KR20150109970A - Method and apparatus for controlling transmission power in wireless communication system using dual connectivity - Google Patents

Abstract

Suggested are a method and an apparatus for controlling uplink transmission power in a wireless communications system using dual connectivity. A method for controlling transmission power by a terminal which performs wireless communications based on dual connectivity, includes a step of receiving a parameter related to the uplink power headroom of the terminal from a master base station of the dual connectivity, a step of transmitting power headroom information and maximum transmission power information for the serving cell of the terminal to at least one secondary base station of the dual connectivity and the mater base station based on the parameter, a step of calculating first maximum transmission power for a first serving cell group formed by the master base station and second maximum transmission power for a second serving cell group formed by at least one secondary base station based on the parameter, the power headroom information, and the maximum transmission power information, and a step of controlling the transmission power of an uplink signal to be transmitted to the at least one secondary base station and the baster base station based on the first maximum transmission power and the second maximum transmission power.

Description

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

The present invention relates to a method and apparatus for controlling transmission power of a mobile station by effectively scheduling uplink transmission of the mobile station when the mobile station is dual-connected via at least two base stations.

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 may be a master base station (MeNB) and the remaining base stations may be a secondary base station (SenB) have.

In the dual connection, each base station transmits a downlink signal through a bearer configured for one terminal and receives an uplink signal. 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 independently performs scheduling for the UE without any cooperation. Therefore, there is an uncertainty in scheduling because each base station can not know the information on the uplink transmission of other base stations. This causes very inefficient uplink resource allocation or scaling of frequent uplink transmission power. / Drop or a reception failure due to insufficient transmission power.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for effectively controlling uplink transmission power of a terminal having a dual connection in a wireless communication system using a dual connection scheme.

Another object of the present invention is to provide an apparatus for effectively controlling uplink transmission power in a wireless communication system using a dual connection scheme.

Another aspect of the present invention is to provide a method for efficiently scheduling uplink transmission of a terminal having a dual connection.

Another aspect of the present invention is to provide an apparatus for efficiently scheduling uplink transmissions of a UE having a dual connection.

According to an aspect of the present invention, there is provided a method of controlling transmission power by a terminal performing wireless communication based on dual connectivity, comprising: receiving a power headroom of the terminal from a master base station constituting the dual connection, And transmitting the remaining power information and the maximum transmission power information for each of the serving cells configured in the terminal to the master base station and the at least one secondary base station constituting the dual connection based on the parameter, , A first maximum transmission power for a first serving cell group configured by the master base station and a second serving cell group configured by the at least one secondary base station based on the parameter, the power remaining amount information and the maximum transmission power information, ≪ / RTI > calculating a second maximum transmit power for < RTI ID = 0.0 > 1 is based on the maximum transmit power and a second maximum transmission power may comprise the step of controlling the transmit power of an uplink signal transmitted by the master base station and the at least one secondary station.

According to another aspect of the present invention, a terminal performing wireless communication based on a dual connection receives a parameter related to an uplink power remaining amount from a master base station constituting a dual connection, and based on the parameter, A transmitting and receiving unit for transmitting power remaining amount information and maximum transmission power information for each serving cell configured in the terminal to at least one secondary base station constituting a connection, A processor for calculating a first maximum transmit power for a first serving cell group configured by the master base station and a second maximum transmit power for a second serving cell group configured by the at least one secondary base station, The first maximum transmit power and the second maximum transmit It is possible to control the transmission power of the uplink signal transmitted by the master base station and the at least one secondary base station on the basis of the force.

According to another aspect of the present invention, there is provided a method of scheduling a master base station for performing wireless communication based on a dual connection, the method comprising the steps of: Receiving a power residual amount information for each serving cell for each serving cell group configured in the terminal and maximum transmission power information for each of the serving cells configured in the terminal from the terminal, The first maximum transmission power for the first serving cell group configured by the master base station and the second maximum transmission power for the second serving cell group configured by the at least one secondary base station based on the information and the maximum transmission power information, Based on the first maximum transmit power, And scheduling the uplink transmission of the first terminal.

According to another aspect of the present invention, a master base station that performs wireless communication based on a dual connection is configured to transmit a parameter related to an uplink power remaining amount (Power Headroom) of a terminal configured with dual connectivity with at least one secondary base station And a transmitter and receiver for receiving power remaining amount information for each serving cell for each serving cell group configured in the terminal and maximum transmission power information for each of the serving cells configured in the terminal from the terminal, A first maximum transmission power for a first serving cell group configured by the master base station and a second maximum transmission power for a second serving cell group configured by the at least one secondary base station based on the power, Calculating a second maximum transmit power, and calculating the first maximum transmit power It may be based on scheduling uplink transmission of the UE.

In the dual connection, the master base station can efficiently schedule uplink transmissions of the UE through additional signaling, and the UE can efficiently control the uplink transmission power.

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 for explaining a residual power report of a UE having a dual connection.
FIG. 7 is a flowchart illustrating a method for scheduling uplink transmissions of a UE by a Node B configured with a dual connection according to an embodiment of the present invention. Referring to FIG.
FIG. 8 is a diagram illustrating a method for calculating the available remaining power of a terminal according to an embodiment of the present invention.
9 is a flowchart illustrating a method for scheduling uplink transmissions of a UE according to another embodiment of the present invention.
10 is a diagram illustrating a method for calculating the maximum transmit power of a terminal available for each of the serving cell groups provided by the master base station and the secondary base station according to another embodiment of the present invention.
11 is a block diagram illustrating a wireless communication system using a dual connection scheme according to 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 X2 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.

The dual connection is composed of an arbitrary UE, a master eNB (MeNB) and at least one secondary eNB (SeNB). The double connection can be divided into three options as shown in FIG. 5 according to the method of dividing the user plane data. In Fig. 5, 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 transmitted by dividing the data into two 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 in the protocol structure is the master base station (the second or third option), the protocol layer in the secondary base station should support segmentation or refinement. 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, the protocol structures for the dual connection in the RLC layer and above can be classified into the following various types.

The first type is a case where 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.

The second type is a case where RLC layers exist 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.

The third type is a case where 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 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.

Therefore, considering the above-mentioned options and types, the double connection can be configured as follows.

First, the S1-U interface has an end point not only in the master base station but also in the secondary base station, and when 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.

Next, it is assumed that the S1-U interface has an end point only in the master base station, 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. One of the PDCP layers 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 X2 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.

Hereinafter, Carrier Aggregation (CA) will be described in more detail. 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 used.

If the terminal forms a carrier aggregation, 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) to the terminal . 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). The serving cell set consists 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.

Adding, removing or reconfiguring secondary serving cells in a serving cell set is accomplished through an RRC connection reconfiguration procedure, which is dedicated signaling. Therefore, when a new serving cell is added to the 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.

Meanwhile, when a terminal supporting carrier aggregation performs communication with a plurality of base stations based on a dual connection, a plurality of aggregated serving cells may be provided by different base stations. A serving cell group (Master Cell Group) provided by the master base station among the serving cells configured in the UE is referred to as MCG, and a serving cell group (Secondary Cell Group) provided by the secondary base station is referred to as SCG. For example, when the main service cell, the first and second sub-serving cells are configured by carrier aggregation in the situation of a double connection, the main serving cell and the first sub-serving cell are connected to the MCG And the second sub-serving cell may be included in the SCG provided by the secondary base station.

6 is a diagram for explaining a residual power report of a UE having a dual connection.

Power Headroom (PH) refers to the amount of extra power that can be used for uplink transmission in addition to the power currently used by the UE for uplink transmission. For example, if the terminal has a maximum transmission power of 10W, which is an allowable range of uplink transmission power, and the current terminal uses 9W of power in a frequency band of 10Mhz, the terminal can additionally use 1W, . At this time, if the base station allocates a frequency band of 20 MHz to the terminal, the terminal requires 18 W (= 9 W × 2) of power. However, since the maximum transmission power of the UE is 10W, if the UE allocates a frequency band of 20MHz, the UE can not use all of the frequency bands, or the power of the UE can not be properly received due to the power shortage . In order to solve this problem, the UE reports to the BS that the power remaining amount is 1 W, so that the BS can perform scheduling within the remaining amount. This report is called the Power Headroom Report (PHR).

The residual power report of the terminal can be defined as two types (Type 1, Type 2). The residual power report of Type 1 is a case where the UE transmits 1) PUSCH without the PUCCH, 2) PUCCH and PUSCH simultaneously, and 3) the PUSCH is not transmitted with respect to the subframe i for the serving cell c . The remaining power report of Type 2 is used when the UE transmits 1) PUCCH and PUSCH simultaneously for subframe i for the main serving cell, 2) transmits PUSCH without PUCCH, 3) transmits PUCCH without PUSCH, 4) PUCCH or PUSCH may not be transmitted.

The above-described residual power report can be independently performed for a plurality of base stations communicating with a terminal based on a dual connection. 6 shows an example in which the terminal 660 enters an area where the service area of the macro cell F2 in the master base station 600 overlaps the service area of the small cell F1 in the secondary base station 610 Fig. In this case, the terminal 650 is provided with additional data service through the small cell F1 in the secondary base station 610 while maintaining the existing wireless connection and data service connection through the macro cell F2 in the master base station 600 A dual connection can be made to do so.

The terminal 650 configured with the dual connection through the master base station 600 and the secondary base station 610 is upgraded during one Transmission Time Interval (TTI) from each of the base stations 600 and 610 constituting the dual connection The transmission of the link signal can be instructed. In this situation, the terminal 650 configured with the dual connection transmits the serving cell (e.g., the serving cell) configured in the terminal 600 to each of the base stations 600 and 610 so that the base stations 600 and 610 can effectively support the uplink transmission of the terminal F1, and F2, respectively. At this time, type 2 residual power report can be performed to support simultaneous transmission of PUCCH and PUSCH.

The terminal 600 is also connected to each of the base stations 600 and 610 through the serving cells F1 and F2 configured in the terminal 600 so that each of the base stations 600 and 610 can obtain sufficient information about the transmission power of the terminal 660. [ ) Can be additionally reported. Here, the maximum transmission power information is a value calculated after considering the maximum power reduction (MPR) applied by the terminal 650 and the additional maximum power reduction (A-MPR).

Herein, the MPR is used to lower the maximum transmission power of the UE in consideration of general requirements regarding OOB (Out Of Band) emission and signal quality among the settings required for the UE. MPR is only an allowable amount, not a requirement. The following Table 1 shows the MPR for Power Classes 1 and 3 in the absence of a CA, and Table 2 shows the MPR for Power Class 3 in a CA configured scenario.

On the other hand, the A-MPR notifies the base station of the possibility of lowering the maximum transmission power of the terminal by signaling to the terminal. The A-MPR is a combination of E-UTRA bands, channel bandwidth, and transmission bandwidth, which are additionally required by the UE (for example, a spectrum emission mask ), And spurious emission). A-MPR is also an acceptable amount, not a requirement.

The terminal applies additional requirements for the spectral emission mask and spurious emissions signaled by the base station, regardless of whether the allowed MPR and A-MPR are used. Therefore, the base station can not know precisely which values the terminal uses as power back-off values, and only approximate estimation is possible. Therefore, in order to estimate the more accurate available power of the terminal, the terminal reports the maximum power information together with the power residual amount information to the base station for each serving cell configured in the terminal. The BS may transmit various information (e.g., a BSR (Buffer Status Report), an Estimated path-loss, a scheduling fairness, etc.) together with the power residual amount information reported from the UE, together with the maximum transmission power information, , Uplink transmission to the UE based on RRC setting (e.g., CA, Multiple Input Multiple Output (MIMO), simultaneous transmission of PUCCH and PUSCH), interference requirements, Scheduling.

If the UE performs only the PUSCH transmission without transmitting the PUCCH through the serving cell c included in one serving cell group, the UE calculates the PUSCH transmission power for the subframe i of the serving cell c included in the serving cell group P _{PUSCH, c} (i) as shown in Equation (1) below, and transmits the corresponding PUSCH.

값은 추정된 PL(Path-Loss)정보 (PL_c, 서빙셀c를 위한 PL추정값)에 대한 UL 전송에 대한 보상의 정도를 조절하는 값으로 j=0 또는 1인 경우, 상위 계층의 시그널링을 통해서

에서 서빙셀 c를 위해서 설정되고 j=2인 경우, 그 값은 항상

=1이다.

값은 전송되는 PUSCH 전송 포맷(e.g. MCS)에 따라 다이나믹하게 전송 파워를 제어하는 파라미터이다. f _c(i)은 DCI 포맷 0/4/3/3A내의 TPC 필드를 통해서 전송되는 다이나믹 파워 제어 명령을 수행하는 파라미터이다.Here, P _{CMAX, c} (i) Represents the maximum transmission power of the UE defined in the subframe i of the serving cell c included in one serving cell group. P _{O_PUSCH, c} (j) is a parameter composed of the sum of P _{O_NOMINAL_PUSCH, c} (j) and P _{O_UE_PUSCH, c} (j) provided from the upper layer. Here, j is an index value for distinguishing the characteristics of the corresponding PUSCH transmission. When j = 0, PUSCH transmission according to semi-static allocation, when j = 1, PUSCH transmission according to dynamic allocation, and when j = indicates a PUSCH transmission according to a response grant.

Value is a value for adjusting the degree of compensation for UL transmission for estimated PL (Path-Loss) information (PL _c , PL estimate for serving cell c). When j = 0 or 1, Through

Is set for the serving cell c and j = 2, the value is always

= 1.

Value is a parameter for dynamically controlling the transmission power according to the PUSCH transmission format (e.g., MCS) to be transmitted. f _c (i) is a parameter to perform dynamic power control command transmitted via the TPC field in the DCI format 0/4/3 / 3A.

In addition, if the UE performs PUSCH transmission with PUCCH transmission through a serving cell c included in one serving cell group, the UE transmits a PUSCH for subframe i of the serving cell c included in the serving cell group The power P _{PUSCH, c} (i) is allocated as shown in Equation (2) below and the corresponding PUSCH is transmitted.

는 P_CMAX,c(i)의 리니어 값(linear value)이다.here,

Is the linear value of P _{CMAX, c} (i).

In addition, if there is no PUSCH transmission through the serving cell c included in one serving cell group, in order to accumulate the TPC (Transmit Power Control) command for the PUSCH, The PUSCH transmission power P _{PUSCH, c} (i) for the subframe i of the cell c is given by the following equation (3).

Meanwhile, if a UE performs PUCCH transmission through a serving cell c included in one serving cell group, the UE calculates a PUCCH transmission power P for a subframe i of a serving cell c included in the serving cell group P _{PUCCH, c} (i) as shown in Equation (4) below, and transmits the corresponding PUCCH.

Also, if there is no PUCCH transmission through the serving cell c included in one serving cell group, the UE determines the PUCCH transmission power P _PUCCH for the subframe i of the serving cell c included in the serving cell group _{, c} (i) are assumed as the following Equation (5).

On the other hand, the SRS (Sounding Reference Signal) transmission power in the subframe i of the serving cell c included in one serving cell group is set as shown in Equation (6).

However, as shown in FIG. 6, uplink transmission can be independently instructed from the master base station 600 and the secondary base station 610 to the terminal 650 having the dual connection. In this case, since no coordination exists for data scheduling between the master base station 600 and the secondary base station 610, the master base station 600 transmits information on the uplink transmission of the secondary base station 610 Likewise, the secondary base station 610 can not know the information on the uplink transmission of the master base station 600. Therefore, the uplink resource may be inefficiently allocated to the terminal 650, or frequent power scaling / drop may occur. As a result, insufficient transmission power is used for the uplink transmission, Signal reception may fail. Accordingly, the present invention provides the following scheduling method for more efficient uplink scheduling when a dual connection is configured.

FIG. 7 is a flowchart illustrating a method of scheduling uplink transmissions of a UE according to an embodiment of the present invention. FIG. 8 is a flowchart illustrating a method of calculating available power of a UE according to an exemplary embodiment of the present invention. Fig.

As an example, referring to FIG. 7, a description will be given of a method in which available remaining power of a terminal is set in a network or divided into a predetermined ratio. In this case, the master base station uses a certain percentage of the remaining available power of the terminal through signaling in cooperation with the secondary base station. Hereinafter, the available power for the MCG among the remaining available power of the terminal is referred to as "? &Quot;, and the available power for the SCG is referred to as"? &Quot;.

The "? &Quot; value and the "?" Can be set through signaling (e.g., X2 interface) between the networks. The master base station providing the MCG and the secondary base station providing the SCG can obtain the scheduling guide for the uplink transmission of the UE having the dual connection through the signaling. Accordingly, inefficient uplink transmission of a UE, which may occur due to independent scheduling between base stations configured with a dual connection, can be more effectively controlled. The UE can set the two parameters (?,?, Etc.) through signaling of the upper layer and selectively control the uplink transmission power according to the uplink transmission environment of the UE.

Referring to FIG. 7, a master base station (MeNB) that performs wireless communication based on a dual connection receives an uplink power remaining amount of a UE connected to the master base station through at least one secondary base station (SeNB) (E.g., Power Headroom) (S700). For example, the parameters (alpha, beta, etc.) related to the power remaining amount may be determined by the master base station and transmitted (indicated) to the secondary base station or may be determined through negotiation between the master base station and the secondary base station. At this time, the master base station can transmit the remaining power report (PHR) together with the parameters (?,?, Etc.) and the configuration information to be instructed to the terminal for power control to the secondary base station. Then, the corresponding information (the parameter and the setting information) may be transmitted to the terminal in the form of an RRC message (signaling of an upper layer) (S710).

Upon receiving a parameter related to the uplink power reserve amount of the terminal from the master base station constituting the dual connection, the terminal transmits the residual power report format to the master base station and the secondary base station using the residual power report format or the converted residual power report format, (S720 and S730), respectively, for each serving cell configured in the serving cell. That is, the UE not only reports the power remaining amount information and the maximum transmission power information for the serving cell included in the serving cell group (MCG) provided by the master base station to the master base station but also reports to the secondary base station. Similarly, the power reserve amount information and the maximum transmission power information for the serving cell included in the serving cell group (SCG) provided by the secondary base station are reported not only to the secondary base station but also to the master base station.

Then, the UE calculates the maximum transmission power for the serving cell group (MCG) configured by the master base station and the maximum transmission power for the serving cell (MCG) configured by the secondary base station based on the parameters (alpha, beta, etc.) The maximum transmission power for the group (SCG) is calculated (S740).

Each base station also determines the maximum transmission power for the serving cell group (MCG) configured by the master base station based on the parameters (?,?, Etc.), the power remaining amount information and the maximum transmission power information, Calculate the maximum transmit power for the group (SCG). In step S750, each BS calculates an available total remaining power of the MS based on the power remaining amount information and the maximum transmission power information reported from the MS according to Equation (7).

Where P _CMAX denotes the maximum transmission power of the UE, P _{CMAX, c} denotes the maximum transmission power for the serving cell c included in the MCG, and P _{CMAX, j} denotes the maximum transmission power for the serving cell j included in the SCG . PHR _c (t) represents PHR information for the serving cell c included in the MCG, PHR _j (t) represents PHR information for the serving cell j included in the SCG, and P _remaining represents the available Represents the remaining power amount. If the P _remaining value is negative, the value may be 0 and the terminal may be considered as a power limited case in that case.

The UE and each of the base stations MeNB and SeNB calculates the serving cell group MCG and SCG using Equation (8) based on the _remaining available power amount (P _remaining ) of the UE and the above ratios (? Lt; / RTI > can be calculated.

Here, P _{CMAX and MCG} represent the maximum transmission power of the UE for the MCG, and P _{CMAX and SCG} represent the maximum transmission power of the UE for the SCG. If the P _Remaining value calculated through Equation (7) can be 0 or a negative number based on the negative PHR information, a predetermined rule, that is, a ratio of 1/2 of the maximum transmission power (P _CMAX ) The maximum transmission power of the cell group (P _CMAX / 2 = P _{CMAX, MCG or SCG} ). The ratio can of course be a different value (eg P _CMAX * 2/3 = P _{CMAX, MCG} or P _CMAX * 1/3 = P _{CMAX, SCG} ). In this case, equation (8) may not be performed and therefore the parameters alpha and beta are not valid.

FIG. 8 shows the available remaining power of the terminal, the maximum transmission power of the terminal for the MCG and the maximum transmission power of the terminal for the SCG, which are calculated based on Equations (7) and (8). In Figure 8 P-Max indicates the power class (Power Class) of the terminal, P _{UEMAX_c} denotes a maximum transmit power of the UE for the serving cell c in which a base station indicated through system information or an RRC message, P _{UEMAX_j} system information Or the maximum transmission power of the UE for the serving cell j indicated by the base station through the RRC message. The maximum transmission power (P _{CMAX, c} ) of the terminal according to the serving cell is calculated in consideration of the power reduction factors (Power reductions, for example, MPR, A-MPR, etc.) together with the P-Max and P _{UEMAX_c} (or P _{UEMAX_j} ) P _{CMAX, j} ) is determined. Power reduction component of the terminals are allocated for each serving cell is selected by the UE, the maximum transmission power due to the effect of the power decrease to the maximum transmit power (P _{CMAX, c)} and a serving cell j to the serving cell c (P _{CMAX , j} ) is determined. That is, the power reduction factors for each serving cell are set by the UE.

The UE calculates the power reserve amount (PHR_c, PHR_j) for each serving cell based on the determined maximum transmission power (P _{CMAX, c} , P _{CMAX, j} ) of the determined serving cell- However, the power remaining amount (PHR_c, PHR_j) of the terminal according to the serving cell is only the remaining power amount available for each serving cell, and is not the power remaining amount considering transmission on actual multiple serving cells from the terminal point of view. Therefore, the BS needs to calculate the actual _remaining power (P _remaining ) of the UE. To do so, the BS must know the maximum transmission power (P _{CMAX, c} , P _{CMAX, j} ) of the UE for each serving cell. It is possible to derive the maximum transmission power (P _CMAX ) of the UE through the maximum transmission power (P _{CMAX, c} , P _{CMAX, j} ) of the terminal for each serving cell. Therefore, the base station serving selbyeol power remaining amount of the terminal (PHR_c, PHR_j) and serving selbyeol maximum transmit power of the terminal (P _{CMAX, c,} P _{CMAX, j)} based in the available real power remaining amount of the terminal by using the equation (7) (P _remaining ).

The base station calculates the maximum transmission power P (P) of each of the serving cell groups MCG and SCG using Equation (8) based on the available _remaining power P _remaining in the mobile station (P _remaining ) _{CMAX, MCG} , P _{CMAX, SCG} ). At this time, the sum of the maximum transmission power (P _{CMAX, MCG} ) of the UE for the _MCG and the maximum transmission power (P _{CMAX, SCG} ) of the UE for the _SCG may be limited to not exceed the maximum transmission power (P _CMAX ) have.

As described above, when the maximum transmission power (P _{CMAX, MCG} , P _{CMAX, SCG} ) of a terminal for each serving cell group (MCG, SCG) is calculated, the master base station calculates the maximum transmission power (S760), the UE also controls the transmission power of the uplink signal to be transmitted to the master base station based on the maximum transmission power of the terminal for the MCG, so that the uplink signal is transmitted to the master base station (S770). Similarly to the master base station, the secondary base station also performs scheduling by instructing uplink transmission of the UE based on the maximum transmission power of the UE for the SCG (S780), and the terminal also transmits the uplink signal to the secondary base station And controls the transmission power of the uplink signal to be transmitted so that the uplink signal is transmitted to the secondary base station in step S790.

When the UE having the dual connection receives information on the ratio (?) Available for the MCG and the usable rate (?) For the SCG among the available residual power of the UE from the master base station, The transmission power (P _{CMAX, c} ) can be replaced with the maximum transmission power (P _{CMAX, MCG} ) of the terminal for MCG derived by Equation (8) and the maximum transmission power (P _{CMAX, SCG} ) of the terminal for _SCG . Specifically, the maximum transmission power (P _{CMAX, c} ) information of a terminal according to a serving cell is determined based on which serving cell group the corresponding serving cell is included in the uplink transmission and a combination of uplink channels and signals transmitted by the terminal during one TTI (P _{CMAX, MCG} ) of the UE for the _MCG and the maximum transmission power (P _{CMAX, SCG} ) of the UE for the _SCG, respectively, or may be used as it is. Therefore, the following new uplink transmission power control method for PUSCH / PUCCH / SRS transmission of a terminal having a dual connection can be considered for each uplink channel and signal.

For example, when at least one of the PUSCH and the PUCCH is transmitted in the subframe i of at least one serving cell included in each of the MCG and the SCG (i.e., the uplink channel is transmitted in both the MCG and the SCG) The maximum transmission power of the UE for the SCG may be used for the serving cell included in the MCG and the maximum transmission power of the UE for the SCG may be used for the serving cell included in the SCG. That is, as shown in Equation (9) _{, the} value of P _{CMAX, c in} Equations (1) to (6) is replaced with the maximum transmission power (P _{CMAX, MCG} ) of the terminal for MCG for the serving cell included in the MCG, The serving cell may be replaced with the maximum transmission power (P _{CMAX, SCG} ) of the UE for _SCG .

As another example, when at least one of the PUSCH and the PUCCH is transmitted in subframe i of at least one serving cell included in only one serving cell group among the MCG or SCG (i.e., only one serving cell group MCG SCG), a maximum transmit power for the at least one serving cell and a predetermined additional power may be used for the at least one serving cell. For example, as shown in Equation (10), the P _{CMAX, c} value of Equation (1) is directly used for transmission power control for the serving cell c included in the MCG, and an offset value P _{SG_offset} ) Can be added. The offset value may be set by the base station or may be a predetermined value.

As another example, if at least one of the PUSCH and the PUCCH is transmitted in subframe i of at least one serving cell included in only one serving cell group among the MCG or SCG (i.e., only one serving cell group MCG Or SCG), the maximum transmission power of the UE can be used for the at least one serving cell, as shown in Equation (11).

Meanwhile, if at least one of the PUSCH and the PUCCH is transmitted in the subframe i of at least one serving cell included in each of the MCG and the SCG (i.e., the MCG and the SCG At least one of the PUSCH and the PUCCH is transmitted in subframe i of at least one serving cell included in only one of the serving cell groups (i. E., If there is an uplink channel transmission in all) and only one of the MCG or SCG The accumulated TPC command received in DCI format 3 / 3A can be applied to prepare for the case of uplink channel transmission in the serving cell group (MCG or SCG). Equation (12) below shows a case where at least one of the PUSCH and the PUCCH is transmitted in the subframe i of at least one serving cell included in each of the MCG and the SCG (i.e., when there is an uplink channel transmission in both the MCG and the SCG) (13) shows that when at least one of the PUSCH and the PUCCH is transmitted in subframe i of at least one serving cell included in only one serving cell group out of MCGs or SCGs (i.e., only one serving cell group If there is an uplink channel transmission in the MCG or SCG).

는 P_{CMAX_K}의 linear scale이다.Here, P _{CMAX_K} represents the maximum transmission power of the UE for the specific serving cell group K. The K value is an index of the serving cell group, for example, K = 0 for MCG and K = 1 for SCG. P _{CMAX_K} can be estimated and calculated by the base station and the terminal through the above-described method.

_Is the linear scale of P _{CMAX_K} .

The uplink scheduling as described above can provide more efficient uplink transmission because uplink transmission with limited power can be avoided as compared with uplink scheduling which is performed completely independently.

FIG. 9 is a flowchart illustrating a method of scheduling uplink transmissions of a UE according to another embodiment of the present invention. FIG. 10 is a flowchart illustrating a method of scheduling uplink transmissions of a UE according to another embodiment of the present invention. Lt; RTI ID = 0.0 > available < / RTI >

Hereinafter, a method for scheduling uplink transmission on the basis of the transmission power of a terminal that can be used by reference to each base station (MeNB, SeNB) will be described as another embodiment. In this case, the master base station can use the maximum transmission power (P _{cmax, MCG} , P _{cmax, SCG} ) of the terminal that can be used as reference for each serving cell group (MCG, SCG) through signaling with the secondary base station . In this case, the maximum transmission power of the UE for the serving cell c included in the _MCG can be defined as P _{cmax, MCG, c} , and the maximum transmission power of the UE for the serving cell j included in the SCG is P _{cmax, SCG, j} . < / RTI > Hereinafter, it is assumed that the maximum transmission power (P _{cmax, MCG} ) of the UE that can be used as reference for the _MCG and the maximum transmission power (P _{cmax, SCG} ) of the UE that can be used as a reference for the _SCG are the same value.

Referring to FIG. 9, a master base station (MeNB) that performs wireless communication based on a dual connection receives power of uplink power of a terminal UE connected to the master base station through at least one secondary base station (SeNB) (S900). For example, the parameter related to the power remaining amount includes a maximum transmission power (P _{cmax, MCG} ) of a UE that can be used as a reference for _MCG and a maximum transmission power (P _{cmax, SCG} ). Here, the sum of the maximum transmission power (P _{cmax, MCG} ) of the UE that can be used as a reference for the _MCG and the maximum transmission power (P _{cmax, SCG} ) of the UE that can be used as a reference for the SCG, May be set by the base station (e.g., the master base station) so as not to exceed the transmit power (P _CMAX ).

As another example, the maximum transmit power (P _{cmax, MCG} ) of a UE that can be used as a reference for an _MCG and the maximum transmit power (P _{cmax, SCG} ) of a UE that can be used as a reference for the SCG are referred to as MCG (P _{cmax, MCG} ) of the UEs available for the SCG is less than or equal to the maximum transmission power (P _CMAX ) of the UE and the maximum transmission power (P _{cmax, SCG} ) May be determined through negotiation between the master base station and the secondary base station within a range of the maximum transmission power (P _CMAX ) of the master base station and the secondary base station. In this case, the maximum transmission power of the UEs allocated to each serving cell group MCG and SCG may be the maximum transmission power of the UE (P _CMAX ). Therefore, in this case, the maximum transmit power (P _{cmax, MCG} ) of the UE that can be used as a reference for the _MCG and the maximum transmit power (P _{cmax, SCG} ) of the UE that can be used as a reference for the _SCG The value may exceed the maximum transmission power of the terminal (P _CMAX ). Therefore, the value of P _{cmax, MCG} , P _cmax, and _SCG depends on the setting of the base station.

Meanwhile, the master base station can transmit the remaining power report (PHR) together with the parameters ( _{Pcmax, MCG} , _{Pcmax, and SCG} ) and the configuration information to be instructed to the terminal for power control to the secondary base station. Then, the corresponding information (the parameter and the setting information) may be transmitted to the terminal in the form of an RRC message (signaling of an upper layer) (S910).

Upon receiving a parameter related to the uplink power reserve amount of the terminal from the master base station constituting the dual connection, the terminal transmits the residual power report format to the master base station and the secondary base station using the residual power report format or the converted residual power report format, (S920, S930), and transmits the maximum transmission power information for each serving cell configured in the UE to the serving cell. That is, the UE not only reports the power remaining amount information and the maximum transmission power information for the serving cell included in the serving cell group (MCG) provided by the master base station to the master base station but also reports to the secondary base station. Similarly, the power reserve amount information and the maximum transmission power information for the serving cell included in the serving cell group (SCG) provided by the secondary base station are reported not only to the secondary base station but also to the master base station.

Each base station calculates a new parameter P 'based on the parameters ( _{Pcmax, MCG} , _{Pcmax, SCG} ) and the maximum transmission power information ( _{Pcmax, c} ) _{cmax, MCG} , P ' _{cmax, SCG} ).

Then, based on the new parameters (P ' _{cmax, MCG} , P' _{cmax, and SCG} ) and the information on the amount of remaining power for each serving cell by the serving cell group configured in the terminal, .

Here, P _Cmax represents the maximum transmission power of the UE, P ' _{cmax, MCG and c} represent the maximum transmission power of the UE for the serving cell c included in the MCG, and P' _{cmax and SCG,} Represents the maximum transmission power of the UE for the serving cell j. In addition, PHR _{MCG, c} (t) denotes a PHR information for the serving cell c contained in MCG, PHR _{SCG, j} (t) denotes the PHR information for the serving cell j included in the SCG, P _remaining is the terminal Lt; / RTI > Here, PHR _{MCG, c} (t) and PHR _{SCG, j} (t) can be derived based on P ' _{cmax, MCG, c} and P' _{cmax, SCG, j} , respectively.

When the maximum transmission power P ' _{cmax, MCG} , P' _{cmax, and SCG of} each mobile station group MCG and SCG is calculated, the master base station calculates the maximum transmission power P ' _{cmax and MCG for the MCG} , (S950), the terminal also controls the transmission power of the uplink signal to be transmitted to the master base station based on the maximum transmission power of the terminal for the MCG, so that the uplink signal is transmitted to the master base station To be transmitted to the master base station (S960). The secondary base station also performs scheduling by instructing the uplink transmission of the MS based on the maximum transmission power (P ' _{cmax, SCG} ) of the MS for the SCG in the same manner as the master base station (S970) And controls the transmission power of the uplink signal to be transmitted to the secondary base station based on the power so that the uplink signal is transmitted to the secondary base station in operation S980. Such uplink scheduling can provide more efficient uplink transmission by appropriately setting P _{cmax, MCG} , P _{cmax, and SCG} according to the network operation and environment

10 shows the available remaining power (P _remaining ) of the UE calculated based on Equations (14) and (15), the maximum transmission power (P ' _{cmax, MCG, c} ) of the UE for the serving cell c included in the _MCG, (P ' _{cmax, SCG, j} ) of the UE for the serving cell j included in the _SCG . 10, P-Max represents the power class of the UE, _{PUEMAX_c} represents the maximum transmission power of the UE for the serving cell c indicated by the BS through the system information or RRC message, and P _{UEMAX_j} represents the maximum transmission power of the UE Or the maximum transmission power of the UE for the serving cell j indicated by the base station through the RRC message. The maximum transmission power (P _{CMAX, c} ) of the terminal according to the serving cell is calculated in consideration of the power reduction factors (Power reductions, for example, MPR, A-MPR, etc.) together with the P-Max and P _{UEMAX_c} (or P _{UEMAX_j} ) P _{CMAX, j} ) is determined. Power reduction component of the terminals are allocated for each serving cell is selected by the UE, the maximum transmission power due to the effect of the power decrease to the maximum transmit power (P _{CMAX, c)} and a serving cell j to the serving cell c (P _{CMAX , j} ) is determined. That is, the power reduction factors for each serving cell are set by the UE.

Based on the maximum transmission power (P _{CMAX, c} , P _{CMAX, j} ) for each serving cell reported from the UE and the parameters (P _{cmax, MCG} , P _{cmax, SCG} ) determined through signaling between the base stations, each base station The maximum transmission power (P ' _{cmax, MCG, c} , P' _{cmax, SCG, j} ) for the serving cell (c, j) included in the serving cell group MCG and SCG can be calculated. Then, P ' _{cmax, MCG, c} , P' _{cmax, SCG, j} and The actual _remaining power (P _remaining ) of the UE can be calculated using Equation (15) based on the power remaining amount (PHR _{MCG, c} , PHR _{SCG, j} ) for each serving cell group reported from the UE.

In FIG. 10, for example, the maximum transmission power (P _{cmax, MCG} ) of the UE that can be used as reference for the _MCG and the maximum transmission power (P _{cmax, SCG} ) of the UE that can be used as a reference for the _SCG However _, when the sum of P _{cmax, MCG} , P _{cmax, and SCG} exceeds the value of P _CMAX , a PHR (Maximum _{Likelihood Ratio} ) is calculated according to the scheduling between the master base station and the secondary base station. _{MCG, c} and PHR _{SCG, j} may exceed the P _remaining value. In this case, power control may be required at the terminal.

When the UE having the dual connection is set up with information on P _{cmax, MCG} , P _{cmax, and SCG} from the master base station through RRC signaling, the maximum transmission power (P _{CMAX, c} ) P ' _{cmax, MCG} or P' _{cmax, SCG} in the same way as Therefore, the following new uplink transmission power control method for PUSCH / PUCCH / SRS transmission of a terminal having a dual connection can be considered for each uplink channel and signal.

For example, if at least one of the PUSCH and the PUCCH is transmitted in the subframe i of at least one serving cell included in each of the MCG and the SCG (i.e., if there is an uplink channel transmission in both the MCG and the SCG) The maximum transmission power of a terminal for each serving cell is replaced with the maximum transmission power of a terminal for each serving cell for each serving cell group and is used to perform uplink transmission control of a terminal for each serving cell. For example, when only the PUSCH transmission is performed without transmitting the PUCCH in the serving cell c included in the MCG, the value of P _{CMAX, c in} Equation (1) can be replaced with the following Equation (16).

As another example, when at least one of the PUSCH and the PUCCH is transmitted in subframe i of at least one serving cell included in only one serving cell group among the MCG or SCG (i.e., only one serving cell group MCG If there is an uplink channel transmission in the SCG), a predetermined additional power may be used for the at least one serving cell. For example, when only PUSCH transmission is performed without transmitting PUCCH in the serving cell c included in the MCG, an offset value (P _{SG -} Offset) for additional allocation of residual power may be added to _Equation ( ₁₆ ) as follows. The offset value may be set by the base station or may be a predetermined value.

As another example, if at least one of the PUSCH and the PUCCH is transmitted in subframe i of at least one serving cell included in only one serving cell group among the MCG or SCG (i.e., only one serving cell group MCG Or SCG), then the maximum transmit power for the serving cell included in that serving cell group may be used for the at least one serving cell. For example, when only PUSCH transmission is performed without PUCCH transmission in the serving cell c, the following Equation 18 is obtained.

Meanwhile, if at least one of the PUSCH and the PUCCH is transmitted in the subframe i of at least one serving cell included in each of the MCG and the SCG (i.e., the MCG and the SCG are both transmitted in the MCG and the SCG, And at least one of the PUSCH and the PUCCH is transmitted in subframe i of at least one serving cell included in only one serving cell group of the MCG or SCG (i.e., only one serving The accumulated TPC command received in the DCI format 3 / 3A can be applied for the subsequent PUSCH / PUCCH transmission as shown in Equation (19) below in order to prepare for the uplink channel transmission in the cell group (MCG or SCG) have.

11 is a block diagram illustrating a wireless communication system using a dual connection scheme according to the present invention.

11, a wireless communication system using a dual connection scheme according to the present invention includes a master base station 1110, at least one secondary base station 1120, and a terminal 1130.

The processor 1111 of the master base station 1110 determines parameters related to the uplink power remaining amount of the terminal 1130 having the dual connection with the at least one secondary base station 1120. Then, the transmitting / receiving unit 1112 of the master base station 1110 transmits the determined parameters to the secondary base station 1120. The processor 1111 of the master base station 1110 instructs the secondary base station 1120 to set the determined parameter or the parameters related to the uplink power remaining amount of the terminal 1130 with the secondary base station 1120 . ≪ / RTI > At this time, the parameter may be transmitted through the X2 interface.

The transmitting and receiving unit 1112 of the master base station 1110 transmits the parameters to the terminal 1130 and receives the power remaining amount information and the maximum transmission power information for each of the serving cells configured in the terminal 1130 from the terminal 1130 .

Then, the processor 1111 of the master base station 1110 determines the maximum transmission power for the serving cell group MCG configured by the master base station 1110 based on the parameter, the remaining power amount information, and the maximum transmission power information, Calculates the maximum transmission power for the serving cell group (SCG) configured by the base station 1120, and schedules the uplink transmission of the UE 1130 based on the calculated maximum transmission powers. At this time, the master base station 1110 may use Equations (7) and (8) described above or Equations (14) and (15).

When the transmitting / receiving unit 1121 of the secondary base station 1120 receives a parameter related to the uplink power remaining amount of the terminal 1130 from the master base station 1110, the processor 1122 of the secondary base station 1120 applies the received parameter Or negotiates with the master base station 1110 to determine a parameter to be finally used. When the transmitter / receiver 1121 of the secondary base station 1120 receives the power remaining amount information and the maximum transmission power information for each serving cell configured in the terminal 1130 from the terminal 1130, the processor 1120 of the secondary base station 1120 1122 may use Equations 7 and 8 described above, as well as the master base station 1110, or use Equations 14 and 15 to determine the maximum transmit power for the serving cell group MCG configured by the master base station 1110, Calculates the maximum transmission power for the serving cell group (SCG) configured by the base station 1120, and schedules the uplink transmission of the UE 1130 based on the calculated maximum transmission powers.

The transceiver 1131 of the terminal 1130 receives a parameter related to the uplink power remaining amount from the master base station 1110 and transmits the parameter related to the uplink power remaining amount to the terminal 1130 calculated by the processor 1132 of the terminal 1130, To the master base station 1110 and the secondary base station 1120, power remaining amount information and maximum transmission power information for each serving cell configured in the serving cell. At this time, the parameter may be received via the RRC message, and the ratio of the available available power for the serving cell group (MCG) provided by the master base station 1110 to the secondary base station 1120, (SCG) provided by the serving cell group < RTI ID = 0.0 > (SCG). ≪ / RTI > Alternatively, the parameter may include information on the maximum transmission power of the UE that can be used as a reference for the MCG and the maximum transmission power of the UE that can be used as a reference for the MCG.

The processor 1132 of the UE 1130 transmits the maximum transmission power for the serving cell group MCG configured by the master base station 1110 and the maximum transmission power for the serving cell group MCG based on the parameter, (SCG) configured by the base station 1120 and calculates the maximum transmission power for the serving cell group SCG configured by the transmission power of the uplink signal to be transmitted to the master base station 1110 and / or the secondary base station 1120 based on the calculated maximum transmission powers . At this time, the processor 1132 of the terminal 1130 may use the above-described Equations (9) to (13) or the Equations (16) to (19).

For example, when at least one of the PUSCH and the PUCCH is transmitted through at least one serving cell in the MCG and the SCG, the processor 1132 of the UE 1130 transmits the maximum transmission power for the MCG to the serving cell included in the MCG And use the maximum transmit power for the SCG for the serving cell included in the SCG. In addition, when at least one of the PUSCH and the PUCCH is transmitted through at least one serving cell in the MCG or the SCG, a maximum transmission power and a predetermined additional power for the at least one serving cell are used for the at least one serving cell Or may use the maximum transmit power of the terminal 1130 for the at least one serving cell. In addition, if there is no PUSCH and PUCCH transmission in the MCG and the SCG, the accumulated TPC command received in DCI format 3 / 3A may be applied in order to prepare for the case of PUSCH and / or PUCCH being transmitted thereafter.

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 . 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 (18)

A method for controlling transmission power by a terminal performing wireless communication based on Dual Connectivity,
Receiving a parameter related to an uplink power remaining amount (Power Headroom) of the terminal from a master base station constituting the dual connection;
Transmitting power reserve amount information and maximum transmission power information for each serving cell configured in the terminal to the master base station and at least one secondary base station constituting the dual connection based on the parameter;
A first maximum transmission power for a first serving cell group configured by the master base station and a second serving cell group configured by the at least one secondary base station based on the parameter, the power remaining amount information, and the maximum transmission power information Calculating a second maximum transmit power for the second transmit power; And
Controlling transmission power of an uplink signal to be transmitted to the master base station and the at least one secondary base station based on the first maximum transmission power and the second maximum transmission power
/ RTI > The method according to claim 1,
Wherein the parameter comprises:
(RRC) message, wherein the RRC message is received through an RRC (Radio Resource Control) message. The method according to claim 1,
Wherein the parameter comprises:
And a ratio of available power for the first serving cell group and a ratio available for the second serving cell group among the available remaining power of the terminal. The method of claim 3,
The information on the ratio is,
Wherein the at least one secondary base station is determined by the master base station and transmitted to the at least one secondary base station or through negotiation between the master base station and the at least one secondary base station. The method according to claim 1,
In the step of controlling the transmission power,
When at least one of a Physical Uplink Shared Channel (PUSCH) and a Physical Uplink Control Channel (PUCCH) is transmitted through at least one serving cell in each of the first serving cell group and the second serving cell group, Power is used for the serving cell included in the first serving cell group and the second maximum transmission power is used for the serving cell included in the second serving cell group. The method according to claim 1,
In the step of controlling the transmission power,
If at least one of a Physical Uplink Shared Channel (PUSCH) and a Physical Uplink Control Channel (PUCCH) is transmitted through at least one serving cell in the first serving cell group or the second serving cell group, And using a maximum transmit power and a predetermined additional power for the at least one serving cell. The method according to claim 1,
In the step of controlling the transmission power,
When at least one of a Physical Uplink Shared Channel (PUSCH) and a Physical Uplink Control Channel (PUCCH) is transmitted through at least one serving cell in the first serving cell group or the second serving cell group, Is used for the at least one serving cell. Receiving a parameter related to an uplink power reserve amount (Power Headroom) from a master base station constituting a dual connection, and transmitting, to at least one secondary base station constituting the dual connection with the master base station, A transmitting / receiving unit for transmitting power remaining amount information and maximum transmission power information for each of the serving cells configured in the serving cell; And
A first maximum transmission power for a first serving cell group configured by the master base station and a second serving cell group configured by the at least one secondary base station based on the parameter, the power remaining amount information, and the maximum transmission power information Lt; RTI ID = 0.0 > a <
Lt; / RTI >
The processor comprising:
And controls transmission power of an uplink signal to be transmitted to the master base station and the at least one secondary base station based on the first maximum transmission power and the second maximum transmission power. 9. The method of claim 8,
The transmitting /
And receives a parameter related to the power remaining amount through an RRC (Radio Resource Control) message. 9. The method of claim 8,
Wherein the parameter comprises:
And a rate available for the first serving cell group and a ratio available for the second serving cell group among the available remaining power of the terminal. 11. The method of claim 10,
The information on the ratio is,
Is determined by the master base station and is transmitted to the at least one secondary base station or through negotiation between the master base station and the at least one secondary base station. 9. The method of claim 8,
The processor comprising:
When at least one of a Physical Uplink Shared Channel (PUSCH) and a Physical Uplink Control Channel (PUCCH) is transmitted through at least one serving cell in each of the first serving cell group and the second serving cell group, Power for the serving cell included in the first serving cell group and uses the second maximum transmission power for the serving cell included in the second serving cell group. 9. The method of claim 8,
The processor comprising:
If at least one of a Physical Uplink Shared Channel (PUSCH) and a Physical Uplink Control Channel (PUCCH) is transmitted through at least one serving cell in the first serving cell group or the second serving cell group, Using the maximum transmit power and predetermined additional power for the at least one serving cell. 9. The method of claim 8,
The processor comprising:
When at least one of a Physical Uplink Shared Channel (PUSCH) and a Physical Uplink Control Channel (PUCCH) is transmitted through at least one serving cell in the first serving cell group or the second serving cell group, Is used for the at least one serving cell. A method for scheduling a master base station that performs wireless communication based on Dual Connectivity,
Determining a parameter related to an uplink power remaining amount (Power Headroom) of a terminal doubly connected through the master base station and at least one secondary base station;
Receiving power residual amount information for each serving cell for each serving cell group configured in the terminal and maximum transmission power information for each of the serving cells configured in the terminal;
A first maximum transmission power for a first serving cell group configured by the master base station and a second serving cell group configured by the at least one secondary base station based on the parameter, the power remaining amount information, and the maximum transmission power information Calculating a second maximum transmit power for the second transmit power; And
Scheduling uplink transmission of the UE based on the first maximum transmission power;
. ≪ / RTI > 16. The method of claim 15,
After determining the parameter,
And transmitting the parameter to the UE through an RRC (Radio Resource Control) message. 16. The method of claim 15,
Wherein the parameter comprises:
Wherein the scheduling information is determined through negotiation between the master base station and the at least one secondary base station. A processor for determining a parameter related to an uplink power remaining amount (Power Headroom) of a terminal having a dual connectivity with at least one secondary base station;
A transmission / reception unit for receiving power remaining amount information for each serving cell for each serving cell group configured in the terminal and maximum transmission power information for each of the serving cells configured in the terminal,
Lt; / RTI >
The processor comprising:
A first maximum transmission power for a first serving cell group configured by the master base station and a second serving cell group configured by the at least one secondary base station based on the parameter, the power remaining amount information, and the maximum transmission power information And for scheduling uplink transmissions of the UE based on the first maximum transmit power.

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