timer coincides with the start time of the DRX cycle. The sustain interval timer expires when the value of the sustain interval timer increases by '1' every sub-frame of the PDCCH and the sustain interval timer becomes equal to the preset expiration value. The sustain interval timer is valid until the sustain interval timer value becomes equal to the expiration value.

The DRX inactivity timer is a time for monitoring the PDCCH for successful decoding of the PDCCH to be received from the time of successfully decoding the PDCCH for uplink or downlink user data transmission. The DRX inactivity timer is started or restarted when the UE successfully decodes the PDCCH for the HARQ initial transmission in the PDCCH subframe.

The DRX Retransmission Timer is a timer that operates based on the maximum number of consecutive numbers of PDCCH subframes expected to be DL retransmitted by the UE. The DRX Retransmission Timer starts when the HARQ RTT timer has expired but fails to receive the retransmission data. The UE can monitor the reception of data retransmitted in the HARQ process while the DRX retransmission timer is in progress. The setting of the DRX retransmission timer is defined by the MAC-MainConfig message of the RRC layer.

When the DRX cycle is configured, the UE monitors the PDCCH for the PDCCH subframe during the active time. Here, the PDCCH subframe means a subframe including a PDCCH. The activation time may refer to all the periods in which the UE is awake. For example, the terminal is activated when at least one timer of the above-described persistent interval timer, DRX inactivity timer, and DRX retransmission timer is in progress. Also, it is activated when a scheduling request is sent or pending through the PUCCH, and is activated even when uplink grant for pending HARQ transmission occurs and data exists in the corresponding HARQ buffer. It is also activated when a PDCCH indicating a new transmission to the C-RNTI of the UE is not received after the random access response for the preamble selected by the UE has been successfully received.

A non-active time during a DRX cycle may be referred to as a non-active time. The active time may be referred to as a wake up period, and the inactivity time may be referred to as a sleep period.

If the DRX command MAC control element (DRX command MAC control element) is received in each subframe when the DRX is configured, the terminal stops the DRX inactivity timer and the DRX timer. Also, if the DRX inactivity timer expires or a DRX command MAC control element is received, use a short DRX cycle and start or restart the DRX short cycle timer, or use a long DRX cycle. The terminal uses the long DRX cycle when the DRX short cycle timer expires. If a short DRX cycle or a long DRX cycle is used, the terminal starts a sustain interval timer.

Meanwhile, when the MS performs a handover from the source BS to the target BS, in order to transmit the RRC information of the E-UTRA used in the handover preparation step from the source BS to the target BS, Is used. The following message may be referred to as handover preparation information.

- ASN1START HandoverPreparationInformation :: = SEQUENCE { criticalExtensions CHOICE { c1 CHOICE { handoverPreparationInformation-r8 HandoverPreparationInformation-r8-IEs, spare7 NULL, spare6 NULL, spare5 NULL, spare4 NULL, spare3 NULL, spare2 NULL, spare1 NULL }, criticalExtensionsFuture SEQUENCE {} } } HandoverPreparationInformation-r8-IEs :: = SEQUENCE { ue-RadioAccessCapabilityInfo UE-CapabilityRAT-ContainerList, as-Config AS-Config      OPTIONAL, - Cond HO rrm-Config RRM-Config OPTIONAL, as-Context AS-Context OPTIONAL, - Cond HO nonCriticalExtension HandoverPreparationInformation-v920-IEs OPTIONAL } ... - ASN1STOP

Referring to Table 1, radio resource configuration information required for handover in the E-UTRA is transmitted through the AS-Config field, and the local E-UTRAN context requested by the target base station is transmitted through the AS-Context field.

The AS-Config information element includes information about the RRC configuration at the source base station configurable in the target base station so that the RRC configuration of the target base station can be changed during the handover preparation step. The information on the RRC configuration may be used after the handover is performed or when the RRC connection is reset. Table 2 below shows the AS-Config information element.

- ASN1START AS-Config :: = SEQUENCE { sourceMeasConfig MeasConfig, sourceRadioResourceConfig RadioResourceConfigDedicated, sourceSecurityAlgorithmConfig SecurityAlgorithmConfig, sourceUE-Identity C-RNTI, sourceMasterInformationBlock MasterInformationBlock, sourceSystemInformationBlockType1 SystemInformationBlockType1 (WITH COMPONENTS {..., nonCriticalExtension ABSENT})) sourceSystemInformationBlockType2 SystemInformationBlockType2, antennaInfoCommon AntennaInfoCommon, sourceDl-CarrierFreq ARFCN-ValueEUTRA, ..., [[sourceSystemInformationBlockType1Ext OCTET STRING (CONTAINING SystemInformationBlockType1-v890-IEs) OPTIONAL, sourceOtherConfig-r9                  OtherConfig-r9 ]], [[sourceSCellConfigList-r10 SCellToAddModList-r10 OPTIONAL ]], } AS-Config-v9e0 :: = SEQUENCE { sourceDl-CarrierFreq-v9e0 ARFCN-ValueEUTRA-v9e0 } - ASN1STOP

The antennaInfoCommon field in Table 2 provides information about the number of antenna ports of the source base station. The sourceDL-CarrierFreq field provides the downlink EARFCN parameter of the source base station. The sourceOtherConfig field provides other configuration information of the source base station. The sourceMasterInformationBlock field provides information about the master information block transmitted in the main serving cell of the source base station. The sourceMeasConfig field is included when the handover is triggered and provides measurement configuration information. The sourceRadioResourceConfig field is included when the handover is triggered and provides the radio configuration information of the source base station. The sourceSCellConfigList field provides radio resource configuration information for the serving cells of the source base station. The sourceSecurityAlgorithmConfig field provides information about the algorithm configuration, such as AS integrity protection and AC operations, used at the source base station. The sourceSystemInformationBlockType1 field and the sourceSystemInformationBlockType2 field provide information on the source system information block type (sourceSystemInformationBlockType) transmitted in the main serving cell of the source base station.

Meanwhile, the AS-Context information element is used to transmit the local E-UTRAN context to the target base station. Table 3 below shows the AS-Context information element.

- ASN1START AS-Context :: = SEQUENCE { reestablishmentInfo ReestablishmentInfo OPTIONAL - Cond HO } AS-Context-v1130 :: = SEQUENCE { idc-Indication-r11 OCTET STRING (CONTAINING InDeviceCoexIndication-r11) OPTIONAL, - Cond HO2 mbmsInterestIndication-r11 OCTET STRING (CONTAINING MBMSInterestIndication-r11) OPTIONAL, - Cond HO2 powerPrefIndication-r11 OCTET STRING (CONTAINING UEAssistanceInformation-r11) OPTIONAL, - Cond HO2 ... } - ASN1STOP

In Table 3, the idc-Indication field contains information used to handle IDC problems, and the reestablishmentInfo field contains information required at RRC connection reset. The HO field is a field that is essential for handover in E-UTRA, and the HO2 field is a field that is selectively present in handover in E-UTRA.

Meanwhile, a radio resource specific information element (RadioResourceConfigDedicated information element) is used for setting / modifying / releasing RBs, modifying the MAC main setting, modifying the SPS configuration, and modifying the dedicated physical configuration. Table 4 below shows information elements dedicated to radio resource configuration.

- ASN1START RadioResourceConfigDedicated :: = SEQUENCE {     ... mac-MainConfig CHOICE { explicitValue MAC-MainConfig, defaultValue NULL } OPTIONAL - Cond HO-toEUTRA2 ... } RadioResourceConfigDedicatedSCell-r10 :: = SEQUENCE { - UE specific configuration extensions applicable for an SCELL physicalConfigDedicatedSCell-r10 PhysicalConfigDedicatedSCell-r10 OPTIONAL, - Need ON ..., [[mac-MainConfigSCell-r11 MAC-MainConfigSCell-r11 OPTIONAL - Cond SCellAdd ]] } ... } - ASN1STOP

In Table 4, the mac-MinConfig field can be explicitly signaled or set to the default MAC main configuration. The MAC-mainconfig information element is used to specify the MAC main configuration for signaling and DRB. Table 5 below shows the MAC-mainconfig information element.

- ASN1START MAC-MainConfig :: = SEQUENCE {     ... OPTIONAL, - Need ON DRX-Config DRX-Config OPTIONAL, - Need ON ... MAC-MainConfigSCell-r11 :: = SEQUENCE { stag-Id-r11 STAG-Id-r11 OPTIONAL, - Need OP ... } DRX-Config :: = CHOICE { release NULL, setup SEQUENCE { onDurationTimer ENUMERATED { pSF1, pSF2, pSF3, pSF4, pSF5, pSF6, psf8, psf10, psf20, psf30, psf40, psf50, psf60, psf80, psf100, psf200}, DRx-InactivityTimer ENUMERATED { pSF1, pSF2, pSF3, pSF4, pSF5, pSF6, psf8, psf10, psf20, psf30, psf40, psf50, psf60, psf80, psf100, psf200, psf300, psf500, psf750, psf1280, psf1920, psf2560, psf0-v1020, spare9, spare8, spare7, spare6, spare5, spare4, spare3, spare2, spare1}, DRx-RetransmissionTimer ENUMERATED { psf1, psf2, psf4, psf6, psf8, psf16, psf24, psf33}, longDRX-CycleStartOffset CHOICE { sf10 INTEGER (0..9), sf20 INTEGER (0..19), sf32 INTEGER (0..31), sf40 INTEGER (0..39), sf64 INTEGER (0..63), sf80 INTEGER (0..79), sf128 INTEGER (0..127), sf160 INTEGER (0..159), sf256 INTEGER (0..255), sf320 INTEGER (0..319), sf512 INTEGER (0..511), sf640 INTEGER (0..639), sf1024 INTEGER (0..1023), sf1280 INTEGER (0..1279), sf2048 INTEGER (0..2047), sf2560 INTEGER (0..2559) } shortDRX SEQUENCE {
shortDRX-Cycle ENUMERATED { sf2, sf5, sf8, sf10, sf16, sf20, sf32, sf40, sf64, sf80, sf128, sf160, sf256, sf320, sf512, sf640}, drxShortCycleTimer INTEGER (1..16) } OPTIONAL - Need OR } } DRX-Config-v1130 :: = SEQUENCE { DRX-RetransmissionTimer-v1130 ENUMERATED {psf0-v1130} OPTIONAL, --Need OR longDRX-CycleStartOffset-v1130 CHOICE { sf60-v1130 INTEGER (0..59), sf70-v1130 INTEGER (0..69) } OPTIONAL, --Need OR shortDRX-Cycle-v1130 ENUMERATED {sf4-v1130} OPTIONAL --Need OR } STAG-ToReleaseList-r11 :: = SEQUENCE (SIZE (1..maxSTAG-r11)) OF STAG-Id-r1 STAG-ToAddModList-r11 :: = SEQUENCE (SIZE (1..maxSTAG-r11)) OF STAG-ToAddMod-r11 STAG-ToAddMod-r11 :: = SEQUENCE { stag-Id-r11 STAG-Id-r11, timeAlignmentTimerSTAG-r11 TimeAlignmentTimer,     ... } STAG-Id-r11 :: = INTEGER (1..maxSTAG-r11) - ASN1STOP

Referring to Table 5, the DRX configuration information includes an onDurationTimer field for limiting the value of the duration timer, a drx-InactivityTimer field indicating a value of the DRX inactivity timer, and a drx-RetransmissionTimer field indicating a value of the DRX retransmission timer. The DRX configuration information also includes a longDRX-CycleStartOffset field indicating the length of the long DRX cycle and a starting subframe, and a shortDRX field related to the short-term DRX that can be optionally configured. The shortDRX field contains a shortDRX-Cycle subfield that indicates the length of the short DRX cycle and a drxShortCycleTimer subfield that indicates the value of the short-term DRX cycle timer that the terminal consecutive.

The onDurationTimer field may be set to any one of the values of {psf1, psf2, psf3, ... psf200}. psf denotes a PDCCH subframe, and the number after psf denotes the number of PDCCH subframes. That is, psf represents the expiration value of the timer as the number of PDCCH subframes. For example, if the onDurationTimer field = psf1, the duration timer expires after progressing cumulatively to one PDCCH subframe including the subframe in which the DRX cycle started. If the onDurationTimer field = psf4, the duration timer expires after progressing cumulatively to the four PDCCH subframes from the beginning of the DRX cycle.

The drx-InactivityTimer field may be set to any one of the values of {psf1, psf2, psf3, ... psf2560}. For example, if the drx-InactivityTimer field = psf3, the DRX inactivity timer expires cumulatively up to three PDCCH subframes including the subframe at the time of driving, and then expires. The drx-RetransmissionTimer field may be set to one of the values of {psf1, psf2, psf4, ... psf33}. For example, if the drx-RetransmissionTimer field = psf4, the DRX Retransmission Timer expires after progressing up to four PDCCH subframes cumulatively including the subframe at the time of being driven.

The longDRX-CycleStartOffset field may be set to one of the values of {sf10, sf20, sf32, sf40, ... sf2560} as the length of the long DRX cycle, and the subframe at which the long DRX cycle starts is the length of the long DRX cycle INTEGER (0..39), ... INTEGER (0..2559)} values corresponding to the values of the values of [ For example, if the longDRX-CycleStartOffset field = sf20, INTEGER (0..19), then one long DRX cycle includes 20 subframes, and the long DRX cycle may be any subframe Can be selected as the long-term DRX cycle start sub-frame.

The shortDRX-Cycle subfield constituting the shortDRX field may be set to any one of the values of {sf2, sf5, sf8, ... sf640}. For example, if the shortDRX-Cycle subfield = sf5, then one short DRX cycle includes five subframes. In addition, the drxShortCycleTimer subfield constituting the shortDRX field may represent any one of the integers 1 to 16. For example, if the drxShortCycleTimer subfield = 3, the short DRX cycle expires three times.

When configuring the DRX, the UE proceeds to the DRX operation using the DRX parameters described above. However, when a terminal having a dual connection established through a master base station and a secondary base station constitutes a DRX, the terminal proceeds to a separate DRX operation for each base station, and the parameter for the DRX operation is also divided do. Therefore, even if the DRX is configured in the terminal having the dual connection, the power consumption is not greatly reduced unless the inactivity time for the master base station and the inactivity time for the secondary base station are overlapped with each other. Therefore, the present disclosure discloses a method for maximizing synchronization between an activation time for a master base station and an activation time for a secondary base station through cooperation between a master base station and a secondary base station in a DRX operation of a terminal having a dual connection. According to this method, the total activation time of the terminal can be reduced.

One method of synchronizing the activation time for each base station of the terminal includes synchronizing the start time of the first sustain interval timer of the master base station and the start time of the second sustain interval timer of the secondary base station. The starting point of the persistent interval timer of each base station can be synchronized by synchronizing the start point of the period of the short DRX cycle or the long DRX cycle. To do this, parameters such as a DRX start offset (drxStartOffset), a short DRX cycle (short DRX-Cycle), a long DRX cycle (longDRX-Cycle) If the DRX start offset value for each base station is set to the same offset value, the subframe at which the duration starts can be equally set for each base station or can be configured as a subset. Further, if the short-term DRX cycle or the long-term DRX cycle value for each base station is set to a multiple relation, the subframe in which the sustain period starts may be set equal to each base station or may be configured as a subset.

Another method of synchronizing the activation time for each base station of the terminal includes minimizing the DRX deactivation timer value. For example, for a service with high delay tolerance based on QoS, minimizing the DRX inactivity timer value can minimize activation time. In general, the service through the secondary base station corresponds to the service with higher delay tolerance than the service through the master base station. Therefore, when configuring the DRX by itself, the secondary base station configures the DRX inactivity timer value for the specific service to a small value when configuring the DRX in a state in which the dual connection with the master base station is configured to be less than the DRX inactivity timer value for the specific service . The reference may be provided by the master base station to the secondary base station as DRX related information.

10 to 12 are signal flow diagrams illustrating a method of configuring DRX parameters through cooperation between a master base station and a secondary base station according to an embodiment of the present invention. Hereinafter, a method of configuring the DRX parameters of the secondary base station for the MS based on the DRX-related information provided by the master BS will be described with reference to FIGS. 10 to 12. FIG.

The first embodiment includes the method disclosed in Fig. Referring to FIG. 10, the master BS determines a DRX parameter for the MS (S1010), and proceeds to the RRC connection reconfiguration procedure for DRX configuration for the MS and the MS (S1020). Then, the already configured DRX-related information is transmitted to the secondary base station (S1030). Here, the DRX related information may be a DRX parameter as shown in FIG. 10, and the DRX parameter may be at least one of a DRX start offset, a short DRX cycle, and a long DRX cycle. In addition, the DRX-related information may include reference information for adjusting the DRX deactivation timer value of the secondary base station based on QoS. The master base station may use an AS-Config message or a message defined in the Xn interface when transmitting the DRX-related information to the secondary base station.

Upon receiving the DRX-related information from the master base station, the secondary base station determines the DRX parameter for the terminal of the secondary base station using the received DRX-related information (S1040), and transmits the determined DRX parameter to the master base station via the Xn or X2 interface (S1050).

The master base station performs an RRC connection reconfiguration procedure for DRX configuration between the secondary base station and the terminal using the DRX parameters received from the secondary base station (S1060). At this time, the master base station does not recognize or interpret the received DRX parameter, and can directly include the received DRX parameter when constructing the RRC connection reconfiguration message.

On the other hand, the master base station may transmit the already determined DRX parameters to the secondary base station not configured for the terminal. In this case, step S1020 is omitted, and the DRX parameter for the terminal of the master base station and the DRX parameter for the terminal of the secondary base station can both be transmitted to the terminal when the RRC connection reconfiguration procedure of step 1060 is performed. Here, the DRX parameter for the terminal of the master base station may be referred to as a first DRX parameter, and the DRX parameter for the terminal of the secondary base station may be referred to as a second DRX parameter.

The second embodiment includes the method disclosed in Fig. As shown in FIG. 11, the master base station determines a DRX parameter for the terminal (S1110), and proceeds to the RRC connection reconfiguration procedure for the DRX configuration for the terminal and the master base station (S1120). Then, based on the determined DRX parameters, at least one candidate DRX parameter set that can be set by the secondary base station is configured (S1130) and transmitted to the secondary base station (S1140). Here, each candidate DRX parameter set is a list of candidate DRX parameters, and may include at least one of a DRX start offset, a short DRX cycle, and a long DRX cycle.

Upon receiving the candidate DRX parameter set from the master base station, the secondary base station selects one of the at least one candidate DRX parameter sets (S1150) and transmits the selected candidate DRX parameter set to the master base station (S1160). At this time, the secondary base station may transmit an index of the selected candidate DRX parameter set to the master base station instead of the selected candidate DRX parameter set.

Thereafter, the master base station performs an RRC connection reconfiguration procedure for DRX configuration between the secondary base station and the terminal using the candidate DRX parameter set selected by the secondary base station (S1170). At this time, the master base station does not recognize or interpret the DRX parameter selected by the secondary base station, and may include the DRX parameter when constructing the RRC connection reconfiguration message.

In addition, the master base station can transmit the already determined DRX parameters to the secondary base station although it is not configured for the terminal. In this case, step S1120 is skipped, and DRX parameters for the terminal of the master base station and DRX parameters for the terminals of the secondary base station can both be transmitted to the terminal when the RRC connection reconfiguration procedure of step 1170 is in progress.

The third embodiment includes the method disclosed in Fig. As shown in FIG. 12, the master base station may first transmit DRX related information to the secondary base station (S1210). Here, the DRX-related information may be included in the capability information of the UE. In this case, the secondary base station itself configures DRX parameters for the terminal based on the DRX-related information (1220) and transmits the configured DRX parameters to the master base station (S1230).

The master base station checks the DRX parameter received from the secondary base station and determines whether the DRX parameter for the terminal of the master base station has been changed. In this case, the DRX parameter received from the secondary base station must be recognized and interpreted by the master base station, and the master base station may deny the application of the DRX parameter received from the secondary base station. In case of rejecting the application of the DRX parameter received from the secondary base station, the master base station may notify the secondary base station that the application of the DRX parameter is rejected (S1240). In this case, the secondary base station again modifies the DRX parameters to the master base station (S1260). If the master base station permits the DRX parameter received from the secondary base station, the master base station may include the DRX parameter as it is when constructing the RRC connection reconfiguration message (S1270).

13 is a flowchart illustrating an operation of a master base station according to an embodiment of the present invention.

If there is a terminal capable of dual connection with the secondary base station, the master base station constructs dual connection configuration information for the terminal and transmits it to the terminal (S1310). Then, the master base station configures a DRX parameter for the terminal (S1320), and transmits the DRX-related information to the secondary base station via the Xn interface (S1330). Here, the DRX-related information may include at least one of a DRX start offset, a short DRX cycle, and a long DRX cycle. In addition, the DRX-related information may include reference information for adjusting the DRX deactivation timer value of the secondary base station based on QoS. The DRX-related information may be transmitted to the secondary base station through an AS-Config message or a message defined in the Xn interface.

When the master base station receives the DRX parameter of the secondary base station determined based on the DRX-related information from the secondary base station (S1340), it does not recognize or interpret the received DRX parameter and directly performs RRC connection reconfiguration And configures the DRX through the RRC connection reconfiguration procedure using the RRCC connection reconfiguration message including the DRX parameter (S1350).

On the other hand, when the master base station transmits the candidate DRX parameter sets that can be set by the secondary base station determined based on the DRX parameter of the master base station as the DRX related information, the master base station selects the candidate DRX parameter sets selected by the secondary base station from the secondary base station Receive a candidate DRX parameter set, or receive an index of the selected candidate DRX parameter set. Even in this case, the master base station can directly include the DRX parameter selected by the secondary base station in the RRC connection reconfiguration message together with the DRX parameter of the master base station without recognizing or interpreting the DRX parameter.

On the other hand, when the master base station transmits the capability information of the terminal to the secondary base station, the master base station can receive the DRX parameter configured by the secondary base station based on the capability information of the terminal from the secondary base station. In this case, the master base station determines whether or not the DRX parameter received from the secondary base station is applied, and when the application rejects the received DRX parameter, informs the secondary base station. When the secondary base station receives the application rejection message for the DRX parameter from the master base station, it can retransmit the DRX parameters to the master base station again. If the master base station permits the application of the modified DRX parameters from the secondary base station, The modified DRX parameter may be transmitted to the UE through a reconfiguration procedure.

14 is a flowchart illustrating an operation of a secondary base station according to an embodiment of the present invention.

When the secondary connection configuration information is received from the master base station, the secondary base station configures a dual connection with the master base station and transmits a response to the connection to the master base station (S1410).

Subsequently, the secondary base station receives the DRX-related information from the master base station (S1420), configures the DRX parameters of the secondary base station for the terminal having the dual connection to the master base station and the secondary base station based on the received DRX-related information (S1430) , And transmits the configured DRX parameters to the master base station (S1440). Here, the DRX-related information may be transmitted from the master base station to the secondary base station through an AS-Config message or a message defined in the Xn interface, and may include at least one of a DRX start offset, a short DRX cycle, Parameter. In addition, the DRX-related information may include reference information for adjusting the DRX deactivation timer value of the secondary base station based on QoS.

On the other hand, the secondary base station can receive the candidate DRX parameter set configurable by the secondary base station from the master base station. In this case, the secondary base station may select one of the candidate DRX parameter sets, and then transmit the selected DRX parameter set or the index of the selected DRX parameter set to the master base station.

Further, the secondary base station can receive the capability information of the terminal from the master base station in the DRX parameter configuration. In this case, the secondary base station can transmit the DRX parameter configured based on the capability information of the terminal to the master base station. The DRX parameter configured based on the capability information of the UE may be rejected according to the determination of the master base station. In this case, the secondary base station can reconstruct the DRX parameter and transmit it to the master base station.

15 is a flowchart illustrating an operation of a terminal according to an embodiment of the present invention.

If the terminal receives the dual connection configuration information for the dual connection with the secondary base station from the master base station, the terminal establishes a dual connection between the master base station and the secondary base station based on the dual connection configuration information (S1510). If the DRX parameter is received from the master base station through the RRC connection reconfiguration stop (S1520), the application range of the DRX parameter is checked (S1530) and the DRX operation is started with respect to the serving cells within the coverage range (S1540).

16 is a block diagram illustrating a master base station, a secondary base station, and a terminal according to an embodiment of the present invention.

First, referring to the master base station 1610, the master base station 1610 includes a configuration unit 1611, a transmission unit 1612, and a reception unit 1613.

The configuration unit 1611 configures the dual connection configuration information for the corresponding terminal 1630 when the terminal 1630 capable of dual connection with the secondary base station 1620 exists and the terminal 1630 configures the DRX The DRX parameter for the terminal 1630 is configured.

The transmitting unit 1612 transmits the DRX related information including the DRX parameter configured in the configuration unit 1611 to the secondary base station 1620 and transmits the dual connection configuration information configured in the configuration unit 1611 to the terminal 1630. Here, the DRX-related information may include reference information for adjusting the DRX deactivation timer value of the secondary base station based on QoS. The transmitting unit 1612 transmits the DRX parameter received from the secondary base station 1620 to the terminal 1630. [ At this time, the master base station 1610 does not recognize or interpret the DRX parameters received from the secondary base station 1620. Therefore, the transmitter 1612 includes the DRX parameters received from the secondary base station 1620 in the RRC connection reconfiguration message, and transmits the DRX parameters to the terminal 1630. The transmission unit 1612 can use the AS configuration message or the message defined in the Xn interface when transmitting the DRX related information to the secondary base station 1620 and transmit the dual connection configuration information or the DRX parameter to the terminal 1630 The RRC connection reconfiguration message is available. Here, the DRX parameter may be a parameter of at least one of a DRX start offset, a short DRX cycle, and a long DRX cycle.

The receiving unit 1613 receives the DRX parameter from the secondary base station 1620 and transmits the received DRX parameter to the transmitting unit 1612. [

On the other hand, the configuration unit 1611 can configure at least one candidate DRX parameter set configurable in the secondary base station 1620 based on the DRX parameters configured for the UE. In this case, the transmitting unit 1612 transmits the candidate DRX parameter set to the secondary base station 1620, the receiving unit 1613 receives the candidate DRX parameter set selected from the candidate DRX parameter sets from the secondary base station 1620, And receives an index of the selected candidate DRX parameter set. Also in this case, the transmitter 1612 directly transmits the DRX parameter included in the RRC connection reconfiguration message to the terminal 1630 without recognizing or interpreting the DRX parameter received from the secondary base station 1620.

The secondary base station 1620 includes a receiving unit 1621, a configuration unit 1622, and a transmission unit 1623.

The receiving unit 1621 receives the dual connection configuration information, the DRX related information, and the like from the master base station 1610. Here, the DRX-related information may include at least one of a DRX start offset, a short DRX cycle, and a long DRX cycle, or may be included in capability information of the terminal 1630. [ The DRX-related information may include reference information for adjusting a DRX deactivation timer value of the secondary base station based on QoS.

The configuration unit 1622 configures a dual connection with the master base station 1610 when the dual connection configuration information is received, and when the DRX-related information is received, configures the DRX parameter for the terminal 1630 based on the received DRX- do.

The transmitting unit 1623 transmits the DRX related information configured in the configuration unit 1622 to the master base station 1610. Here, when the configuration unit 1622 configures a DRX parameter based on the capability information of the terminal 1630 received from the master base station 1610 and the transmission unit 1623 transmits the DRX parameter to the master base station 1610, The parameter may be rejected at the discretion of the master base station 1610. In this case, the configuration unit 1622 reconstructs the DRX parameters, and the transmission unit 1623 can retransmit the reconstructed DRX parameters.

Meanwhile, the receiving unit 1621 can receive the candidate DRX parameter set configurable in the secondary base station 1620 from the master base station 1621. [ In this case, the configuration unit 1622 selects one of the candidate DRX parameter sets, and the transmission unit 1623 can transmit the selected candidate DRX parameter set or the index of the selected candidate DRX parameter set to the master base station.

The terminal 1630 includes a receiving unit 1631 and an identifying unit 1632.

The receiving unit 1631 receives the configuration information for the dual connection with the secondary base station 1620 from the master base station 1610 and receives the DRX parameter through the RRC connection reconfiguration message in the DRX configuration.

If the DRX parameter is included in the RRC connection reconfiguration message, the confirmation unit 1632 can check the coverage of the DRX parameter and start the DRX operation for the serving cells within the coverage of the DRX parameter.

In the above-described exemplary system, the methods are described on the basis of a flowchart as a series of steps or blocks, but the present invention is not limited to the order of the steps, and some steps may occur in different orders or simultaneously . It will also be understood by those skilled in the art that the steps shown in the flowchart are not exclusive and that other steps may be included or that one or more steps in the flowchart may be deleted without affecting the scope of the invention.

The above-described embodiments include examples of various aspects. While it is not possible to describe every possible combination for expressing various aspects, one of ordinary skill in the art will recognize that other combinations are possible. Accordingly, it is intended that the invention include all alternatives, modifications and variations that fall within the scope of the following claims.

Claims (10)

A method for configuring a discontinuous reception (DRX) parameter by a master base station in a wireless communication system,
Determining a first DRX parameter for a terminal dual-connected to the master base station and the secondary base station;
Transmitting information related to the first DRX parameter to the secondary base station;
Receiving from the secondary base station a second DRX parameter determined based on information related to the first DRX parameter; And
And transmitting the received second DRX parameter to the terminal
Gt; DRX < / RTI > The method according to claim 1,
Wherein the information related to the first DRX parameter comprises:
(AS-Config) message or a message defined in the Xn interface to the secondary base station. The method according to claim 1,
Wherein the information related to the first DRX parameter comprises:
A DRX start offset, a short DRX cycle, and a long DRX cycle. The method according to claim 1,
Wherein the information related to the first DRX parameter comprises:
And reference information for adjusting a DRX deactivation timer value of the secondary base station based on Quality of Service (QoS). The method according to claim 1,
Wherein the information related to the first DRX parameter comprises:
Wherein the DRX parameter is included in capability information of the UE. 6. The method of claim 5,
After receiving the second DRX parameter,
Further comprising determining whether to apply the second DRX parameter. The method according to claim 6,
After determining whether to apply the second DRX parameter,
And receiving the reconfigured second DRX parameter based on the DRX-related information when the application of the second DRX parameter is rejected. The method according to claim 1,
Wherein the information related to the first DRX parameter comprises:
And at least one candidate DRX parameter set that can be set by the secondary base station. 9. The method of claim 8,
Wherein the second DRX parameter comprises:
Wherein the candidate DRX parameter is a candidate DRX parameter selected from the at least one candidate DRX parameter set. A method of configuring a DRX (Discontinuous Reception) parameter in a secondary base station in a wireless communication system,
Receiving from the master base station at least one candidate DRX parameter set configured for a master base station and a terminal dual-connected through the secondary base station;
Selecting a candidate DRX parameter set to configure for the terminal among the at least one candidate DRX parameter set; And
Transmitting the selected candidate DRX parameter set or the index of the selected candidate DRX parameter set to the master base station
Gt; DRX < / RTI >

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