WO2015065076A1 - Method and apparatus for configuring parameter for discontinuous reception in wireless communication system using dual connectivity scheme - Google Patents

Abstract

Suggested are a method and an apparatus for configuring parameters for discontinuous reception in a wireless communication system using a dual connectivity scheme. A method for configuring, by a master base station, discontinuous reception (DRX) parameters may comprise the steps of: determining a first DRX parameter for a terminal dual-connected to the master base station and a secondary base station; transmitting information related to the first DRX parameter to the secondary base station; receiving a second DRX parameter determined on the basis of the information related to the first DRX parameter from the secondary base station; and transmitting the received second DRX parameter to the terminal.

Description

Method and apparatus for parameter configuration for discontinuous reception in wireless communication system using dual connection method

The present invention relates to a method and apparatus for configuring a Discontinuous Reception (DRX) parameter for discontinuous reception when a terminal has dual connectivity with at least two base stations in a wireless communication system.

In a wireless communication system, a terminal may perform wireless communication through two or more base stations of at least one base station constituting at least one serving cell. This is called dual connectivity. In other words, dual connectivity is an operation in which a terminal configured to at least two or more different network points and an RRC connection state consumes radio resources provided by the network points. can do. Here, at least two different network points may be a plurality of base stations physically or logically separated, one of which is a master base station (MeNB), and the other base stations are secondary base station (SenB) base stations. Can be.

In dual connectivity, each base station transmits downlink data and receives uplink data through a bearer configured for one terminal. In this case, one bearer may be configured through one base station or two or more different base stations. In addition, at least one serving cell may be configured in each base station in dual connectivity, and each serving cell may be operated in an activated or deactivated state. At this time, the master base station is configured with a primary (serving cell) (PCell: Primary Cell) configurable in the conventional carrier aggregation (CA) method, the secondary base station (SCell: Secondary (serving) Cell) ) Can only be configured. Here, carrier aggregation is a technique for efficiently using fragmented small bands, and a single base station combines a plurality of physically continuous or non-continuous bands in a frequency domain to logically large bands. It is intended to produce the same effect as using a band.

On the other hand, the power consumption by the receiving circuit of the general terminal is a level that can not be ignored, the continuous operation of the receiving circuit increases the power consumption of the terminal. Accordingly, the wireless communication system supports discontinuous reception (DRX) to reduce power consumption of the terminal. DRX refers to a function that allows the terminal to stop monitoring the Packet Data Control CHannel (PDCCH) for a predetermined period (ie, a sleep period or an inactive time), and the terminal is active with a certain periodicity in the DRX mode. Repeat time and inactivity time. Here, the activation time means the time for monitoring the PDCCH, and the inactivity time means the time for stopping the monitoring of the PDCCH.

When discontinuous reception (DRX) is configured in a terminal in dual connectivity, the terminal performs a separate DRX operation for each base station, and the parameters for the DRX operation are also configured separately for each base station. Therefore, even if DRX is configured in the UE in dual connectivity, if the inactivity time for the master base station and the inactivity time for the secondary base station do not overlap each other, the UE always monitors the PDCCH for the master base station or the secondary base station even in the DRX mode. There is a problem that this does not decrease.

Therefore, there is a need for a method for synchronizing an inactivity time (or active time) for a master base station and an inactivity time (or active time) for a secondary base station when configuring DRX in a terminal in dual connectivity.

An object of the present invention is to provide a parameter configuration method and apparatus for discontinuous reception in a wireless communication system using a dual connection method.

Another technical problem of the present invention is to provide a method and apparatus for configuring a DRX parameter that can reduce the overall active time of the terminal when configuring a DRX in a dual connectivity terminal.

Another technical problem of the present invention is to provide a method and apparatus for configuring a DRX parameter capable of synchronizing an active time for a secondary base station and an active time for a master base station of the terminal when configuring a DRX in a dual connectivity terminal.

According to an aspect of the present invention, a method for configuring a Discontinuous Reception (DRX) parameter by a master base station includes: determining a first DRX parameter for a terminal dually connected with the master base station and the secondary base station; Transmitting information to the secondary base station, receiving a second DRX parameter determined based on the information related to the first DRX parameter from the secondary base station, and transmitting the received second DRX parameter to the terminal. It may include.

According to another aspect of the present invention, a method in which a secondary base station configures a DRX parameter comprises: receiving from the master base station at least one candidate DRX parameter set configured for a master base station and a terminal duplexed through the secondary base station; Selecting a candidate DRX parameter set to be configured for the UE from one candidate DRX parameter set, and transmitting the selected candidate DRX parameter set or an index of the selected candidate DRX parameter set to the master base station. .

In the wireless communication system, since the active time for the master base station and the active time for the secondary base station can be synchronized when the DRX is configured to the terminal having dual connectivity, the battery consumption of the terminal may be reduced as the total active time of the terminal is reduced. .

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

2 is a diagram illustrating a structure of a bearer service in a wireless communication system.

3 is a diagram illustrating a dual connection situation of a terminal according to the present invention.

4 is a view showing a user plane structure for a dual connection according to the present invention.

5 and 6 are diagrams illustrating a protocol structure of base stations in downlink transmission of user plane data.

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

8 to 10 are signal flow diagrams illustrating a method for configuring DRX parameters through cooperation between a master base station and a secondary base station according to an embodiment of the present invention.

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

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

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

14 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 present disclosure will be described in detail with reference to the accompanying drawings and examples, together with the contents of the present disclosure. In adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are used as much as possible even though they are shown in different drawings. In addition, in describing the embodiments of the present specification, when it is determined that a detailed description of a related well-known configuration or function may obscure the gist of the present specification, the detailed description thereof will be omitted.

In addition, the present specification describes a wireless communication network, the operation performed in the wireless communication network is performed in the process of controlling the network and transmitting data in the system (for example, the base station) that is in charge of the wireless communication network, or the corresponding wireless Work may be done at the terminal coupled to the network.

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

1 illustrates 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 Long Term Evolution (LTE) or LTE-A (Advanced) system. Wireless communication systems include Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier-FDMA (SC-FDMA), and OFDM-FDMA Various multiple access schemes such as OFDM, TDMA, and OFDM-CDMA may be used.

Referring to FIG. 1, an Evolved-UMTS Terrestrial Radio Access Network (E-UTRAN) is a base station providing a control plane (CP) and a user plane (UP) to a user equipment (UE) 10. (eNB: evolved NodeB, 20).

The terminal 10 may be fixed or mobile, and may be called by other terms such as mobile station (MS), advanced MS (AMS), user terminal (UT), subscriber station (SS), and wireless device (Wireless Device). have.

The base station 20 generally refers to a station for communicating with the terminal 10, and includes a base station (BS), a base transceiver system (BTS), an access point, an femto base station, and a pico-eNB. It may be called other terms such as a base station (pico-eNB), a home base station (Home eNB), a relay, and the like. The base stations 20 are physically connected to each other through an optical cable or a digital subscriber line (DSL), and may exchange signals or messages with each other through an Xn interface. 1 illustrates an example in which base stations 20 are connected through an X2 interface.

Hereinafter, the description of the physical connection will be omitted and the logical connection will be 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 the Mobility Management Entity (MME) through the S1-MME interface, and is connected to the Serving Gateway (S-GW) through the S1-U interface. The base station 20 exchanges contents information of the terminal 10 and information for supporting mobility of the terminal 10 through the MME and the S1-MME interface. In addition, the S-GW and the data to be serviced to each terminal 10 through the S1-U interface.

Although not shown in FIG. 1, the EPC 30 includes MME, S-GW, and Packet Data Network Gateway (P-GW). The MME has access information of the terminal 10 or information on the capability of the terminal 10, and this information is mainly used for mobility management of the terminal 10. The S-GW is a gateway having an E-UTRAN as an endpoint, and the P-GW is a gateway having a PDN (Packet Data Network) as an endpoint.

The E-UTRAN and the EPC 30 may be integrated to be referred to as EPS (Evolved Packet System), and the traffic flows from the radio link to which the terminal 10 connects to the base station 20 to the PDN connected to the service entity are all IP. It works based on (Internet Protocol).

On the other hand, the air interface between the terminal 10 and the base station 20 is referred to as a "Uu interface". Layers of the radio interface protocol between the terminal 10 and the network may include a first layer L1 defined in a 3GPP (3rd Generation Partnership Project) -based wireless communication system (UMTS, LTE, LTE-Advanced, etc.), It may be divided into a second layer L2 and a third layer L3. Among these, 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 in the third layer exchanges an RRC message for the UE. Control radio resources between the network and the 10.

In order for a terminal to transmit user data (eg, an IP packet) to an external internet network or to receive user data from an external internet network, the terminal exists between mobile communication network entities existing between the terminal and the external internet network. Resources must be allocated to different paths. As such, a path in which resources are allocated between mobile communication network entities to enable data transmission and reception is called a bearer.

2 is a diagram illustrating a structure of a bearer service in a wireless communication system.

2 illustrates a path in which end-to-end service is provided between a terminal and an internet network. Here, the end-to-end service means a service that requires a path between the UE and the P-GW (EPS Bearer) and the P-GW and the external bearer for the internet network and data service. . Here, the external path is a bearer between the P-GW and the Internet network.

When the terminal transmits data to the external internet network, the terminal first transmits the data to the base station 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 delivers the data received from the base station to the P-GW via the S5 / S8 bearer, and finally the data is delivered through the external bearer to a destination existing in the P-GW and the external Internet network.

Similarly, in order to transmit data from the external Internet network to the terminal, the data can be delivered to the terminal through each bearer in the reverse direction as described above.

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

The bearers provided by the wireless communication system are collectively called an Evolved Packet System (EPS) bearer. An EPS bearer is a delivery path established between a UE and a P-GW for transmitting IP traffic with a specific QoS. The P-GW may receive IP flows from the Internet or send IP flows to the Internet. Each EPS bearer is set with QoS decision parameters that indicate the nature of the delivery path. One or more EPS bearers may be configured per UE, and one EPS bearer uniquely represents a concatenation of one E-UTRAN Radio Access Bearer (E-RAB) and one S5 / S8 bearer.

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

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

The S5 / S8 bearer is a bearer of the S5 / S8 interface. Both S5 and S8 are bearers present at the interface between the S-GW and the P-GW. The S5 interface exists when the S-GW and the P-GW belong to the same operator, and the S8 interface belongs to the provider (Visited PLMN) roamed by the S-GW, and the P-GW has subscribed to the original service (Home). PLMN).

The E-RAB uniquely represents the concatenation of the S1 bearer and the corresponding RB. When there is one E-RAB, one-to-one mapping is established between the 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 a bearer at the interface between the base station and the S-GW.

RB means two types of data radio bearer (DRB) and signaling radio bearer (SRB). However, in the present invention, RB is a DRB provided in the Uu interface to support a service of a user. . Therefore, the RB expressed without distinction is distinguished from the SRB. The RB is a path through which data of the user plane is transmitted, and the SRB is a path through which data of the control plane, such as the RRC layer and NAS control messages, are delivered. One-to-one mapping is established between RB, E-RAB and EPS bearer. The base station maps and stores the DRB and the S1 bearer one-to-one to generate a DRB that binds both uplink and downlink. The S-GW maps the S1 bearer and the S5 / S8 bearer one-to-one and stores them in order to generate an S1 bearer and an S5 / S8 bearer that bind both uplink and downlink.

EPS bearer types include a default bearer and a dedicated bearer. When the terminal accesses the wireless communication network, the terminal is assigned an IP address and creates a PDN connection. At this time, a default EPS bearer is generated. That is, a default bearer is first created when a new PDN connection is created. When a user uses a service (for example, the Internet, etc.) through a default bearer, and uses a service (for example, VoD, etc.) that the default bearer cannot provide QoS properly, the user may be on-demand. A dedicated bearer is created. In this case, the dedicated bearer may be set to a different QoS from the bearer that is already set. QoS decision parameters applied to the dedicated bearer are provided by a Policy and Charging Rule Function (PCRF). Upon creation of a dedicated bearer, the PCRF may receive subscription information of a user from a Subscriber Profile Repository (SPR) to determine QoS determination parameters. For example, up to 15 dedicated bearers may be created, and four of the 15 dedicated bearers are not used in the LTE system. Therefore, up to 11 dedicated bearers may be generated in the LTE system.

The EPS bearer includes a QoS Class Identifier (QCI) and Allocation and Retention Priority (ARP) as basic QoS determination parameters. EPS bearers are classified into GBR (Guaranteed Bit Rate) bearers and non-GBR bearers according to QCI resource types. The default bearer is always set to a non-GBR type bearer, and the dedicated bearer may be set to a GBR type or non-GBR type bearer. The GBR bearer has GBR and MBR (Maximum Bit Rate) as QoS decision parameters in addition to QCI and ARP. After the QoS that the wireless communication system must provide as a whole is defined as an EPS bearer, each QoS is determined for each interface. Each interface sets up a bearer according to the QoS it needs to provide.

3 is a diagram illustrating an example of a dual connection situation of a terminal according to the present invention.

In FIG. 3, for example, the terminal 550 enters an area where 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 overlap. The case is shown.

In this case, in order to support additional data service through the small cell (F1) in the secondary base station 510 while maintaining the existing wireless connection and data service connection through the macro cell (F2) in the master base station 500, Configure a dual connection for the terminal 550. Accordingly, user data arriving at the master base station 500 may be delivered 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 may receive the service through the F2 frequency band from the master base station 500, and may receive the service through the F1 frequency band from the secondary base station 510. In the above example, the master base station 500 uses the F2 frequency band and the secondary base station 510 is described as using the F1 frequency band. However, the present invention is not limited thereto, and the master base station 500 and the secondary base station ( 510 may all use the same F1 or F2 frequency band.

4 is a view showing the structure of the user plane for a dual connection according to the present invention.

Referring to FIG. 4, dual connectivity includes an arbitrary terminal, one master base station (MeNB), and at least one secondary base station (SeNB). Dual connectivity may be divided into three options as shown in FIG. 4 according to a method of dividing user plane data. 4 illustrates, for example, the concept of the three options for downlink transmission of user plane data.

The first option is when the S1-U interface has endpoints in the secondary base station as well as in the master base station. In this case, each base station (MeNB and SeNB) transmits downlink data through an EPS bearer (EPS bearer # 1 in the case of the master base station, EPS bearer # 2 in the case of the secondary base station) configured for one terminal. Since user plane data is splitting in the core network (CN), it is also called a CN split.

Second option: The S1-U interface has endpoints only at the master base station, but bearers do not differentiate and only one bearer is mapped to each base station.

Third option: where the S1-U interface has an endpoint only at the master base station and Barrer differentiates into multiple base stations. In this case, because the bearer differentiates, it is also called a bearer split. In a bearer split, since one bearer is divided into a plurality of base stations, data is transmitted in two flows (or more flows). Calling bearer splits as multi-flow, multi-node (eNB) transmission, inter-eNB carrier aggregation, etc. in that information is transmitted through multiple flows Also

On the other hand, when the endpoint of the S1-U interface is the master base station (ie, the second or third option) in terms of the protocol structure, the protocol layer in the secondary base station must support the segmentation or re-segmentation process. This is because the physical interface and the segmentation process are closely related to each other, and when using non-ideal backhaul, the segmentation or reclassification process should be the same as the node transmitting the RLC PDU. Therefore, considering the protocol structures for dual connectivity in the RLC layer or more as follows.

1. This is a case where the PDCP layer exists independently at each base station. This is also called the independent PDCP type. In this case, each base station may use the operation of the existing LTE layer 2 protocol in the bearer as it is. This may apply to all of the first to third options.

2. The RLC layer is independently present in each base station. This is also called an independent RLC type. In this case, the S1-U interface is the endpoint of the master base station, and the PDCP layer exists only in the master base station. In the case of a bearer split (third option), the RLC layer is separated on both the network and the terminal side, and there is an independent RLC bearer for each RLC layer.

3. The RLC layer is divided into a 'master RLC' layer of a master base station and a 'slave RLC' layer of a secondary base station. This is also called master-slave RLC type. In this case, the S1-U interface is the end point of the master base station, a part of the PDCP layer and the RLC layer (master RLC layer) is present in the master base station, a part of the RLC layer (slave RLC layer) is present in the secondary base station. There is only one RLC layer paired with the master RLC layer and the slave RLC layer in the terminal.

Accordingly, the dual connection may be configured as shown in FIG. 5 or 6 by the combination of the above options and types.

5 and 6 are diagrams illustrating a protocol structure of base stations in downlink transmission of user plane data according to the present invention.

First, referring to FIG. 5, a physical layer (PHY) layer of a terminal and a base station provides an information transfer service to an upper layer by using a physical channel. The physical layer is connected to the upper layer by a medium access control (MAC) layer through a transport channel. Data is transmitted through a transport channel between the MAC layer and the physical layer. Transport channels are classified according to how data is transmitted over the air interface. In addition, data is transmitted through a physical channel between different physical layers (that is, between a physical layer of a terminal and a base station). The physical channel may be modulated by an orthogonal frequency division multiplexing (OFDM) scheme and utilizes space generated by time, frequency, and a plurality of antennas as radio resources.

For example, a physical downlink control channel (PDCCH) of a physical channel informs a terminal of resource allocation of a PCH (Paging CHannel) and DL-SCH (DownLink Shared CHannel) and HARQ (Hybrid Automatic Repeat Request) information related to the DL-SCH, The terminal may carry an uplink scheduling grant informing of resource allocation of uplink transmission. In addition, the Physical Control Format Indicator CHannel (PCFICH) informs the UE of the number of OFDM symbols used for the PDCCHs and is transmitted every subframe. In addition, the PHICH (Physical Hybrid ARQ Indicator CHannel) carries a HARQ ACK / NAK signal in response to the uplink transmission. In addition, the physical uplink control channel (PUCCH) carries uplink control information such as HARQ ACK / NAK, scheduling request, and CQI for downlink transmission. In addition, the PUSCH (Physical Uplink Shared CHannel) carries an UL-SCH (UpLink Shared CHannel). If necessary according to the configuration and request of the base station, the PUSCH may include channel state information (CSI) information such as HARQ ACK / NACK and CQI.

The MAC layer may perform multiplexing or demultiplexing into a transport block provided as a physical channel on a transport channel of a MAC service data unit (SDU) belonging to the logical channel and mapping between the logical channel and the transport channel. The MAC layer provides a service to a Radio Link Control (RLC) layer through a logical channel. The logical channel may be divided into a control channel for transmitting control region information and a traffic channel for delivering user region information. As an example, services provided from the MAC layer to a higher layer include data transfer or radio resource allocation.

Functions of the RLC layer include concatenation, segmentation, and reassembly of RLC SDUs. The RLC layer uses a transparent mode (TM), an unacknowledged mode (UM), and an acknowledgment mode (AM) in order to guarantee various quality of services (QoS) required by a radio bearer (RB). Three modes of operation are provided: Acknowledgment Mode.

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

The RRC layer is responsible for the control of 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 the terminal and the 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 operation method. The RB may be classified into a signaling RB (SRB) and a data RB (DRB). The SRB is used as a path for transmitting RRC messages and non-access stratum (NAS) messages in the control plane, and the DRB is used as a path for transmitting user data in the user plane.

The non-access stratum (NAS) layer located above the RRC layer performs functions such as session management and mobility management. If 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 it is in an RRC idle state. do.

The S1-U interface has endpoints in the secondary base station as well as in the master base station, and the case where the PDCP layer is independently present in each base station (independent PDCP type) is shown. In this case, each of the master base station and the secondary base station has a PDCP layer, RLC layer and MAC layer, 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 the packet transmitted by the secondary base station, and there is an advantage that there is little or no impact on RDCP / RLC and GTP-U / UDP / IP. In addition, since there is less demand between the 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, the master base station does not need to route all traffic, and the secondary base station for the dual-connected terminal The advantage is that it can support local break-out and content caching.

Meanwhile, referring to FIG. 6, it is illustrated that the S1-U interface has an endpoint only at the master base station, is a bearer split, and the RLC layer is independently present at each base station (independent RLC type). In this case, a PDCP layer, an RLC layer, and a MAC layer exist in the master base station, and only an RLC layer and a MAC layer exist in the secondary base station. The PDCP layer, the RLC layer, and the MAC layer of the master base station are each separated into a bearer level, one of which is connected to one of the RLC layers of the master base station, and connected to the RLC layer of the secondary base station through the Xn interface.

In this case, there is an advantage that the mobility of the secondary base station is hidden in the core network, there is no security effect requiring encryption at the master base station, and data forwarding between the secondary base stations is not unnecessary when the secondary base station is changed. In addition, the master base station can pass RLC processing to the secondary base station, there is little or no effect on the RLC, and if possible, can utilize the radio resources through the master base station and the secondary base station for the same bearer, while moving the secondary base station Since the master base station can be used, there is an advantage that the requirements for mobility of the secondary base station are small.

On the other hand, Carrier Aggregation (CA) is a technology for efficiently using fragmented small bands, in which one base station has a plurality of physically continuous or non-continuous bands in the frequency domain. It is intended to combine the same effect as using a band with a logically large band. When the terminal configures the 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 specific serving cell provides non-access stratum (NAS) mobility information (eg, Tracking Area ID). Hereinafter, the specific serving cell is referred to as a primary serving cell (PCell) and serving cells other than the specific serving cell are referred to as secondary cells (SCell).

The main serving cell may be configured by a DL Downlink Primary Component Carrier (DL PCC) and an UL Uplink Primary Component Carrier (UL PCC). Meanwhile, the secondary serving cells may be configured in the form of a serving cell set together with the main serving cell according to the hardware capability of the terminal. The secondary serving cell may be configured only with DL Downlink Secondary Component Carrier (DL SCC) or may be configured with a pair of UL Uplink Secondary Component Carrier (SCC).

In this way, the serving cell set includes one main serving cell and at least one secondary serving cell. The primary serving cell can be changed only through the handover procedure and used for PUCCH transmission. The primary serving cell may not transition to the inactive state, but the secondary serving cell may transition to the inactive state.

The RRC connection resetting procedure is triggered when experiencing a radio link failure (RLF) in the main serving cell. However, the RLF of the secondary serving cell is not triggered.

Meanwhile, adding, removing, or reconfiguring a secondary serving cell to a serving cell set is performed through an RRC connection reconfiguration procedure, which is dedicated signaling. Therefore, when a new secondary serving cell is added to the serving cell set, the RRC connection reconfiguration message is also transmitted with system information on the new secondary serving cell. Therefore, in the case of the secondary serving cell, the monitoring operation for the change of the system information is not necessary.

The RRC connection reconfiguration procedure is performed for the purpose of modifying the RRC connection. For example, the RRC connection reconfiguration procedure may include the establishment / modification / release of RB, the handover, the establishment / modification / release of measurement, the addition / modification / release of secondary serving cell, etc. It can be performed for the purpose. 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 in a state where the E-UTRAN is connected to the terminal by RRC. When AS security (Access Stratum security) is activated, the 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 established during RRC connection establishment other than 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 an RRC connection and includes radio resource configuration information including measurement configuration information, mobility control information, and dedicated NAS information and security configuration. Can carry The radio resource configuration information may include information on RB, MAC main configuration, and physical channel configuration.

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

The wireless communication system supports discontinuous reception (DRX) to reduce power consumption of the terminal. DRX refers to a function that allows the UE to stop monitoring the PDCCH for a predetermined period (sleep period or inactive time), and as shown in FIG. 7, the UE is active and inactive in a constant cycle in the DRX mode. Repeat the time. Here, the activation time means the time for monitoring the PDCCH, and the inactivity time means the time for stopping the monitoring of the PDCCH.

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

If the terminal has a DRX parameter configured in the RRC connected state, the terminal 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 on the PDCCH. Here, discontinuous monitoring may mean that the UE monitors the PDCCH only in a specific subframe, and continuous monitoring may mean that the UE monitors the PDCCH in all subframes. On the other hand, if PDCCH monitoring is required in an operation independent of DRX such as a random access procedure, the UE may monitor the PDCCH according to the requirements of the operation.

The RRC layer manages several timers to control the DRX operation. Timers controlling the DRX operation include a duration timer (onDurationTimer), a DRX inactivity timer (DRxInactivity Timer), a DRX retransmission timer (drxRetransmission Timer). Other parameters to control DRX operation include long DRX cycle (longDRX-Cycle) and DRX start offset (drxStartOffset), and the base station optionally sets DRX short cycle timer (drxShortCycleTimer) and short DRX-cycle (shortDRX-Cycle). Can be. In addition, a HARQ Round Trip Time (RTT) timer is defined for each downlink HARQ process.

The DRX start offset is a value that defines the subframe where the DRX cycle begins. The DRX short cycle timer is a timer that defines the number of consecutive subframes that the UE should follow the short DRX cycle. The HARQ RTT timer is a timer that defines the minimum number of subframes before the interval in which downlink HARQ retransmission is expected by the UE.

The duration timer starts when the DRX cycle begins. In other words, the start of the duration timer coincides with the start of the DRX cycle. The duration timer expires when the value increases by '1' every PDCCH subframe and becomes equal to a preset expiration value. The duration timer is valid until the duration timer value is equal to the expiration value.

The DRX inactivity timer represents a time for monitoring the PDCCH for successful decoding of the PDCCH to be received later 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 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 for which downlink retransmission is expected by the terminal soon. The DRX retransmission timer is started when no retransmission data is received even though the HARQ RTT timer has expired. The UE may 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.

If 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 the PDCCH. The activation time may mean all sections in which the terminal is awake. For example, the terminal is activated when at least one of the above-described duration timer, DRX inactivity timer, and DRX retransmission timer is in progress. It is also activated when a scheduling request is sent or pending through the PUCCH, and is also activated when an uplink grant occurs for a pending HARQ transmission 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 not selected by the UE is successfully received.

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

Meanwhile, when DRX is configured, the UE stops the duration timer and the DRX inactivity timer when a DRX command MAC control element is received in each subframe. In addition, when the DRX Inactivity Timer expires or a DRX Command MAC control element is received, use the short DRX cycle and start or restart the DRX short cycle timer, or use the long DRX cycle. The UE uses a long DRX cycle when the DRX short cycle timer expires. If the short term DRX cycle or the long term DRX cycle is used, the terminal starts the duration timer.

On the other hand, when the terminal performs a handover (handover) from the source base station to the target base station, the message shown in Table 1 below to transmit the RRC information of the E-UTRA used in the handover preparation step from the source base station to the target base station Is used. The following message may be referred to as handover preparation information.

Table 1

-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, the radio resource configuration information required for handover in the E-UTRA is transmitted through the AS-Config field, and the local E-UTRAN context required 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 at the target base station so that the RRC configuration of the target base station can be changed during the handover preparation step. The information about the RRC configuration may be used after the handover is performed or when the RRC connection is reset. Table 2 below shows AS-Config information elements.

TABLE 2

-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

In Table 2, the antennaInfoCommon field provides information about the number of antenna ports of the source base station. The sourceDL-CarrierFreq field provides a 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 a 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 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 on algorithm configuration such as AS integrity protection and AC operation 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.

On the other hand, 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.

TABLE 3

-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 includes information used to handle IDC problems, and the reestablishmentInfo field includes information required for resetting an RRC connection. The HO field is a field that is essentially present in the handover in the E-UTRA, and the HO2 field is a field that is selectively present in the handover in the E-UTRA.

Meanwhile, a RadioResourceConfigDedicated information element is used to set up / modify / release RBs, modify MAC main settings, modify SPS configurations, and modify dedicated physical configurations. Table 4 below shows information elements dedicated to radio resource configuration.

Table 4

-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 may be explicitly signaled or set to a 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.

Table 5

-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 indicating a value of a duration timer, a drx-InactivityTimer field indicating a value of a DRX inactivity timer, and a drx-RetransmissionTimer field indicating a value of a DRX retransmission timer. In addition, the DRX configuration information includes a longDRX-CycleStartOffset field indicating a length of a long DRX cycle and a starting subframe, and a shortDRX field regarding a short DRX that may be configured as optional. The shortDRX field includes a shortDRX-Cycle subfield indicating the length of a short DRX cycle and a drxShortCycleTimer subfield indicating a value of a short term DRX cycle timer in which the UE is continuous.

The onDurationTimer field may be set to any one of {psf1, psf2, psf3, ..., psf200}. psf means a PDCCH subframe, and the number after psf indicates 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 up to one PDCCH subframe cumulatively including the subframe where the DRX cycle is started. If the onDurationTimer field = psf4, the duration timer expires after progressing up to four PDCCH subframes cumulatively from the start of the DRX cycle.

The drx-InactivityTimer field may be set to any one of {psf1, psf2, psf3, ..., psf2560}. For example, if the drx-InactivityTimer field = psf3, the DRX Inactivity Timer progresses up to three PDCCH subframes cumulatively including the subframe at the time when it is driven and then expires. The drx-RetransmissionTimer field may be set to any one 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 including the subframe at the time when it is driven.

The longDRX-CycleStartOffset field may be set to any one of values of {sf10, sf20, sf32, sf40, ..., sf2560} as the length of the long DRX cycle, and the subframe in which the long DRX cycle starts is defined in the long DRX cycle. It can be set to any one of {INTEGER (0..9), INTEGER (0..19), INTEGER (0..31), ..., INTEGER (0..2559)} corresponding to the length value. have. For example, if the longDRX-CycleStartOffset field = sf20, INTEGER (0..19), one long DRX cycle includes 20 subframes, and the long DRX cycle includes any subframe of subframe indexes 0 to 19. This long term DRX cycle start subframe may be selected.

The shortDRX-Cycle subfield constituting the shortDRX field may be set to any one of {sf2, sf5, sf8, ..., sf640}. For example, if the shortDRX-Cycle subfield = sf5, one short DRX cycle includes 5 subframes. In addition, the drxShortCycleTimer subfield constituting the shortDRX field may indicate any one of integers 1 to 16. For example, if the drxShortCycleTimer subfield = 3, the short DRX cycle has gone through three times and then expires.

When the terminal configures the DRX, the terminal proceeds with the DRX operation by using the aforementioned DRX parameters. However, when a terminal having dual connectivity through a master base station and a secondary base station configures DRX, the terminal performs a separate DRX operation for each base station, and the parameters for the DRX operation are also separately configured for each base station. do. Therefore, even if DRX is configured, the terminal configured with dual connectivity does not significantly reduce power consumption unless the inactivity time for the master base station and the inactivity time for the secondary base station do not overlap each other. Therefore, the present disclosure discloses a method in which a terminal configured with dual connectivity allows the active time for the master base station and the secondary base station to be synchronized as much as possible through cooperation between the master base station and the secondary base station during the DRX operation. According to this method, the total active 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 duration timer of the master base station and the start time of the second duration duration timer of the secondary base station. The start time of the duration timer of each base station may be synchronized by synchronizing the start time of a period of a short term DRX cycle or a long term DRX cycle. To this end, parameters such as a DRX start offset (drxStartOffset), a short DRX cycle (shortDRX-Cycle), and a long DRX cycle (longDRX-Cycle) may be used. If the DRX start offset value for each base station is set to the same offset value, the subframe in which the duration starts starts may be set identically or for a subset for each base station. In addition, if the short-term DRX cycle or long-term DRX cycle value for each base station is set in a multiple relationship, subframes in which the sustain period starts may be set equally or may be configured for each base station.

Another method of synchronizing the activation time for each base station of the terminal includes minimizing a DRX deactivation timer value. For example, for a service having a high delay tolerance based on QoS, minimizing the DRX inactivity timer value may minimize the active time. In general, a service through a secondary base station corresponds to a service having a higher delay tolerance than a service through a master base station. Therefore, when configuring the DRX alone, the secondary base station may configure the DRX inactivity timer value for the specific service to be smaller than the DRX inactivity timer value for the specific service when configuring the DRX with dual connectivity with the master base station. Can be. The criterion may be provided by the master base station to the secondary base station as DRX related information.

8 to 10 are signal flow diagrams illustrating a method for 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 in which the secondary base station configures the DRX parameter of the secondary base station for the terminal will be described based on the DRX related information provided by the master base station with reference to FIGS. 8 to 10.

The first embodiment includes the method disclosed in FIG. Referring to FIG. 8, the master base station determines a DRX parameter for the terminal (S1010) and performs an RRC connection reconfiguration procedure for configuring the DRX for the terminal and the master base station (S1020). In operation S1030, the DRX-related information is already transmitted to the secondary base station. Here, the DRX related information may be a DRX parameter as shown in FIG. 8, 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 through the Xn or X2 interface. (S1050).

The master base station performs an RRC connection reconfiguration procedure for the DRX configuration between the secondary base station and the terminal by using the DRX parameter received from the secondary base station (S1060). At this time, the master base station does not recognize or interpret the received DRX parameter, and may include the received DRX parameter as it is when configuring an RRC connection reconfiguration message.

Meanwhile, although the master base station is not configured for the terminal, it may transmit the determined DRX parameter to the secondary base station. In this case, step S1020 is omitted, and when the RRC connection reconfiguration procedure of step S1060 is performed, both the DRX parameter for the terminal of the master base station and the DRX parameter for the terminal of the secondary base station may be transmitted to the terminal. 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. 9, the master base station determines a DRX parameter for the terminal (S1110) and performs an RRC connection reconfiguration procedure for configuring the DRX for the terminal and the master base station (S1120). Then, at least one candidate DRX parameter set that can be set by the secondary base station is configured based on the determined DRX parameter (S1130), and is 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.

When the secondary base station receives the candidate DRX parameter set from the master base station, it 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 the 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 the DRX configuration between the secondary base station and the terminal by 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 as it is when configuring the RRC connection reconfiguration message.

In addition, although the master base station is not configured for the terminal, it may transmit the DRX parameters that have been determined to the secondary base station. In this case, step S1120 is omitted, and when the RRC connection reconfiguration procedure of step S1170 is performed, both the DRX parameter for the terminal of the master base station and the DRX parameter for the terminal of the secondary base station may be transmitted to the terminal.

The third embodiment includes the method disclosed in FIG. As shown in FIG. 10, 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 terminal and transmitted. In this case, the secondary base station automatically configures a DRX parameter for the terminal based on the DRX related information (1220), and transmits the configured DRX parameter to the master base station (S1230).

The master base station checks the DRX parameter received from the secondary base station to determine whether to change the DRX parameter for the terminal of the master base station. In this case, the DRX parameter received from the secondary base station should be recognized and interpreted by the master base station, at which time the master base station may refuse to apply the DRX parameter received from the secondary base station. When the application of the DRX parameter received from the secondary base station is rejected, the master base station may inform the secondary base station that the application of the DRX parameter is rejected (S1240), in which case the secondary base station modifies the DRX parameters again (S1250). It may transmit to the master base station (S1260). If the master base station accepts the DRX parameter received from the secondary base station, the master base station may include the DRX parameter as it is when configuring the RRC connection reconfiguration message (S1270).

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

If there is a terminal capable of dual connectivity with the secondary base station, the master base station configures the dual connectivity configuration information for the terminal and transmits it to the terminal (S1310). Thereafter, the master base station configures a DRX parameter for the terminal (S1320) and transmits the information related to the configured DRX to the secondary base station through the Xn interface (S1330). Here, the DRX related information may include at least one parameter of a DRX start offset, a short term DRX cycle, and a long term 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.

Then, 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), the RRC connection reconfiguration with the DRX parameter of the master base station as it is without recognizing or interpreting the received DRX parameter. The DRX may be configured through the RRC connection reconfiguration procedure using the RRC connection reconfiguration message including the DRX parameter in the message (S1350).

Meanwhile, when the master base station transmits candidate DRX parameter sets that can be set by the secondary base station determined based on the DRX parameters of the master base station as DRX related information, the master base station is selected by the secondary base station among the candidate DRX parameter sets from the secondary base station. A candidate DRX parameter set may be received or an index of the selected candidate DRX parameter set may be received. Even in this case, the master base station may be included in the RRC connection reconfiguration message together with the DRX parameters of the master base station without recognizing or interpreting the DRX parameter selected by the secondary base station.

Meanwhile, when the master base station transmits capability information of the terminal to the secondary base station, the master base station may receive a DRX parameter configured by the secondary base station itself based on the capability information of the terminal from the secondary base station. In this case, the master base station may determine whether to apply the DRX parameter received from the secondary base station, and notify the secondary base station if it rejects the application of the received DRX parameter. When the secondary base station receives the application rejection message for the DRX parameter from the master base station, the secondary base station can modify the DRX parameters and retransmit it to the master base station, and when the master base station allows the application of the modified DRX parameter from the secondary base station, the RRC connection The modified DRX parameter may be transmitted to the terminal through a reconfiguration procedure.

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

When the secondary base station receives the dual connectivity configuration information from the master base station, the secondary base station forms a dual connection with the master base station and transmits a response thereto to the master base station (S1410).

Then, when the secondary base station receives the DRX-related information from the master base station (S1420), based on the received DRX-related information, the secondary base station configures the DRX parameters of the secondary base station for the terminal having dual connectivity to the secondary base station (S1430). In operation S1440, the configured DRX parameter is transmitted to the master base station. 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, and a long DRX cycle. It may include a 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.

Meanwhile, the secondary base station may receive a candidate DRX parameter set configurable in 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.

In addition, the secondary base station may receive the capability information of the terminal from the master base station when configuring the DRX parameter. In this case, the secondary base station may transmit a 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 terminal may be rejected at the discretion of the master base station. In this case, the secondary base station may reconfigure the DRX parameter and transmit it to the master base station.

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

When the UE receives the duplex configuration information for the duplex connection with the secondary base station from the master base station, the duplex connection is established between the master base station and the secondary base station based on the duplex configuration information (S1510). After receiving the DRX parameter from the master base station through the RRC connection reconfiguration procedure (S1520), the application range of the DRX parameter is checked (S1530), and the DRX operation is started for the serving cells within the application range (S1540).

14 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 component 1611, a transmitter 1612, and a receiver 1613.

When the terminal 1630 capable of dual connectivity with the secondary base station 1620 is configured, the configuration unit 1611 configures dual connectivity configuration information for the corresponding terminal 1630, and the corresponding terminal 1630 configures DRX. In this case, a DRX parameter (hereinafter, referred to as a first DRX parameter) for the UE 1630 is configured.

The transmitter 1612 transmits the DRX related information including the first DRX parameter configured in the component 1611 to the secondary base station 1620 and transmits the dual connectivity configuration information configured in the component 1611 to the terminal 1630. do. Here, the DRX related information may include reference information for adjusting the DRX deactivation timer value of the secondary base station based on QoS. In addition, the transmitter 1612 transmits a DRX parameter (hereinafter, referred to as a second 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 second DRX parameter received from the secondary base station 1620. Accordingly, the transmitter 1612 includes the second DRX parameter received from the secondary base station 1620 in the RRC connection reconfiguration message as it is and transmits it to the terminal 1630. The transmitter 1612 may use an AS-Config message or a message defined in an Xn interface when transmitting DRX related information to the secondary base station 1620, and transmits dual connectivity configuration information or DRX parameters to the terminal 1630. RRC connection reconfiguration message may be used. Here, the DRX parameter may be at least one parameter of a DRX start offset, a short term DRX cycle, and a long term DRX cycle.

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

Meanwhile, the configuration unit 1611 may configure at least one candidate DRX parameter set configurable in the secondary base station 1620 based on the first DRX parameter configured for the terminal. In this case, the transmitter 1612 transmits the candidate DRX parameter set to the secondary base station 1620, and the receiver 1613 receives the candidate DRX parameter set selected from the candidate DRX parameter sets from the secondary base station 1620, Receive an index of the selected candidate DRX parameter set. Even in this case, the transmitter 1612 transmits the RRC connection reconfiguration message to the UE 1630 without any process of recognizing or interpreting the DRX parameter received from the secondary base station 1620.

Referring to the secondary base station 1620, the secondary base station 1620 includes a receiver 1621, a component 1622, and a transmitter 1623.

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

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

The transmitter 1623 transmits the DRX related information configured in the component 1622 to the master base station 1610. Here, when the configuration unit 1622 configures the DRX parameter based on the capability information of the terminal 1630 received from the master base station 1610, and the transmitter 1623 transmits it to the master base station 1610, the corresponding DRX The parameter may be rejected according to the determination of the master base station 1610. In this case, the configuration unit 1622 reconfigures the DRX parameters, and the transmitter 1623 may transmit the reconstructed DRX parameters.

Meanwhile, the receiver 1621 may receive a candidate DRX parameter set configurable in the secondary base station 1620 from the master base station 1610. In this case, the configuration unit 1622 selects one of the candidate DRX parameter sets, and the transmitter 1623 may 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 receiver 1631 and a confirmer 1632.

The receiver 1631 receives configuration information for dual connectivity with the secondary base station 1620 from the master base station 1610, and receives a DRX parameter through an RRC connection reconfiguration message when configuring the DRX.

When the DRX parameter is included in the RRC connection reconfiguration message, the identification unit 1632 may check the coverage of the DRX parameter to start a DRX operation on serving cells within the coverage of the DRX parameter.

In the exemplary system described above, the methods are described based on a flowchart as a series of steps or blocks, but the invention is not limited to the order of steps, and certain steps may occur in a different order or concurrently with other steps than those described above. Can be. In addition, those skilled in the art will appreciate that the steps shown in the flowcharts are not exclusive and that other steps may be included or one or more steps in the flowcharts may be deleted without affecting the scope of the present invention.

The above-described embodiments include examples of various aspects. Although not all possible combinations may be described to represent the various aspects, one of ordinary skill in the art will recognize that other combinations are possible. Accordingly, the invention is intended to embrace all other replacements, modifications and variations that fall within the scope of the following claims.

Claims (20)

1. A method for configuring a DRX (Discontinuous Reception) parameter by a master base station in a wireless communication system,

   Determining a first DRX parameter for a terminal dually connected with the master base station and the secondary base station;

   Transmitting information related to the first DRX parameter to the secondary base station;

   Receiving a second DRX parameter from the secondary base station determined based on the information related to the first DRX parameter; And

   Transmitting the received second DRX parameter to the terminal

   DRX parameter configuration method comprising a.
2. The method of claim 1,

   The information related to the first DRX parameter is

   DR-X parameter configuration method characterized in that it is transmitted to the secondary base station via an AS-Config message or a message defined in the Xn interface.
3. The method of claim 1,

   The information related to the first DRX parameter is

   And at least one parameter of a DRX start offset, a short term DRX cycle, and a long term DRX cycle.
4. The method of claim 1,

   The information related to the first DRX parameter is

   And DRC deactivation timer value of the secondary base station based on a quality of service (QoS).
5. The method of claim 1,

   The information related to the first DRX parameter is

   DRX parameter configuration method characterized in that the transmission is included in the capability information (capability information) of the terminal.
6. The method of claim 5,

   After receiving the second DRX parameter,

   And determining whether to apply the second DRX parameter.
7. The method of claim 6,

   After determining whether to apply the second DRX parameter,

   And receiving a reconfigured DRX parameter from the secondary base station when the application of the second DRX parameter is denied.
8. The method of claim 1,

   The information related to the first DRX parameter is

   And at least one candidate DRX parameter set configurable at the secondary base station.
9. The method of claim 8,

   The second DRX parameter is

   And a candidate DRX parameter set selected from the at least one candidate DRX parameter set or an index of the selected candidate parameter set.
10. In the method for the secondary base station configures the DRX (Discontinuous Reception) parameter in a wireless communication system,

    Receiving DRX related information determined for a terminal dually connected to the master base station and the secondary base station from a master base station;

    Determining a DRX parameter to be configured for the terminal based on the DRX related information; And

    Transmitting the determined DRX parameter to the master base station

    DRX parameter configuration method comprising a.
11. The method of claim 10,

    The DRX related information,

    DR-X parameter configuration method characterized in that it is received through an AS-Config message or a message defined in the Xn interface.
12. The method of claim 10,

    The DRX related information,

    And at least one parameter of a DRX start offset, a short term DRX cycle, and a long term DRX cycle.
13. The method of claim 10,

    The DRX related information,

    And DRC deactivation timer value of the secondary base station based on a quality of service (QoS).
14. The method of claim 10,

    The DRX related information,

    DRX parameter configuration method characterized in that the transmission is included in the capability information (capability information) of the terminal.
15. The method of claim 14,

    After transmitting the determined DRX parameter to the master base station,

    Modifying the DRX parameter when the application of the determined DRX parameter is denied; And

    Transmitting the modified DRX parameter to the master base station

    DRX parameter configuration method characterized in that it further comprises.
16. The method of claim 10,

    The DRX related information,

    And at least one candidate DRX parameter set configurable at the secondary base station.
17. The method of claim 16,

    The determined DRX parameter,

    And a candidate DRX parameter set selected from the at least one candidate DRX parameter set or an index of the selected candidate parameter set.
18. An apparatus for configuring a DRX (Discontinuous Reception) parameter for a terminal duplexed with a master base station and a secondary base station in a wireless communication system,

    A configuration unit configured to configure a first DRX parameter for the terminal;

    A transmitter for transmitting the information related to the first DRX parameter to the secondary base station; And

    Receiving unit for receiving the second DRX parameter determined from the information related to the first DRX parameter from the secondary base station

    Including,

    The transmitting unit,

    And a device for transmitting the received second DRX parameter to the terminal.
19. The method of claim 18,

    The information related to the first DRX parameter is

    And at least one parameter of a DRX start offset, a short term DRX cycle, and a long term DRX cycle.
20. The method of claim 18,

    The information related to the first DRX parameter is

    DRX parameter configuration apparatus comprising the capability information (capability information) of the terminal.

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