KR102103343B1 - Method and apparatus of transmitting data in heterogeneous network wireless communication system - Google Patents

Abstract

The present invention relates to a data transmission apparatus and method in a heterogeneous network wireless communication system.
In this specification, receiving radio bearer configuration information for a dual connection from a master base station, configuring the same radio bearer corresponding to both the master base station and at least one secondary base station in the terminal based on the radio bearer configuration information, the same A method of transmitting uplink data, comprising transmitting data of a primary logical channel mapped to a radio bearer to a master base station, and transmitting data of a secondary logical channel mapped to the same radio bearer to at least one secondary base station. It starts.

Description

METHOD AND APPARATUS OF TRANSMITTING DATA IN HETEROGENEOUS NETWORK WIRELESS COMMUNICATION SYSTEM in a heterogeneous network wireless communication system

The present invention relates to wireless communication, and more particularly, to a data transmission apparatus and method in a heterogeneous network wireless communication system.

In particular areas, such as hotspots inside a cell, there is a particularly high demand for communication, and in certain areas, such as a cell edge or a coverage hole, reception sensitivity of radio waves may decrease. With the development of wireless communication technology, small cells in a macro cell, for example a pico cell, for the purpose of enabling communication in areas such as hot spots, cell boundaries, and coverage holes. (Pico Cell), Femto Cell (Femto Cell), Micro Cell (Micro Cell), remote radio head (remote radio head: RRH), relay (relay), repeater (repeater), etc. are installed together. This network is called a heterogeneous network (HetNet). In a heterogeneous network environment, macro cells are relatively large cells, and small cells such as femto cells and pico cells are small cells. In a heterogeneous network environment, overlapping coverage occurs between multiple macro cells and small cells.

A radio bearer based on an Evolved Packet System bearer (EPS) that is distinguished from each other through two or more base stations may be configured in the terminal. This is called dual connectivity. In other words, dual connection may be an operation in which a terminal consumes radio resources provided by at least two different network points. Here, the at least two different network points may be a plurality of base stations physically or logically divided. One of the plurality of base stations may be a macro base station, and the other base stations may be small base stations.

In a dual connection, each base station transmits downlink data through an Evolved Packet System bearer (EPS) or a radio bearer (RB) configured for one UE and receives uplink data. . At this time, one RB may be configured in one base station or terminal, or the same single RB may be configured in two or more different base stations or terminals.

In the latter case, the terminal may perform uplink data transmission to two or more different base stations. However, for this purpose, parameters for uplink data transmission must be clearly defined in a dual connection, and a method for controlling uplink data transmission is required.

The technical problem of the present invention is to provide a data transmission apparatus and method in a heterogeneous network wireless communication system.

Another technical problem of the present invention is to provide configuration information for configuring a dual connection between a terminal and two or more different base stations.

Another technical problem of the present invention is to provide a method for controlling uplink data transmission of a terminal to two or more different base stations.

According to an aspect of the present invention, a method is provided in which a terminal transmits uplink data to a master base station (master eNodeB: MeNB) and at least one secondary base station (SeNB) in a wireless communication system. The method includes receiving radio bearer configuration information for dual connectivity from the master base station, and corresponding to both the master base station and the at least one secondary base station based on the radio bearer configuration information. Configuring the same radio bearer to the terminal, transmitting data of a master logical channel (LC) mapped to the same radio bearer to the master base station, and being mapped to the same radio bearer And transmitting data of a secondary logical channel to the at least one secondary base station.

According to another aspect of the present invention, there is provided a terminal for transmitting uplink data to a master base station (master eNodeB: MeNB) and at least one secondary base station (SeNB) in a wireless communication system. The terminal corresponds to both the master base station and the at least one secondary base station, based on the receiver and the radio bearer configuration information, which receives radio bearer configuration information for dual connectivity from the master base station. A radio bearer setting unit configured to configure the same radio bearer to the terminal, and generates data of a master logical channel (LC) mapped to the same radio bearer, and a secondary unit mapped to the same radio bearer (secondary) ) A data generation unit for generating data of a logical channel, and a transmission unit for transmitting data of the primary logical channel to the master base station, and transmitting data of the secondary logical channel to the at least one secondary base station.

When the UE configures the MAC PDU (s), a mapping relationship between uplink grants for serving cells configured for each base station and an RB configured for each base station and a corresponding logical channel may be considered. And the terminal can support QoS for each base station through uplink by performing uplink scheduling based on the mapping relationship.

1 is a view showing a network structure of a wireless communication system to which the present invention is applied.
2 is a block diagram showing a radio protocol structure for a user plane.
3 is a block diagram showing a radio protocol structure for a control plane.
4 is a view showing the structure of a bearer service in a wireless communication system to which the present invention is applied.
5 is a view showing a dual connection situation of a terminal to which the present invention is applied.
FIG. 6 is an exemplary diagram of subdividing an example of uplink transmission in a dual connection to which the present invention is applied at each layer level.
7 is an exemplary diagram of subdividing another example of uplink transmission in a dual connection to which the present invention is applied at each layer level.
8 is an exemplary diagram of subdividing another example of uplink transmission in a dual connection to which the present invention is applied at each layer level.
9 is an explanatory diagram showing an example of a method for performing uplink scheduling of a terminal to which the present invention is applied.
10 is an explanatory diagram showing another example of a method of performing uplink scheduling of a terminal to which the present invention is applied.
11 is a flowchart illustrating a method of transmitting uplink data in a heterogeneous network wireless communication system according to an example of the present invention.
12 is an explanatory diagram showing a method of performing uplink scheduling of a terminal according to an example of the present invention.
13 is an explanatory diagram showing a method of performing uplink scheduling of a terminal according to another example of the present invention.
14 is an explanatory diagram showing a method of performing uplink scheduling of a terminal according to another example of the present invention.
15 is a block diagram of a terminal and a base station according to an example of the present invention.

Hereinafter, in the present specification, contents related to the present invention will be described in detail through exemplary drawings and examples together with the contents of the present invention. It should be noted that in adding reference numerals to the components of each drawing, the same components have the same reference numerals as possible even though they are displayed on different drawings. In addition, in describing embodiments of the present specification, when it is determined that detailed descriptions of related well-known structures or functions may obscure the subject matter of the present specification, detailed descriptions thereof will be omitted.

In addition, this specification is described for a wireless communication network, the work performed in the wireless communication network is performed in the process of controlling the network and transmitting data in a system (for example, a base station) that is in charge of the wireless communication network, or The operation can be performed at the terminal coupled to the network.

1 is a view showing a network structure of a wireless communication system to which the present invention is applied.

FIG. 1 shows a network structure of an Evolved-Universal Mobile Telecommunications System (E-UMTS) 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 advanced (LTE-A) 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 , OFDM-TDMA, OFDM-CDMA can use a variety of multiple access techniques.

Referring to Figure 1, E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network) is a base station that provides a user equipment (UE: User Equipment, 10) a control plane (CP: Control Plane) and a user plane (UP: User Plane) (eNB: evolved NodeB, 20).

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

Base station 20 generally refers to a station (station) that communicates with the terminal 10, BS (Base Station), BTS (Base Transceiver System), access point (Access Point), femto base station (femto-eNB), pico It may be referred to as other terms such as a base station (pico-eNB), a home base station (Home eNB), and a relay. The base stations 20 are physically connected through an optical cable or a Digital Subscriber Line (DSL), and can exchange signals or messages with each other through an X2 interface. Hereinafter, the description of the physical connection will be omitted and the logical connection will be described. As shown in Figure 1, the base station 20 is connected to the Evolved Packet Core (EPC) 30 through the 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 MME with the context information of the terminal 10 and the information for supporting the mobility of the terminal 10 through the S1-MME interface. In addition, data to be serviced to and from each terminal 10 is exchanged with the S-GW through the S1-U interface.

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

E-UTRAN and EPC (30) are integrated to be called Evolved Packet System (EPS), and all traffic flows from the radio link that the terminal 10 connects to the base station 20 to the PDN connecting to the service entity are IP. (Internet Protocol).

The radio interface between the terminal 10 and the base station 20 is called "Uu interface". The layers of the radio interface protocol between the terminal 10 and the network are the first layer (L1) defined in a 3GPP (3rd Generation Partnership Project) type wireless communication system (UMTS, LTE, LTE-Advanced, etc.), It may be divided into 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 radio resource control (RRC) layer located in the third layer exchanges RRC messages to the terminal. Radio resources are controlled between (10) and the network.

2 is a block diagram showing a radio protocol architecture for a user plane, and FIG. 3 is a block diagram showing a radio protocol architecture 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.

2 and 3, a physical layer (PHY (physical) layer) provides an information transfer service (information transfer service) to the upper layer by using a physical channel (physical channel). The physical layer is connected to the upper layer, the medium access control (MAC) layer, and through a transport channel. Data is transferred through the transport channel between the MAC layer and the physical layer. Transport channels are classified according to how data is transmitted through a wireless interface.

In addition, data is transferred through physical channels between different physical layers (ie, between the physical layers of the transmitter and the receiver). The physical channel can be modulated by an orthogonal frequency division multiplexing (OFDM) method, and utilizes time, frequency, and space generated by a plurality of antennas as radio resources.

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

The MAC layer can perform multiplexing or demultiplexing between a logical channel and a transport channel and a transport block provided as a physical channel on a transport channel of a MAC service data unit (MAC SDU) belonging to the logical channel. The MAC layer provides a service to a radio link control (RLC) layer through a logical channel. The logical channel can be divided into a control channel for transmitting control region information and a traffic channel for transferring user region information. For example, as services provided from a MAC layer to a higher layer, there is data transfer or radio resource allocation.

The functions of the RLC layer include concatenation, segmentation and reassembly of RLC SDUs. The RLC layer is a transparent mode (TM: Transparent Mode), an unacknowledged mode (UM), and an acknowledgment mode (AM: AM) to ensure various quality of service (QoS) required by a radio bearer (RB). It provides three operation modes: Acknowledged Mode.

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

RLC SDUs are supported in various sizes, for example, in units of bytes. RLC Protocol Data Units (PDUs) are defined only when a transmission opportunity is notified from a lower layer (eg, MAC layer) and are transmitted to a lower layer. The transmission opportunity can be informed 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 user data transfer, header compression and ciphering, and control plane data transfer and encryption / integrity protection.

The RRC layer is responsible for control of logical channels, transport channels, and physical channels in connection with configuration, re-configuration, and release of RBs. 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 terminal and a network. RB configuration 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. RB may be divided into SRB (Signaling RB) and DRB (Data RB). SRB is used as a path for transmitting RRC messages and non-access stratum (NAS) messages in the control plane, and DRB is used as a path for transmitting user data in the user plane.

The NAS (Non-Access Stratum) layer located above the RRC layer performs functions such as session management and mobility management. If there is an RRC connection (RRC Connection) between the RRC layer of the terminal and the RRC layer of the E-UTRAN, the terminal is in the RRC connected state (RRC connected state), otherwise it is in the RRC idle state (RRC idle state) do.

In order for the terminal to transmit user data (eg, IP packet) to the external Internet network or to receive user data from the external Internet network, it exists between mobile communication network entities existing between the terminal and the external Internet network. Resources must be allocated to multiple paths. The path through which resources are allocated and transmitted and received between the mobile communication network entities is called a bearer.

4 is a view showing the structure of a bearer service in a wireless communication system to which the present invention is applied.

4 shows a path in which an end-to-end service is provided between the terminal and the Internet network. Here, the end-to-end service means a service in which the terminal requires a path between the terminal and the P-GW (EPS Bearer) and a path between the P-GW and the outside (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 delivers data to the external Internet network, the terminal first transmits the data to the base station (eNB) through the RB on the radio. 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 through the S5 / S8 bearer, and finally the data is delivered to the destination existing in the P-GW and the external Internet network through an external bearer.

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

In this way, in a wireless communication system, each bearer is defined for each interface, thereby guaranteeing independence between interfaces. The bearer in each interface will be described in more detail as follows.

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

The S5 / S8 bearer is a bearer of the S5 / S8 interface. Both S5 and S8 are bearers that exist on the interface between S-GW and 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 that the S-GW roams into (Visited PLMN), and the operator that the P-GW originally subscribed to (Home) PLMN).

The E-RAB uniquely expresses the concatenation of the S1 bearer and the 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 a bearer at the interface between the base station and the S-GW.

RB means two types of data: RB (Data Radio Bearer) and signaling RB (Signaling Radio Bearer), but in the present invention, RB is a DRB provided in the Uu interface to support a user's service. . Therefore, RB expressed without distinction is distinct from SRB. RB is a path through which data of the user plane is transmitted, and SRB is a path through which data of the control plane such as an RRC layer and NAS control messages is transmitted. There is a one-to-one mapping between RB, E-RAB and EPS bearer.

EPS bearer types include a default bearer and a dedicated bearer. When the terminal accesses the wireless communication network, an IP address is assigned, and a PDN connection is generated, and 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) through the default bearer and then uses a service (for example, VoD, etc.) that cannot properly receive QoS with the default bearer, on-demand A dedicated bearer is created. In this case, the dedicated bearer may be set to a different QoS from the bearer already set. QoS decision parameters applied to a dedicated bearer are provided by PCRF (Policy and Charging Rule Function). When creating a dedicated bearer, the PCRF can receive the user's subscription information from the Subscriber Profile Repository (SPR) to determine QoS decision parameters. For example, up to 15 dedicated bearers may be generated, and 4 of the 15 are not used in the LTE system. Therefore, up to 11 dedicated bearers can be created.

EPS bearer includes QCI (QoS Class Identifier) and ARP (Allocation and Retention Priority) as basic QoS decision parameters. EPS bearers are divided into GBR (Guaranteed Bit Rate) bearers and non-GBR bearers according to the QCI resource type. The default bearer is always set as a non-GBR type bearer, and the dedicated bearer can be set as a GBR type or a 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 should provide as a whole is defined as an EPS bearer, each QoS is defined for each interface. Each interface sets a bearer according to the QoS that it should provide.

5 is a diagram showing an example of a dual connection situation of a terminal to which the present invention is applied. This is the case for inter-frequency dual connections.

In FIG. 5, as an example, the UE 550 enters an overlapping region where the service area of the macro cell F2 in the macro base station 500 and the service area of the small cell F1 in the small base station 510 overlap. The case is shown. The macro base station 500 may be referred to as a master eNB (MeNB), and the small base station 510 may be referred to as a secondary eNB (SeNB).

In this case, in order to support additional data services through the small cell F1 in the small base station 510 while maintaining the existing wireless connection and data service connection through the macro cell F2 in the macro base station 500, the network A dual connection is configured for the terminal 550. Accordingly, user data arriving at the macro base station 500 may be transmitted to the terminal 550 through the small base station 510. Specifically, the F2 frequency band is allocated to the macro base station 500, and the F1 frequency band is allocated to the small base station 510. The terminal 550 may receive a service through the F2 frequency band from the macro base station 500, and may receive a service through the F1 frequency band from the small base station 510. In the above example, the macro base station 500 is described as using the F2 frequency band, and the small base station 510 uses the F1 frequency band, but is not limited thereto, and the macro base station 500 and the small base station 510 have the same F1 or F2 frequency. Bands can also be used.

FIG. 6 is an exemplary diagram of subdividing an example of uplink transmission in a dual connection to which the present invention is applied at each layer level.

Referring to FIG. 6, both a master base station (MeNB) providing a macro cell and a secondary base station (SeNB) providing a small cell include PDCP, RLC, MAC and PHY layers. The first RB (# 1 RB) is configured through the PDCP layer and the RLC layer of the terminal and the PDCP layer and the RLC layer of the master base station, and the second RB (# 2 RB) is the PDCP layer of the terminal, the RLC layer, and the secondary base station. It consists of PDCP layer and RLC layer. The RBs may be configured to include a part of the MAC layer related to logical channel configuration. The UE is connected to the P-GW through the first EPS bearer (# 1 EPS bearer), and is connected to the P-GW through the second EPS bearer (# 2 EPS bearer). In this way, each base station receives uplink data through an EPS bearer or RB (# 1 RB and # 2 RB) configured in each base station for one UE is also referred to as a CN network (Core Network split).

7 is an exemplary diagram of subdividing another example of uplink transmission in a dual connection to which the present invention is applied at each layer level.

Referring to FIG. 7, an uplink transmission in a bearer split structure is illustrated. In the bearer split, one RB is configured through a plurality of base stations, and the UE divides and transmits uplink data through the one RB into one or two flows (or more flows). Or, when one RB is configured between base stations and a terminal based on dual connectivity, a logical channel group corresponding to the one RB and defined for each of the base stations may be defined as a bearer split. Or, the same radio bearer corresponding to all of a plurality of base stations may be defined as a bearer split. Since information is transmitted through a plurality of flows, the bearer split is referred to as multi flow, multiple nodes (eNB) transmission, and inter-eNB carrier aggregation. You can.

In the case of a bearer split, each base station may include a PDCP layer, a MAC layer, and an RLC layer, but a layer in charge of flow control is included in only one base station (ie, a master base station). If the layer responsible for the flow control is the PDCP layer, the PDCP layer is included only in the master base station.

The MAC layer of each base station transmits information on the amount of data and transmission opportunities to the RLC layer. The RLC layer configures the RLC PDU by dividing or combining RLC SDU data received from the PDCP layer located in the same base station based on information received from the MAC layer. Thereafter, the MAC layer receives the RLC PDU configured in the RLC layer from the RLC layer in the form of a MAC SDU. However, in the case of a bearer split, although the RLC layer of the secondary base station processes data according to the data amount and the transmission opportunity required by the MAC layer of the secondary base station, information on the processed data amount and transmission opportunity exists above the RLC layer. The master base station should inform the layer in charge of flow control.

To this end, the PDCP layer of the master base station may be connected to the RLC layer of the secondary base station using the Xn interface protocol, as shown in FIG. 7. At this time, the Xn interface protocol is defined as an interface between MeNB and SeNB. The Xn interface protocol may be an X2 interface protocol defined between base stations. In this case, the PDCP layer of one master base station is connected to both the RLC layer of the master base station and the RLC layer of the secondary base station. Here, the RLC layer of the master base station is called # 1 sub-entity, and the RLC layer of the secondary base station is called # 2 sub-entity. In the sub-entity, transmission and reception are divided into one-to-one matching. The sub-entity may be called an entity.

The RLC layer exists in a duplicate form. Each sub-entity is independent, but there are two sub-entities (# 1 sub-entity and # 2 sub-entity) in one RB (ie, # 1 RB). In this case, RLC parameters must be separately configured for the RLC-AM # 1 sub-entity and the RLC-AM # 2 sub-entity. Because the delay time that occurs when data serviced through each RLC-AM sub-entity is delivered to the terminal may be different from each other, the timer values to be set in consideration of the delay time may be different from each other. Because there is. If the delay time of data transmitted through each sub-entity is the same, the values of timers to be set for each sub-entity may be the same. This may be determined at the master base station or at the secondary base station, or at a network including the master base station and the secondary base station. Accordingly, data to be transmitted through the PDCP layer in the same RB may be transmitted through one of the RLC-AM # 1 sub-entity or the RLC-AM # 2 sub-entity. Here, an identifier for distinguishing through which sub-entities the data is transmitted may be further transmitted by the terminal receiving the data.

The example of FIG. 7 is also called a sub-entry RLC type, a separated RLC type, or an independent RLC type among the bearer split types. However, the example of FIG. 7 does not necessarily apply only to the bearer split.

8 is an exemplary diagram of subdividing another example of uplink transmission in a dual connection to which the present invention is applied at each layer level.

Referring to FIG. 8, for the same first RB (# 1 RB), the master base station includes the PDCP, RLC, MAC, and PHY layers, but the secondary base station includes the RLC, MAC, and PHY layers. The RLC layer of the master base station is connected to the RLC layer of the secondary base station using the Xn interface protocol. In this case, the RLC layer of the master base station is called a master RLC layer, and the RLC layer of the secondary base station is called a slave RLC layer.

In the case of downlink, additional segmentation is possible for the AMD / UM PDU of the slave RLC layer of the terminal. The segmentation operation of the slave RLC includes an operation of bundling a plurality of RLC PDUs or an operation of bundling the segmented AMD PDUs in the master RLC. In addition, it is possible to reconcatenate (concatenation) for the AMD / UM PDU of the slave RLC layer of the base station.

In the case of uplink, the small base station forwards it to the macro RLC layer when data is received through the slave RLC layer. Therefore, it does not matter whether the same data is received through the slave RLC layer or the master RLC layer through the MAC in the MeNB. Therefore, uplink transmission between the terminal and the base station is possible instead of TDM transmission.

Meanwhile, the MAC scheduler in each base station is mainly responsible for dynamic scheduling of radio resources. Since the situation of the MAC layer of the macro base station and the situation of the MAC layer of the small base station are different, the macro RLC layer allocates (or splits or connects or recombines) PDUs based on information provided by the MAC layer of the macro base station, and the slave RLC layer. Performs division or connection based on information provided by the MAC layer of the small base station.

In the uplink, there is only one RLC layer from the viewpoint of the terminal. In the downlink, because the MAC layer is divided into two or more base stations that are different from each other, and the difference in downlink radio conditions occurs for each base station, the RLC layer divides or recombines in different ways, whereas in the uplink, the secondary base station Since the slave RLC layer simply forwards the received data to the macro RLC layer, the only RLC layer that processes uplink data is the master RLC layer. Therefore, a dual connected terminal includes only one PDCP layer and RLC layer in a single RB for data to be transmitted to the two or more different base stations for uplink transmission. In addition, there may be only one MAC layer for controlling uplink transmission according to uplink resource allocation information received from two or more different base stations for uplink transmission. Therefore, from the viewpoint of uplink data transmission (for example, PUSCH), it is also possible to perform uplink transmission only to the master base station (this is also referred to as "single uplink").

The example of FIG. 8 is also called a master-slave RLC type among the bearer split types. However, the example of FIG. 8 does not necessarily apply only to the bearer split.

Hereinafter, uplink transmission during dual connection will be described in more detail.

The UE maps the uplink data generated in the application layer in the UE to the EPS bearer based on QoS. The uplink data is processed through the PDCP layer and the RLC layer in each RB mapped 1: 1 for each EPS bearer. The processed uplink data should be transmitted to a base station in which each RB is configured. That is, uplink data generated in each RB in the terminal should be transmitted to a base station in which an RB corresponding to the RB of the terminal is configured.

In the case of a non-double connection, since the terminal and the base station have a 1: 1 correspondence, uplink data of all RBs may be managed and multiplexed in the MAC layer as shown in FIG. 9. Also, as shown in FIG. 10, even when the MAC layer processes data based on uplink grants for each serving cell, a mapping relationship between each RB and a logical channel does not exist or exists.

Referring to FIG. 9, a terminal composed of a plurality of serving cells acquires an uplink grant that allocates uplink resources of each serving cell. The uplink grant is reported from the physical layer of the terminal to the MAC layer. In addition, the MAC layer of the terminal treats the uplink resources of the physical layer individually allocated for each serving cell as one aggregated (or aggregated) uplink resource set. In addition, the MAC layer of the UE may schedule or allocate data of the logical channel processed in each RB according to a logical channel priority (LCP) procedure. The LCP procedure is applied when performing a new transmission on the MAC. That is, it does not apply when retransmitting HARQ. For example, in the embodiment of FIG. 9, a first logical channel (channel 1), a second logical channel (channel 2), and a second logical channel (channel 3) are configured in a terminal, and a primary serving cell is configured. : PC), a first secondary serving cell (SC1), and a second secondary serving cell (SC2) are configured. In the MAC PDU, resources in which individual serving cells PC, SC1, and SC2 are integrated are allocated. And, according to the LCP procedure, since the priority of the first logical channel is 1, the portion corresponding to the prioritized bit rate (PBR) among uplink data in the first logical channel is the first MAC PDU. Maps to Then, the PBR portion of the second logical channel with priority 2, and then the PBR portion of the third logical channel with priority 3 are sequentially mapped to the MAC PDU.

Any MAC PDU consists of one MAC header, zero or more MAC SDUs, and zero or more MAC CEs and padding that can be optionally added.

The size of the MAC header and MAC SDUs are not uniform. One MAC PDU header is composed of one or more MAC PDU subheaders; Each subheader corresponds to MAC SDU, MAC CE or padding. The MAC PDU subheader consists of 6 header fields (R / R / E / LCID / F / L). However, the last subheader and the fixed size MAC CE are composed of four header fields (R / R / E / LCID). In the case of padding, the MAC PDU subheader corresponding to padding has four header fields (R / R / E / LCID) because it can always be located last in the MAC PDU.

MAC PDU subheaders have the same order as the corresponding MAC SDUs, MAC CEs and padding. That is, the first sub-header may correspond to padding when there is no first MAC SDU or MAC SDUs when there is no first MAC CE or MAC CE.

MAC CEs are always placed before MAC SDUs. Padding may occur at the end of the MAC PDU, except when 1-byte or 2-byte padding is required. Since the padding can be any value, the terminal should always be ignored. When padding is executed at the end of the MAC PDU, zero or more padding bytes are allowed. If one-byte or two-byte padding is required, one or two MAC PDU subheaders corresponding to the padding are positioned before other subheaders at the start position of the MAC PDU. Up to one MAC PDU may be transmitted for each transport block (TB) of each terminal. Up to one MCH MAC PDU may be transmitted for each TTI. Here, the MCH means a multicast channel.

Referring to FIG. 10, a terminal composed of a plurality of serving cells acquires an uplink grant that allocates uplink resources of each serving cell. In addition, the UE classifies (or individually) physical layer resources allocated to each serving cell. The UE allocates data of logical channels processed in each RB according to the LCP procedure based on each serving cell uplink resource. For example, in the embodiment of FIG. 10, a first logical channel (channel 1), a second logical channel (channel 2), and a second logical channel (channel 3) are configured in a terminal, and a primary serving cell (PCell) is provided. Suppose that the first secondary serving cell SCell1 is configured. The uplink resources of the primary serving cell and the first secondary serving cell are separated and allocated to MAC PDUs for each serving cell. When the LCP procedure is followed, a portion corresponding to the first logical channel PBR of the uplink data in the first logical channel having priority 1 is first mapped to the MAC PDU of the primary serving cell, and the second logical channel having priority 2 The portion of the uplink data corresponding to the second logical channel PBR is next mapped to the MAC PDU of the main serving cell. Since the uplink resource of the primary serving cell is limited, only a part of the PBR of the second logical channel is mapped to the MAC PDU. Next, the data mapped to the MAC PDU for the first secondary serving cell is a portion remaining after being mapped to the primary serving cell among uplink data in the first logical channel having priority number 1. At this time, only uplink resources of the first secondary serving cell are mapped.

On the other hand, in the case of dual connectivity, one RB in the terminal corresponds to multiple base stations. In other words, in the dual connection, one and the same RB (or EPS bearer) may be configured by two or more different base stations, and an uplink grant for a serving cell may also be configured by each base station. If the terminal configures the MAC PDU (s) as shown in FIG. 9 or 10 and transmits it to two or more base stations through a single RB, it is difficult for the two or more base stations to track their logical channel from the MAC PDU. This is because there is no definition of the mapping relationship between RB and logical channel.

Therefore, in a dual connection situation, a mapping relationship between an RB and a logical channel should be considered, and thus uplink scheduling is required. Hereinafter, in dual connectivity, configuration information (hereinafter, radio bearer configuration information) for mapping between RBs and logical channels is defined. The uplink transmission control in the dual connection according to the embodiments of FIGS. 5 to 8 may be enabled by the radio bearer configuration information defined as described above. And the terminal may be assigned scheduling parameters for optimizing data transmission for a single RB from each base station.

11 is a flowchart illustrating a method of transmitting uplink data in a heterogeneous network wireless communication system according to an example of the present invention. For convenience of description, it is assumed that a master base station (MeNB) and a secondary base station (SeNB) perform communication as a dual connection to the terminal. However, the technical idea of the present invention includes the case where there is more than one secondary base station.

Referring to FIG. 11, the master base station (MeNB) generates radio bearer configuration information for dual connectivity and transmits it to the terminal (S1100). Here, the radio bearer configuration information may be transmitted by the secondary base station, not the master base station. Radio bearer configuration information is RRC signaling, and can control scheduling of uplink data for each logical channel.

The terminal configures the same radio bearer (RB) corresponding to both the master base station and the secondary base station in the terminal based on the radio bearer configuration information (S1105). Here, the same radio bearer may be one or multiple. In step S1105, the same radio bearer is split or separated across multiple base stations to be configured in the terminal. As the same radio bearer, a portion separated by a terminal and a master base station is called a radio bearer on the master side, and a portion separated by a terminal and a secondary base station is called a radio bearer on the secondary side.

Step S1105 is an embodiment of a procedure for configuring a dual connection to a terminal. For example, in step S1105, the double connection is of any one of Figs. 6, different radio bearers are configured in the master base station and the secondary base station, respectively. 7 and 8, the same radio bearer in step S1105 corresponds to # 1 RB.

Since a plurality of base stations and a terminal are connected by the same radio bearer, the terminal can transmit uplink data to the base stations through the same radio bearer. In this regard, multiple logical channels may be mapped to the same radio bearer. In addition, a plurality of logical channels may not correspond to only one base station, but may correspond to a master base station and at least one secondary base station. The logical channel corresponding to the master base station is called a master logical channel, and the logical channel corresponding to the secondary base station is called a secondary logical channel. The primary logical channel is provided with data transmitted through a radio bearer on the master side (shortened 'data of the primary logical channel'). On the other hand, the data transmitted through the secondary side radio bearer (abbreviated as 'data of the secondary logical channel') is provided to the secondary logical channel.

The terminal performs uplink scheduling for transmitting data of the logical channel to the master base station and the secondary base station (S1110). Here, uplink scheduling may be referred to as an LCP procedure.

The terminal generates data of the main logical channel based on the LCP procedure and transmits it to the master base station (S1115). For transmission of uplink data of the primary logical channel, radio resources of the master base station (for example, a serving cell or primary serving cell in a Primary Timing Advance Group (pTAG)) are consumed. Here, the data of the main logical channel may be a MAC PDU or RLC PDU or PDCP PDU. In addition, pTAG is defined as a time alignment group including a main serving cell. In addition, the time alignment group is defined as a set of serving cells having the same time advance value and timing reference to each other. In addition, the time advance means that the base station instructs each terminal in the corresponding base station to transmit the uplink signal from a certain point in time based on the downlink reception point in the timing reference cell in order to receive the uplink signal of each terminal at a desired time point. The specific value indicated by the base station is called a time advance value. The time advance value may be set differently for each serving cell.

Then, the terminal generates data of the secondary logical channel based on the LCP procedure and transmits it to the secondary base station (S1120). For transmission of uplink data of the secondary logical channel, radio resources (eg, secondary serving cells) of the secondary base station are consumed. And steps S1115 and S1120 can be performed simultaneously.

Hereinafter, the radio bearer configuration information defined in step S1100 will be described in more detail.

As a first embodiment, the radio bearer configuration information controls the ID of a master logical channel corresponding to a master base station and multiplexing or assembling data of the primary logical channel into a MAC PDU. (master) Contains logical channel configuration information. Radio bearer configuration information according to the first embodiment may be defined as in Table 1 below.

DRB-ToAddMod :: = SEQUENCE { eps-BearerIdentity INTEGER (0..15) OPTIONAL,-Cond DRB-Setup drb-Identity DRB-Identity, pdcp-Config PDCP-Config OPTIONAL,-Cond PDCP rlc-Config RLC-Config OPTIONAL,-Cond Setup logicalChannelIdentity INTEGER (3..10) OPTIONAL,-Cond DRB-Setup logicalChannelConfig LogicalChannelConfig OPTIONAL,-Cond Setup ... }

Referring to Table 1, the radio bearer configuration information (DRB-ToAddMod) is an EPS bearer ID (den-BearerIdentity) field, a bearer ID (drb_Identity) field, a PDCP configuration (pdcp-Config) field, and an RLC configuration (rlc-Config) field. , Primary logical channel ID (logicalChannelIdentity) and primary logical channel configuration information (logicalChannelConfig). The main logical channel ID may be any integer from 3 to 10. The main logical channel configuration information can be defined, for example, as shown in Table 2 below.

-ASN1START LogicalChannelConfig :: = SEQUENCE { ul-SpecificParameters SEQUENCE { priority INTEGER (1..16), prioritisedBitRate ENUMERATED { kBps0, kBps8, kBps16, kBps32, kBps64, kBps128, kBps256, infinity, kBps512-v1020, kBps1024-v1020, kBps2048-v1020, spare5, spare4, spare3, spare2, spare1}, bucketSizeDuration ENUMERATED { ms50, ms100, ms150, ms300, ms500, ms1000, spare2, spare1}, logicalChannelGroup INTEGER (0..3) OPTIONAL-Need OR } OPTIONAL,-Cond UL ..., [[logicalChannelSR-Mask-r9 ENUMERATED {setup} OPTIONAL-Cond SRmask ]] } -ASN1STOP

Referring to Table 2, the main logical channel configuration information includes an uplink specific parameter (ul-SpecificParameters) field. The uplink specific parameter field includes, for example, a priority field indicating a priority in multiplexing or assembling data of a primary logical channel into a MAC PDU, a priority bit rate (PBR) field, and a bucket. Includes a bucket size duration (BSD) field. Since the uplink specific parameter field is included in the main logical channel configuration information, the priority field, the PBR field, and the BSD fields included in the uplink specific parameter field can all be considered to be included in the main logical channel configuration information.

The priority ranges from 1 to 16, and the larger the value, the lower the priority. The PBR field indicates a bit rate to be preferentially allocated when attempting to transmit data for a logical channel. The BSD field is a parameter for defining the bucket size. The priority and PRB of each logical channel may be set identically or differently.

As a second embodiment, the radio bearer configuration information may include the ID of the primary logical channel, the primary logical channel configuration information, and the secondary logical channel ID and secondary logical channel configuration information corresponding to the secondary base station. That is, in order to apply different LCP-related parameters for each base station, a parameter set constituting a logical channel may be newly added only for the secondary base station. Here, the sub logical channel configuration information is a set of parameters that control the multiplexing or assembling of the data of the sub logical channel into a MAC PDU.

DRB-ToAddMod :: = SEQUENCE { eps-BearerIdentity INTEGER (0..15) OPTIONAL,-Cond DRB-Setup drb-Identity DRB-Identity, pdcp-Config PDCP-Config OPTIONAL,-Cond PDCP pdcp-ConfigSeNB PDCP-Config OPTIONAL, --Cond BearerSplit-PDCP rlc-Config RLC-Config OPTIONAL,-Cond Setup rlc-ConfigSeNB RLC-Config OPTIONAL,-Cond BearerSplit-RLC rlc-ConfigSeNB RLC-Config OPTIONAL,-Cond BearerSplit-slaveRLC logicalChannelIdentity INTEGER (3..10) OPTIONAL,-Cond DRB-Setup logicalChannelConfig LogicalChannelConfig OPTIONAL,-Cond Setup logicalChannelIdentitySeNB INTEGER (3..10) OPTIONAL,-Need OR logicalChannelConfigSeNB LogicalChannelConfig OPTIONAL,-Need OR ... }

Referring to Table 3, the radio bearer configuration information according to the second embodiment includes all of the fields in Table 1, but further includes an ID (logicalChannelIdentitySeNB) and a secondary logical channel configuration information (logicalChannelConfigSeNB) of the secondary logical channel. This is a method of classifying and setting a structure for defining logical channel configuration information in the radio bearer configuration information of Table 1 for the master base station and the secondary base station. That is, as the secondary logical channel configuration information for the secondary base station is added, for example, it may be applied in the case of FIG. 7. Here, the configuration information for the PDCP and RLC entities in the UE corresponding to the PDCP and RLC entities in the SeNB is included depending on whether the bearer split method is an independent PDCP method (Cond BearerSplit-PDCP) or an independent RLC method (Cond BearerSplit-PDCP). Configuration information is different. In the case of the master / slave RLC scheme as shown in FIG. 8, configuration information for the RLC entity in the terminal corresponding to the slave RLC entity in the SeNB is included, and this is configuration information applied only when the terminal receives downlink. The auxiliary logical channel configuration information (LogicalChannelConfigSeNB) may be defined, for example, as shown in Table 4 below.

-ASN1START LogicalChannelConfigSeNB :: = SEQUENCE { ul-SpecificParameters SEQUENCE { priority INTEGER (1..16), prioritisedBitRate ENUMERATED { kBps0, kBps8, kBps16, kBps32, kBps64, kBps128, kBps256, infinity, kBps512-v1020, kBps1024-v1020, kBps2048-v1020, spare5, spare4, spare3, spare2, spare1}, bucketSizeDuration ENUMERATED { ms50, ms100, ms150, ms300, ms500, ms1000, spare2, spare1}, logicalChannelGroup INTEGER (0..3) OPTIONAL-Need OR } OPTIONAL,-Cond UL ... } -ASN1STOP

Referring to Table 4, the secondary logical channel configuration information includes an uplink specific parameter (ul-SpecificParameters) field. The uplink specific parameter field includes, for example, a priority field indicating a priority in multiplexing or assembling data of a secondary logical channel into a MAC PDU, a PBR field, and a BSD field. Compared to Table 2, unnecessary fields such as logicalChannelSR-Mask are omitted. Since the uplink specific parameter field is included in the secondary logical channel configuration information, the priority field, the PBR field, and the BSD fields included in the uplink specific parameter field can all be considered to be included in the sub logical channel configuration information. The priority ranges from 1 to 16, and the larger the value, the lower the priority. The PBR field indicates a bit rate to be preferentially allocated when attempting to transmit data for a logical channel. The BSD field is a parameter for defining the bucket size.

Upon receiving the radio bearer configuration information according to the second embodiment, the terminal performs the uplink scheduling of step S1110, that is, the LCP procedure in the uplink scheduling scheme as shown in FIG. 12.

12 is an explanatory diagram showing a method of performing uplink scheduling of a terminal according to an example of the present invention.

Referring to FIG. 12, the terminal performs communication based on a dual connection with a master base station and a secondary base station for uplink. As a radio bearer by dual connectivity, RB # 2 and RB # 3 are configured in the terminal, and RB # 1 is configured only between the master base station and the terminal. In particular, RB # 2 and RB # 3 are divided into a master side RB and a secondary side RB by bearer split, respectively.

From the viewpoint of uplink scheduling, logical channels 1, 2, and 3 (channels 1, 2, 3) correspond to the master base station, and logical channels 4, 5 (channels 4, 5) correspond to the secondary base station. Logical channel 1 is mapped to RB # 1. And logical channel 2 (master base station) and logical channel 5 (secondary base station) are mapped to the same RB # 2 by a bearer split. Similarly, logical channel 3 (master base station) and logical channel 4 (secondary base station) are mapped to the same RB # 3 by a bearer split. That is, a single RB is assigned to different logical channels LC.

The UE independently performs the LCP procedure for each logical channel mapped to each base station in consideration of available resources provided by serving cells configured with each logical channel and each uplink. For example, the terminal configures a first MAC PDU (1st MAC PDU) based on priority of each logical channel, PBR, and logical channel configuration information such as BSD. Since the priority of logical channel 1 is number 1, PBR among all data of logical channel 1 is first allocated to the first MAC PDU. Next, since the priority of logical channel 2 is 2, PBR of all data of logical channel 1 is allocated to the first MAC PDU. In addition, the UE may transmit the first MAC PDU by using available resources provided by the primary serving cell (PCell: PC) and the first secondary serving cell (SCell1: SC1) configured in the master base station.

Similarly, the terminal configures a second MAC PDU (2nd MAC PDU) based on the priority of each logical channel, PBR, and logical channel configuration information such as BSD. Since the priority of logical channel 4 is 1, PBR among all data of logical channel 4 is first allocated to the second MAC PDU. Next, since the priority of logical channel 5 is 2, PBR among all data of logical channel 5 is allocated to the second MAC PDU. In addition, the terminal may transmit the second MAC PDU by using the resources provided by the second secondary serving cell SC2 and the third secondary serving cell SC3 configured in the secondary base station.

Such an uplink scheduling scheme can be usefully used in a radio protocol architecture in which RLC is independently operated, such as independent RLC.

Here, FIG. 12 is exemplified as generating MAC PDUs using a resource given by an uplink grant of serving cells in each base station as one integrated resource as shown in FIG. 9. However, the UE may generate MAC PDU by independently uplink scheduling for each uplink grant for the serving cell in each base station as shown in FIG. 10. In this case, the UE generates a third MAC PDU and a fourth MAC PDU to be assigned to the PC and SC1, respectively, with respect to the master base station, and a fifth MAC PDU and a sixth MAC PDU to be assigned to SC2 and SC3, respectively, to the secondary base station. To create.

Here, a MAC control element (CE) to be transmitted for each base station may be independently generated and included in the MAC PDU. If a specific MAC CE needs to be transmitted to a specific base station, the MAC PDU to be transmitted to the corresponding base station is included and transmitted.

As a third embodiment of the radio bearer configuration information in step S1100, the radio bearer configuration information may include the ID of the primary logical channel, the primary logical channel configuration information, and secondary logical channel configuration information about the secondary base station. Radio bearer configuration information according to the third embodiment may be defined as shown in Table 5 below.

DRB-ToAddMod :: = SEQUENCE { eps-BearerIdentity INTEGER (0..15) OPTIONAL,-Cond DRB-Setup drb-Identity DRB-Identity, pdcp-Config PDCP-Config OPTIONAL,-Cond PDCP pdcp-ConfigSeNB PDCP-Config OPTIONAL, --Cond BearerSplit-PDCP rlc-Config RLC-Config OPTIONAL,-Cond Setup pdcp-ConfigSeNB PDCP-Config OPTIONAL, --Cond BearerSplit-PDCP rlc-ConfigSeNB RLC-Config OPTIONAL, --Cond BearerSplit-slaveRLC logicalChannelIdentity INTEGER (3..10) OPTIONAL,-Cond DRB-Setup logicalChannelConfig LogicalChannelConfig OPTIONAL,-Cond Setup logicalChannelConfigSeNB LogicalChannelConfig OPTIONAL,-Need OR ... }

Referring to Table 5, the radio bearer configuration information according to the third embodiment includes all the fields in Table 1, but further includes sub-logical channel configuration information (logicalChannelConfigSeNB). This is a method of classifying and setting a structure for defining logical channel configuration information in the radio bearer configuration information of Table 1 for the master base station and the secondary base station. That is, secondary logical channel configuration information for the secondary base station is added. However, the radio bearer configuration information according to the third embodiment does not include the ID of the secondary logical channel, unlike the second embodiment.

Upon receiving the radio bearer configuration information according to the third embodiment, the terminal performs the uplink scheduling of step S1110, that is, the LCP procedure in the uplink scheduling scheme as shown in FIG. 13.

13 is an explanatory diagram showing a method of performing uplink scheduling of a terminal according to another example of the present invention.

Referring to FIG. 13, the terminal performs communication based on a dual connection with a master base station and a secondary base station for uplink. As a radio bearer by dual connectivity, RB # 2 and RB # 3 are configured in the terminal, and RB # 1 is configured only between the master base station and the terminal. In particular, RB # 2 and RB # 3 are divided into a master side RB and a secondary side RB by bearer split, respectively.

From the viewpoint of uplink scheduling, logical channels 1, 2, and 3 (channels 1, 2, 3) correspond to the master base station, and logical channels 2, 3 (channels 2, 3) correspond to the secondary base station. Logical channel 2 is mapped to RB # 2 on the master side and RB # 2 on the secondary side, and logical channel 3 is mapped to RB # 3 on the master side and RB # 3 on the secondary side.

According to this, a single RB is allocated to the same logical channel by the bearer split, but the UE can perform a LCP procedure by defining a bucket for classifying the logical channel configured as described above for each base station.

A distinctive feature of the embodiment of FIG. 13 is that the terminal should consider the amount of data to be transmitted to each base station for the same logical channel. For example, the terminal should distinguish the amount of data to be transmitted to each base station for the same logical channel, and provide the RLC entity for each base station with the transmission opportunity and the total RLC PDU size according to the distinguished data amount. This is a request for the distinguished RLC layer in which the MAC layer of the terminal is located above the MAC layer.

To implement this, the terminal must store data in the same logical channel separately in different virtual spaces, that is, buckets. In Table 5, the secondary logical channel configuration information is included in the radio bearer configuration information to define a bucket according to the present embodiment. Different priority, PBR, and BSD logical channel parameters may be set for different buckets in the same logical channel, and may include one or more of them.

When the embodiment of FIG. 13 is applied to steps S1115 and S1120 of FIG. 11, the data of the primary logical channel becomes data of bucket 1, and the data of the secondary logical channel is data of bucket 2 Becomes This is because the terminal operates different buckets for the same logical channel. For example, the UE stores data of logical channel 2 mapped to RB # 2 in a first bucket (bucket 1) for the master base station and a second bucket (bucket 2) for the secondary base station.

In addition, the terminal independently configures the MAC PDU_m and MAC PDU_s by independently performing the LCP procedure for each bucket for data stored in buckets 1 and 2. The UE first configures the MAC PDU from the data to be transmitted through the master base station according to the existing LCP procedure. Here, PBR (B1) means PBR applied to bucket 1. Next, the terminal is configured as a MAC PDU according to the LCP procedure from data to be transmitted through the secondary base station among data remaining in each logical channel capable of bearer splitting.

In addition, the terminal transmits MAC PDU_m and MAC PDU_s to the master base station and the secondary base station, respectively, using available resources provided by each base station (for example, a serving cell configured with uplink).

Unlike the uplink scheduling of FIG. 13, the UE may perform uplink scheduling in the same manner as in FIG. 14 based on radio bearer configuration information according to the third embodiment.

14 is an explanatory diagram showing a method of performing uplink scheduling of a terminal according to another example of the present invention.

Referring to FIG. 14, a single RB is allocated to the same logical channel as shown in FIG. 13, but does not define separate virtual spaces such as buckets. In this case, the terminal classifies available resources for each base station based on priority and performs LCP procedures.

The characteristic of the embodiment of FIG. 14 different from the embodiment of FIG. 13 is that the RLC entity for uplink transmission can be configured as one. That is, when the UE provides the transmission opportunity and the total RLC PDU size to the separated RLC layer existing above the MAC layer, it can provide a single information to the RLC layer for each logical channel as before.

In this case, the terminal sequentially performs the LCP procedure for each logical channel mapped to each base station in consideration of available resources provided by serving cells configured with each logical channel and each uplink. That is, the terminal first configures the first MAC PDU from data to be transmitted through the master base station according to the existing LCP procedure. Next, the terminal is configured as a MAC PDU according to the LCP procedure from data to be transmitted through the secondary base station among data remaining in each logical channel capable of bearer splitting.

11, the LCP procedure in steps S1115 and S1120 will be described in more detail as follows.

In performing the LCP procedure, the terminal must maintain the variable Bj for each logical channel j. Bj is initialized to 0 when the logical channel j is initially set, and is increased by PBR × TTI for each TTI. However, the Bj value cannot exceed the bucket size, and if the Bj value is larger than the bucket size value, the Bj value should be set as the bucket size value. The bucket size is equal to PBR × BSD.

The terminal must execute the LCP procedure when a new transmission is performed. The terminal does not transmit data on the logical channel corresponding to the reserved radio bearer, and allocates resources to the logical channels through the following steps.

(1) The terminal allocates resources for all logical channels having a Bj value greater than 0 in descending order of priority. If the PBR value of any radio bearer is set to infinity, the terminal allocates resources for all data that can be transmitted from the radio bearer.

(2) The terminal decreases the Bj value. The reduction value is the total size of MAC SDUs provided in the logical channel in (1). Here, the Bj value may be negative.

(3) If resources remain, the UE allocates the resources to all logical channels in order of high priority until the data or uplink grant for the logical channel is exhausted regardless of all Bj values. If logical channels having the same priority are present, the same goes to the logical channels.

When the UE is required to transmit multiple MAC PDUs within a single TTI, the LCP procedures (1) to (3) and other related procedures related thereto may be independently applied to each uplink grant. Or, it may be applied to the sum of capacities of uplink grants. In addition, which uplink grants are to be performed in the order depends on the implementation of the terminal. In addition, in such a case, it is also dependent on the implementation of the terminal to determine which MAC PDU to include MAC CE.

The UE may comply with the following rules during the LCP procedure of (1) to (3). i) If the entire SDU (or partially transmitted SDU or retransmitted RLC PDU) fits the remaining resources, the UE does not subdivide any RLC SDU (or partially transmitted SDU or retransmitted RLC PDU). ii) If the UE has segmented any RLC SDU from the logical channel, the size of the segment for filling the uplink grant is maximized as much as possible. iii) The terminal maximizes data transmission. iv) If the size of a given uplink grant is greater than or equal to 4 bytes while the UE has transmittable data, the UE does not transmit only padding BSR and / or padding (however, the size of the uplink grant) Is less than 7 bytes and the AMD PDU segment does not need to be transmitted).

Meanwhile, in performing the LCP procedure, the UE should consider priorities in the order shown in the following table.

Priority Data or MAC CE One Data from MAC CE or UL-CCCH for C-RNTI 2 MAC CE for BSR, except for BSR included for padding 3 MAC CE for PHR or Extended PHR 4 Data from logical channels, except data from UL-CCCH 5 MAC CE for BSR included for padding

11 to 14, when configuring the MAC PDU based on the LCP procedure, it is basically assumed that the master base station has a higher priority than the secondary base station. So, the data of the primary logical channel is allocated to the MAC PDU by being allocated resources in a priority order, and the data of the secondary logical channel is mapped to the MAC PDU by receiving the remaining resources. However, this is only an example and the priority of the secondary base station may be higher than that of the master base station, and the priority between these base stations may be determined in various ways. As an example, the base station determines the priority between base stations, and may transmit information on the determined priority to the terminal by RRC signaling. As another example, a priority of a base station including a primary serving cell may be determined higher than that of a base station that does not. As another example, the priority of a base station having many available resources may be determined to be higher than that of a base station that does not. As another example, among specific MAC CEs to be transmitted in a corresponding TTI, a priority of a base station to transmit a high priority MAC CE (compared to a priority of data of a logical channel) may be determined to be higher than a base station that does not.

In step S1120 of FIG. 11, the secondary base station receiving the data of the secondary logical channel provides the data of the secondary logical channel to the PCDP layer of the master base station through the Xn interface in the RLC layer of the secondary base station according to the path as shown in FIG. 7. can do. Alternatively, the secondary base station that has received the data of the secondary logical channel may simply forward the data of the secondary logical channel from the RLC layer of the secondary base station to the RLC layer of the master base station along the path as shown in FIG. 8. That is, in the master-slave RLC configuration of FIG. 8, the secondary base station receiving the uplink data simply delivers all the received data to the RLC layer in the master base station regardless of whether the RLC PDU is configured. Therefore, the RLC layer of the master base station can configure RLC PDUs by combining data transmitted from MAC layers in different base stations.

When a terminal configures MAC PDU (s) according to an embodiment of the present invention, a mapping relationship between uplink grants for serving cells configured for each base station and an RB configured for each base station and a corresponding logical channel is considered. You can. And the terminal can support QoS for each base station through uplink by performing uplink scheduling based on the mapping relationship.

15 is a block diagram of a terminal and a base station according to an example of the present invention.

15, the terminal 1500 includes a receiving unit 1505, a UE processor 1510 and a transmitting unit 1515. The UE processor 1510 is composed of a radio bearer setting unit 1511 and a data processing unit 1512 again.

The reception unit 1505 receives radio bearer configuration information from the MeNB 1550. The radio bearer configuration information may be defined by any one of radio bearer configuration information according to the first embodiment, the second embodiment, and the third embodiment disclosed herein.

The radio bearer setting unit 1511 configures the terminal 1500 with the same radio bearer (RB) corresponding to both the MeNB 1550 and the SeNB 1580 based on radio bearer configuration information. Here, the same radio bearer may be one or multiple. The same radio bearer is split or separated across the MeNB 1550 and the SeNB 1580 to be configured in the terminal 1500. As the same radio bearer, the part separated by the terminal 1500 and the MeNB 1550 is called the RB of the master side, and the part separated by the terminal 1500 and the SeNB 1580 is called the RB of the secondary side. For example, the dual connection may be of any one of FIGS. 6 to 8. 6, different radio bearers are configured in the master base station and the secondary base station, respectively. 7 and 8, the same radio bearer corresponds to # 1 RB.

The data processor 1512 performs uplink scheduling for transmitting data of the logical channel to the MeNB 1550 and SeNB 1580. Here, uplink scheduling may be referred to as an LCP procedure. The data processing unit 1512 generates data of the primary logical channel and data of the secondary logical channel based on the LCP procedure. At this time, the data processing unit 1512 may generate a MAC PDU based on the scheme proposed in FIGS. 12 to 14.

The transmission unit 1515 transmits data generated by the data processing unit 1512 to the MeNB 1550 and the SeNB 1580, respectively. In this case, the data transmitted to the MeNB 1550 may be data mapped to the primary logical channel as the first MAC PDU, and the data transmitted to the SeNB 1580 may be data mapped to the secondary logical channel as the second MAC PDU. . Meanwhile, the transmission unit 1515 transmits data of the primary logical channel on the first serving cell using the uplink resource provided by the uplink grant of the MeNB 1550, and transmits the data of the secondary logical channel to the SeNB 1580. It may be transmitted on the second serving cell by using the uplink resource provided by the uplink grant of.

The MeNB 1550 includes a transmitter 1555, a receiver 1565, and a MeNB processor 1560. The MeNB processor 1560 is composed of a message generation unit 1562 and a parameter determination unit 1561 again.

The parameter determination unit 1561 determines parameters required for radio bearer configuration and logical channel configuration. For example, the parameter determination unit 1561 determines all parameters defined in Tables 1 to 6. In addition, the parameter determining unit 1561 may determine priority between base stations in mapping logical channel data to MAC PDUs.

The message generation unit 1562 generates radio bearer configuration information including the determined parameter and sends it to the transmission unit 1555.

The transmitting unit 1555 transmits radio bearer configuration information to the terminal 1500.

The receiving unit 1565 receives main logical channel data transmitted from the terminal 1500. Also, the receiving unit 1565 may receive data provided from the RLC layer of the SeNB 1580 to the PDCP layer of the MeNB 1550. Also, the receiving unit 1565 may receive data transmitted from the RLC layer of the SeNB 1580 to the RLC layer of the MeNB 1550.

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

The above-described embodiments include examples of various aspects. It is not possible to describe all possible combinations for representing various aspects, but a person skilled in the art will recognize that other combinations are possible. Accordingly, the present invention will be said to include all other replacements, modifications and changes that fall within the scope of the following claims.

Claims (12)

In a wireless communication system, a method in which a user equipment transmits uplink data to a master base station (master eNodeB: MeNB) and at least one secondary base station (SeNB),
Receiving radio bearer configuration information for dual connectivity from the master base station;
Based on the radio bearer configuration information, configuring the same radio bearer corresponding to both the master base station and the at least one secondary base station in the terminal;
Transmitting data of a master logical channel (LC) mapped to the same radio bearer to the master base station; And
And transmitting data of a secondary logical channel mapped to the same radio bearer to the at least one secondary base station. According to claim 1, The radio bearer configuration information,
Main logical channel configuration information indicating priority in multiplexing or assembling the data of the primary logical channel into a medium access control (MAC) protocol data unit (PDU);
Method for transmitting uplink data, including the ID of the primary logical channel. delete delete delete delete In a terminal for transmitting uplink data to a master base station (master eNodeB: MeNB) and at least one secondary eNB (SeNB) in a wireless communication system,
A receiver configured to receive radio bearer configuration information for dual connectivity from the master base station;
A radio bearer setting unit configured to configure the same radio bearer corresponding to both the master base station and the at least one secondary base station in the terminal based on the radio bearer configuration information;
A data generating unit generating data of a master logical channel (LC) mapped to the same radio bearer and generating data of a secondary logical channel mapped to the same radio bearer; And
A terminal comprising a transmitter for transmitting data of the primary logical channel to the master base station, and transmitting data of the secondary logical channel to the at least one secondary base station. The method of claim 7, wherein the radio bearer configuration information,
Main logical channel configuration information indicating priority in multiplexing or assembling the data of the primary logical channel into a medium access control (MAC) protocol data unit (PDU);
The terminal comprising the ID of the primary logical channel. delete delete delete delete

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