KR20140073377A

KR20140073377A - Method and apparatus of controloing extension bearer in heterogeneous network wireless communication system

Info

Publication number: KR20140073377A
Application number: KR1020130005334A
Authority: KR
Inventors: 권기범; 허강석; 안재현
Original assignee: 주식회사 팬택
Priority date: 2012-12-06
Filing date: 2013-01-17
Publication date: 2014-06-16

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for controlling an Extension Bearer in a heterogeneous network wireless communication system. For this purpose, the macro base station of the present invention receives a measurement report from a terminal and, based on the measurement report, transmits, to the macro cell, a small cell using a frequency different from the frequency used by the macrocell, And transmits the RLC extension request message to the small base station in response to the RLC extension request message by generating an RLC extension response message to the small cell of the small base station, Small base station. The macro base station forwards the data to be transmitted to the mobile station to the small base station, and the small base station can transmit data to the mobile station through the extended bearer. According to the present invention, a macro base station can distribute a load requiring an excessive load or a specific QoS to a small cell, and a terminal can smoothly receive a data service.

Description

Technical Field [0001] The present invention relates to an extended bearer control method and apparatus for a heterogeneous network wireless communication system,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to wireless communication, and more particularly, to a method and apparatus for controlling an Extension Bearer in a heterogeneous network wireless communication system.

A multiple component carrier system refers to a wireless communication system capable of supporting carrier aggregation. 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 use a logically large band So as to achieve the same effect as the above. Multi-element carrier systems support multiple component carriers (CCs) that are distinct in the frequency domain. The element carrier includes an uplink element carrier used in the uplink and a downlink element carrier used in the downlink. A DL serving as a serving cell may be formed by combining a downlink component carrier and an uplink component carrier. Or one serving cell may be composed of only the downlink component carrier.

In certain areas, such as a hotspot inside a cell, there is a particularly high demand for communication, and in certain areas, such as the cell edge or coverage hole, the reception sensitivity of the radio wave may be reduced. 2. Description of the Related Art As wireless communication technology has developed, small cells in a macro cell, for example, a pico cell, have been used for the purpose of enabling communication in an area such as a hot spot, a cell boundary, A pico cell, a femtocell, a micro cell, a remote radio head (RRH), a relay, and a repeater are installed together. Such a network is called a heterogeneous network (HetNet). In a heterogeneous network environment, a macro cell is a large cell with a large coverage and a small cell such as a femtocell and a picocell is a small cell. In a heterogeneous network environment, coverage overlap occurs between a plurality of macro cells and small cells.

A terminal connected to a network can perform communication with an arbitrary cell according to a channel environment or a moving state, and can perform a cell change. In case of cell change, a handover can be performed to solve a problem of call drop occurring when moving to an adjacent cell. Handover refers to a process of moving from a current communication service area (hereinafter, referred to as a source cell) to a neighboring communication service area (hereinafter, referred to as a target cell) traffic channel to maintain a constant call state. That is, a terminal communicating with a specific base station is linked to another adjacent base station (hereinafter referred to as a target base station) when the signal strength at the specific base station (hereinafter referred to as a source base station) becomes weak . For example, a terminal may disconnect from a macro cell and connect to another macro cell or picocell due to deterioration of a channel state in a state of being connected to a macro cell. Or, as the terminal moves while connected to the macro cell, it can disconnect from the macro cell and connect to another macro cell or picocell.

A terminal may perform wireless communication through any one of base stations constituting at least one serving cell. In a heterogeneous network environment, a mobile station having a connection with a base station constituting a macro cell has good signal quality of other base stations constituting a small cell, and even when a radio resource utilization rate is low, . Also, even if a terminal is connected to a base station constituting a small cell through a handover procedure or the like, the coverage of the small cell is relatively small, so that handover frequently occurs according to the movement of the terminal. This is true even if the terminal supports multi-element carriers. Accordingly, there is a need for a cell planning method for distributing load, which requires an excessive load or a specific QoS (Quality of Service) in a heterogeneous network environment, to a small cell without a handover procedure and efficiently transmitting data.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and apparatus for setting up and operating an extended bearer in a wireless communication system.

Another object of the present invention is to provide a cell planning method for efficiently transmitting data to a mobile station without causing an unnecessary load on the cell in a heterogeneous network environment.

Another aspect of the present invention is to efficiently transmit data to a terminal through expansion of a radio bearer (RB).

Another aspect of the present invention is to simultaneously provide services to a terminal through macro cells and small cells using different frequencies.

Another aspect of the present invention is to provide specific data to a terminal connected to a macro cell through a small cell.

Another aspect of the present invention is to provide a service through a small cell suitable for service operation of a specific QoS (Quality of Service).

Another technical object of the present invention is to prevent frequent handover of a terminal and seamlessly provide data.

According to an aspect of the present invention, there is provided a macro base station (macro eNB) supporting an extension bearer setup in a heterogeneous network system. The macro base station includes a macro radio receiving unit for receiving a measurement report from a terminal, a wireless base station for transmitting a measurement report to a small cell using a frequency different from a frequency used by a macro cell, A macro processor for generating an RLC extension request message for requesting an extended bearer setup based on a link control (RLC) step, a macro wired transmission unit for transmitting the RLC extension request message to a small eNB, And a macro wired receiver for receiving, in response to the RLC extension request message, an RLC extension response message to the small cell of the small base station, the RLC extension response message indicating whether to accept the extended bearer setup.

According to another aspect of the present invention, there is provided a small base station supporting an extended bearer setup in a heterogeneous network system. Wherein the small base station comprises: a small wired receiver for receiving an RLC extension request message for requesting a small cell from the macro base station for setting up an extended bearer on the basis of an RLC layer; an RLC extension requesting unit for, based on the RLC extension request message, A small processor for generating an extended response message, and a small wired transmission unit for transmitting the RLC extended response message to the macro base station.

According to another aspect of the present invention, there is provided a method for transmitting / receiving data through an extended bearer in a heterogeneous network system. The method includes: performing a measurement report to a macro base station; receiving at least one of parameters for RLC sub-stages of the small cell, DRB configuration information for the extended bearer, and secondary cell configuration information for the small cell from the macro base station Receiving a RRC connection reconfiguration message including a RRC connection reconfiguration message, configuring DRB setup and the small cell as a serving cell, and configuring / reconfiguring an RLC sub-stage of the UE, And receiving the downlink data from the small base station through the small cell configured as the secondary serving cell.

According to another aspect of the present invention, a method is provided in which a macro base station supports an extended bearer setup in a heterogeneous network system. The method includes receiving a measurement report from a UE, generating an RLC Extension Request message for requesting an establishment of an E-DCH based on the RLC layer for a small cell based on the measurement report, And receiving, in response to the RLC extension request message, an RLC extension response message to the small cell of the small base station, the RLC extension response message indicating whether to accept the extended bearer setup from the small base station. do.

According to another aspect of the present invention, a method is provided in which a small base station supports an extended bearer setup in a heterogeneous network system. The method includes receiving an RLC Extension Request message requesting an MBS based on an RLC layer for a small cell from a macro base station, determining an extended bearer setup based on the RLC Extension Request message, Configuring / reconfiguring the RLC extension response message, generating an RLC extended response message including parameters for the configured / reconfigured RLC sub-step, and transmitting the RLC extended response message to the macro base station.

According to the present invention, when it is difficult for a macro base station to provide a service satisfying a specific QoS among the services requested by a terminal connected to a macro cell, a service satisfying the QoS can be provided to a small base station (for example, a femto base station, Etc.) to the terminal.

According to the present invention, when the macro base station determines that it is necessary to control the load level in the macro cell based on the load management policy or the like, the service satisfying the specific QoS can be provided to the terminal through the small cell of the small base station.

According to the present invention, it is possible to provide a QoS adaptive service by preventing frequent handover of a terminal and by allocating a small cell as a secondary serving cell to distribute the load of the macro cell to the small cell.

According to the present invention, in the uplink transmission of the MS, the macro base station or the MS sets the secondary serving cell as the uplink transmission path for the uplink data related to the service receiving the data through the secondary serving cell, The UE can transmit the uplink data through the small cell.

1 shows a wireless communication system to which the present invention is applied.
2 is a block diagram illustrating a radio protocol architecture for a user plane.
3 is a block diagram illustrating a wireless protocol structure for a control plane.
FIG. 4 shows a structure of a bearer service in a wireless communication system to which the present invention is applied.
5 is a diagram schematically illustrating a concept of a heterogeneous network composed of a macro base station, a femto base station, and a pico base station according to the present invention.
6 shows an example of the arrangement of terminals and base stations in a heterogeneous network system.
7 shows a signaling procedure of a macro base station and a small base station for setting up an extended bearer according to the present invention.
8 is a conceptual diagram showing a connection configuration between a macro base station and a small base station according to the present invention.
9 is a flowchart illustrating signaling between a terminal, a macro base station, and a small base station according to an exemplary embodiment of the present invention.
10 is a flowchart illustrating an operation of a macro base station in a bearer extension procedure according to an exemplary embodiment of the present invention.
11 is a flowchart illustrating operations of a small base station in a bearer extension procedure according to an exemplary embodiment of the present invention.
12 is a flowchart illustrating an operation of a UE in a bearer extension procedure according to an exemplary embodiment of the present invention.
13 is a flowchart illustrating signaling between a terminal, a macro base station, and a small base station according to another example of the present invention.
FIG. 14 is a flowchart illustrating the operation of the macro base station in the bearer extension procedure according to another example of the present invention.
15 is a flowchart showing the operation of the small base station in the bearer extension procedure according to another example of the present invention.
16 is a flowchart illustrating an operation of a UE in a bearer extension procedure according to another example of the present invention.
17 is a block diagram of a terminal, a macro base station, and a small base station 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 shows a wireless communication system to which the present invention is applied. This may be a network structure of an Evolved-Universal Mobile Telecommunications System (E-UMTS). The E-UMTS system may be called LTE (Long Term Evolution) or LTE-A (advanced) system. Wireless communication systems are widely deployed to provide various communication services such as voice, packet data, and the like.

On the other hand, there is no limitation on a multiple access technique applied to a wireless communication system. (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier-FDMA , OFDM-CDMA, and the like.

Here, TDD (Time Division Duplex) scheme in which uplink and downlink transmission are transmitted using different time periods or FDD (Frequency Division Duplex) scheme in which they are transmitted using different frequencies may be used .

Referring to FIG. 1, an E-UTRAN includes a base station (BS) 20 that provides a control plane and a user plane to a user equipment (UE) 10. 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) .

The base station 20 generally refers to a station that communicates with the terminal 10 and includes an evolved NodeB (eNodeB), a Base Transceiver System (BTS), an access point, a femto-eNB, A pico-eNB, a home eNB, a relay, and so forth. The base station 20 may provide at least one cell to the terminal. The cell may mean a geographical area where the base station 20 provides communication services, or may refer to a specific frequency band. A cell may denote a downlink frequency resource and an uplink frequency resource. Or a cell may mean a combination of a downlink frequency resource and an optional uplink frequency resource.

The base stations 20 may be interconnected via an X2 interface. The base station 20 is connected to an S-GW (Serving Gateway) through an MME (Mobility Management Entity) and an S1-U through an EPC (Evolved Packet Core) 30, more specifically, an S1-MME through an S1 interface. The S1 interface exchanges OAM (Operation and Management) information to support the movement of the terminal 10 by exchanging signals with the MME.

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, (Internet Protocol).

The wireless interface between the terminal and the base station is called a Uu interface. The layers of the radio interface protocol between the UE and the network are classified into L1 (first layer), L1 (second layer), and the like based on the lower three layers of the Open System Interconnection (OSI) A physical layer belonging to a first layer provides an information transfer service using a physical channel, and a physical layer (physical layer) An RRC (Radio Resource Control) layer located at Layer 3 controls the radio resources between the UE and the network. To this end, the RRC layer exchanges RRC messages between the UE and the BS.

2 is a block diagram illustrating a radio protocol architecture for a user plane. 3 is a block diagram illustrating a wireless 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.

2 and 3, a physical layer (PHY) provides an information transfer service to an upper layer using a physical channel. The physical layer is connected to a medium access control (MAC) layer, which is an upper layer, through a transport channel. Data is transferred between the MAC layer and the physical layer through the transport channel. The transport channel is classified according to how the data is transmitted through the air interface. Data is transferred between the different physical layers, that is, between the transmitter and the physical layer of the receiver through a physical channel. The physical channel can be modulated by an Orthogonal Frequency Division Multiplexing (OFDM) scheme, and uses time and frequency as radio resources. There are several physical control channels. The physical downlink control channel (PDCCH) informs the UE of resource allocation of a paging channel (PCH), a downlink shared channel (DL-SCH), and hybrid automatic repeat request (HARQ) information related to the DL-SCH. The PDCCH may carry an uplink scheduling grant informing the UE of the resource allocation of the uplink transmission. A physical control format indicator channel (PCFICH) informs the UE of the number of OFDM symbols used for PDCCHs and is transmitted every subframe. PHICH (Physical Hybrid ARQ Indicator Channel) carries HARQ ACK / NAK signal in response to uplink transmission. A physical uplink control channel (PUCCH) carries uplink control information such as HARQ ACK / NAK, scheduling request and CQI for downlink transmission. A physical uplink shared channel (PUSCH) carries an uplink shared channel (UL-SCH).

The function of the MAC layer includes a mapping between a logical channel and a transport channel and a multiplexing / demultiplexing into a transport block provided as a physical channel on a transport channel of a MAC SDU (service data unit) belonging to a 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 transferring control area information and a traffic channel for transferring user area information.

The function of the RLC layer includes concatenation, segmentation and reassembly of the RLC SDUs. In order to guarantee various QoS (Quality of Service) required by a radio bearer (RB), the RLC layer includes Transparent Mode (TM), Unacknowledged Mode (UM), and Acknowledged Mode , And AM). AM RLC provides error correction via automatic repeat request (ARQ).

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

The RRC layer is responsible for the control of logical channels, transport channels and physical channels in connection with the configuration, re-configuration and release of RBs. RB means 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. The RB may be further classified into an SRB (Signaling RB) and a DRB (Data RB). The SRB is used as a path for transmitting the RRC message and the NAS 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.

The downlink transmission channel for transmitting data from the network to the terminal includes a BCH (Broadcast Channel) for transmitting system information and a downlink SCH (Shared Channel) for transmitting user traffic or control messages. In case of a traffic or control message of a downlink multicast or broadcast service, it may be transmitted through a downlink SCH, or may be transmitted via a separate downlink MCH (Multicast Channel). Meanwhile, the uplink transmission channel for transmitting data from the UE to the network includes a random access channel (RACH) for transmitting an initial control message and an uplink SCH (Shared Channel) for transmitting user traffic or control messages.

A logical channel mapped to a transport channel is a broadcast control channel (BCCH), a paging control channel (PCCH), a common control channel (CCCH), a multicast control channel (MCCH), a multicast traffic Channel).

A physical channel is composed of a plurality of subcarriers in a frequency domain and a plurality of symbols in a time domain. One sub-frame is composed of a plurality of OFDM symbols in the time domain. One subframe is composed of a plurality of resource blocks, and one resource block is composed of a plurality of symbols and a plurality of subcarriers. Also, each subframe may use specific subcarriers of the specific symbols (e.g., the first symbol) of the corresponding subframe for PDCCH (Physical Downlink Control Channel). The transmission time interval (TTI), which is the unit time at which data is transmitted, is 1 ms corresponding to one subframe.

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

Referring to FIG. 4, the RB is a bearer provided in the Uu interface to support the service of the user. In the wireless communication system, each bearer is defined for each interface to ensure independence between interfaces.

The bearer provided by the wireless communication system is collectively referred to as an evolved packet system (EPS) bearer. The EPS bearer is a transmission path generated between the terminal and the P-GW. The P-GW may receive an IP flow from the Internet or may transmit an IP flow over the Internet. The E-RAB can be divided into RB (Radio Bearer), S1 (Bearer), and E-RAB (Bearer). The EPS bearer can be divided into E-RAB (E-UTRAN Radio Access Bearer) It can be divided into bearers. That is, one EPS bearer corresponds to one RB, S1 bearer, and S5 / S8 bearer, respectively. Depending on which service (or application) is used, the IP flow may have different QoS (Quality of Service) characteristics, and IP flows having different QoS characteristics may be mapped and transmitted for each EPS bearer. EPS bearer can be distinguished based on EPS bearer identity. The EPS Bearer Identifier is allocated by the UE or the MME.

EPS bearer types have a default bearer and a dedicated bearer. When a terminal accesses a wireless communication network, an IP address is allocated, a PDN connection is created, and a default EPS bearer is simultaneously created. That is, the default bearer is created the first time a new PDN connection is created. The default bearer is maintained until the PDN connection is terminated. 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 parameters applied to the dedicated bearer are provided by the Policy and Charging Rule Function (PCRF). When generating the dedicated bearer, the PCRF can determine the QoS parameters by receiving the subscription information of the user from the Subscriber Profile Repository (SPR). Up to 15 dedicated bearers can be created, for example, up to 15, and in the current LTE system no four of the 15 are used. Therefore, up to 11 dedicated bearers can be created.

The EPS bearer includes a QoS Class Identifier (QCI) and an Allocation and Retention Priority (ARP) as basic QoS parameters. QCI is a scalar used as a criterion for accessing node-specific parameters that control bearer level packet forwarding treatment, where the scalar value is used by an operator that owns the base station And is pre-configured. For example, the scalar may be pre-configured with any one of the integer values 1-9. The main purpose of ARP is to determine if the establishment / modification request of the bearer is accepted or needed to be rejected if resources are limited. ARP may also be used to determine which bearer (s) to drop by the base station during exceptional resource limitations, such as at handover.

EPS bearer is divided into GBR (Guaranteed Bit Rate) bearer and non-GBR bearer according to QCI resource type. The default bearer is always a non-GBR bearer, and the dedicated bearer may be a GBR or non-GBR bearer. In addition to QCI and ARP, the GBR type bearer has QoS parameters GBR and MBR (Maximum Bit Rate), which means that a fixed resource is allocated for each bearer (bandwidth guarantee). On the other hand, non-GBR type bearers have aggregated maximum bit rate (AMBR) as QoS parameters in addition to QCI and ARP, which allocates the maximum bandwidth that can be used with other non-GBR type bearers Means receiving.

The P-GW (Packet Gateway) is a network node connecting between a wireless communication network (e.g., LTE network) and another network according to the present invention. The EPS bearer is defined between the terminal and the P-GW. The EPS bearer is further subdivided between nodes, and is defined as an RB between the UE and the base station, an S1 bearer between the base station and the S-GW, and an S5 / S8 bearer between the S-GW and the P- do. Each bearer is defined via QoS. QoS is defined through data rate, error rate, delay, and the like.

Therefore, once the QoS that the wireless communication system should provide as a whole is defined as the EPS bearer, QoS is determined for each interface. Each interface establishes a bearer according to the QoS it should provide.

The bearer of each interface provides the QoS of the entire EPS bearer divided by interface, so that the EPS bearer, the RB, and the S1 bearer all have a one-to-one relationship.

Hereinafter, a heterogeneous network will be described.

Simple cell segmentation of macro cells and micro cells makes it difficult to meet the growing demand for data services. Therefore, it is possible to operate the data service for small indoor and outdoor areas by using small cells such as pico cell, femto cell and wireless relay. Although the use of the small cells is not particularly limited, in general, the picocell can be used for a communication shadow area that is not covered only by a macrocell, an area where data service is required in a large amount, a so-called hot spot or a hotzone . A femto base station (femto eNB) can be generally used in an indoor office or a home. In addition, the wireless relay can compensate for the coverage of the macrocell. By configuring a heterogeneous network, not only the shadow areas of the data service can be eliminated, but also the data transmission speed can be increased.

5 is a diagram schematically illustrating a concept of a heterogeneous network composed of a macro base station, a femto base station, and a pico base station according to the present invention. 5 illustrates a heterogeneous network composed of a macro base station, a femto base station, and a pico base station, but the heterogeneous network may include a micro, a relay, or another type of base station. In the present invention, the base station may include the macro base station, the femto base station, the pico base station, the micro base station, the relay, and other types of base stations described above.

Referring to FIG. 5, a macro base station 510, a femto base station 520, and a pico base station 530 are operated together in a heterogeneous network. The macro base station 510, the femto base station 520, and the pico base station 530 provide macrocells, femtocells, and picocells, which are their own cell coverage, to the terminal.

The femto base station 520 is a low power wireless access point, for example, a base station for ultra small mobile communication used in a room such as a home or an office. The femto base station 520 can access the mobile communication core network using a home or office DSL or cable broadband. The femto base station 520 may support a self-organization function. Self-organization functions are classified into self-configuration, self-optimization, and self-monitoring.

The Self-Configuration function is a function that allows the base station to install itself based on the initial installation profile without going through the cell planning step. The self-organizing function shall meet the following requirements. First, the femto BS 520 must be able to establish a secured link with the Mobile Operation and Management Network (MON) according to the security policy of the network operator. Second, the femto base station management system (HNB Management System: HMS) and the femto base station 520 must be able to initialize the software download and activation of the femto base station 520. Third, the femto base station management system must be able to initiate the provision of transport resources to the femto base station 520 in order to establish a signaling link with the PLMN. Fourth, the femto base station management system must provide wireless network specific information to the femto base station 520 to automatically set the femto base station 520 to an operable state.

The self-optimization function is a function that optimizes the coverage and communication capacity according to the subscriber and traffic change by identifying the neighboring base stations and acquiring the information to optimize the list of neighboring base stations. Self-Monitoring is a function that controls the service performance through the collected information.

The femtocell can distinguish registered users from unregistered users and allow access only to registered users. (CSG), and the open user group (hereinafter referred to as "OSG ") is a group that allows access to only a registered user, and a cell that allows access only to registered users is called a closed group . It is also possible to operate these two methods in combination.

A base station that provides a femtocell service is called a home NodeB (HNB) or a home eNodeB (HeNB) in 3GPP. The femto base station 520 basically aims to provide a service specialized only to the members belonging to the CSG. In terms of providing the service, when the femto base station 520 provides services only to the CSG group, the cell provided by the femto base station 520 is referred to as a CSG cell.

Each CSG has a unique identifier, which is referred to as a CSG identity. A terminal can have a list of CSGs belonging to itself as a member. Such a CSG list is also called a whitelist. It is possible to confirm which CSG the CSG cell supports by reading the CSG ID included in the system information. The terminal that has read the CSG ID is regarded as a cell that can access the cell only when it is a member of the corresponding CSG cell, that is, when the CSG corresponding to the CSG ID is included in its own CSG whitelist.

The femto base station 520 does not always need to be allowed to connect to the CSG terminal. In addition, according to the configuration of the femto base station 520, it is also possible to allow connection of a terminal that is not a CSG member. The femtocell base station 520 determines whether to allow a terminal to access the base station 520. The configuration of the femtocell base station 520 means the setting of the operation mode of the femto base station 520. [ The operation mode of the femto base station 520 is classified into the following three types according to which terminal is provided with a service.

1) Closed access mode: A mode that provides services only to specific CSG members. The femto base station 520 provides a CSG cell.

2) Open access mode: A mode that provides services without restriction of a specific CSG member, like a normal BS. The femto base station 520 provides a general cell that is not a CSG cell.

3) Hybrid access mode: A mode in which a CSG service can be provided to a specific CSG member and a service is provided to a non-CSG member in the same manner as a general cell. The CSG cell is recognized as a CSG cell to the CSG member terminal and recognized as a general cell to the non-CSG member terminal. Such a cell is called a hybrid cell.

In a heterogeneous network in which a femtocell is operated together with a macro cell, when a femtocell is in an open access mode, a user can access a desired cell among a macro cell and a femtocell to use a data service.

When a femtocell is in a closed mode, for example, a general user using a macro cell can access a femtocell through a handover procedure even if the femtocell has superior signal quality and a low radio resource utilization rate There is no number.

The types of picocells provided by the pico base station 530 are called "coverage hole picocells" (hereinafter referred to as "coverage hole picocells") and "picocells for hot spots" ).

The Coverage Hole Pico cell is used when a terminal can not transmit / receive data through a macro cell and a terminal transmits / receives data via a pico cell instead of a macro cell. A hotspot picocell is a device in which a terminal transmits and receives data through a picocell in place of a macrocell in order to reduce the load of the macrocell, although the terminal can transmit and receive data through the macrocell. Hot spots may also refer to areas where the population is flooded or residential, or where demand traffic is high. Generally, a hot spot region may occur irrespective of an electro-magnetic field. In this case, the pico-cell may be divided into two types, i.e., an intra-frequency pico cell and an inter-frequency pico cell. .

An intra-frequency picocell refers to a picocell that uses the same frequency band as a macrocell. By reusing the same frequency resources in spatially separated areas, the same radio resources as the macro cells can be secured within the pico cell coverage. A picocell for most coverage holes corresponds to an intra-frequency picocell.

An inter-frequency picocell is a picocell that uses a different frequency band from a macrocell. When the signal of the macro cell received in the hot spot region is strong, the performance degradation due to the interference problem between the pico cell and the macro cell may occur. And can be used when a hot spot exists at a position close to the center of the macro cell.

In general, small cell is advantageous compared to macro cell in terms of throughput that can be provided for a single terminal because it serves a small area compared with a macro cell. However, in the current wireless communication system, once a terminal connected to a macro cell is located in a service area of a small cell, it can not receive service from a small cell without performing a handover. Also, in the case where the mobile station is moving, even if the mobile station is connected to the small cell through handover or the like, the coverage of the small cell is small, so handover frequently occurs, which is not preferable from the viewpoint of network efficiency.

6 shows an example of the arrangement of terminals and base stations in a heterogeneous network system.

Referring to FIG. 6, the heterogeneous network system includes a macro base station 600 that provides a service using frequency band 1 and a small base station 620 that provides a service using frequency band 2. The first base station 600 may provide a coverage area of a macro cell using frequency band 1 and the second base station may provide a service of a small cell using frequency band 2, Lt; RTI ID = 0.0 > coverage area. &Lt; / RTI >

The terminal 650 can set up an RRC connection with the macro base station 600 or the small base station 620 and receive the service. For example, when the terminal 650 accesses the service coverage area of the small base station 620 while the terminal 650 is in the RRC connection with the macro base station 600, May be better in the frequency band 2 of the small base station 620 than the frequency band 1 of the macro base station 600. [ In this case, in order for the MS 650 to receive a service from the small BS 620, an inter-frequency handover procedure from the macro base station 600 to the small base station 620, need.

If the terminal 650 is out of the service coverage area of the small base station 620 or the radio signal quality received by the terminal 650 is lower than the frequency band 2 of the small base station 620, 1, the inter-frequency handover procedure from the second base station 620 to the first base station 600 may also occur.

In this way, in order to receive a service from another base station having superior radio signal quality, for example, a small base station, a terminal connected to one base station, for example, a macro base station, has to perform a handover from a macro base station to a small base station After the handover procedure is completed, a service can be provided from the small base station.

That is, conventionally, in a heterogeneous network environment, a mobile station connected to a macro base station constituting a macro cell has excellent signal quality of a small base station constituting a small cell, and even when a radio resource utilization rate is low, Service was not provided. Also, even if a terminal is connected to a small base station constituting a small cell through a handover procedure or the like, the coverage of the small cell is relatively small, so that handover frequently occurs according to the movement of the terminal. This is true even if the terminal supports multi-element carriers. Accordingly, there is a need for a cell planning technique for distributing a load requiring a heavy load or a specific QoS in a heterogeneous network environment to a small cell without a handover procedure and efficiently transmitting data.

Hereinafter, the embodiments of the present invention will be described in detail with reference to the embodiments of the present invention, and the embodiments of the present invention can be applied to a heterogeneous network system including a macro cell and a small cell.

One embodiment includes a method for supporting additional data service or load distribution through a small cell while maintaining wireless connection and data service between a terminal and a macro cell in a heterogeneous network system. For example, the method can be applied when the terminal connected to the macro cell is located in an over-laid area with a service area of a macro cell and a service area of a small cell. This method is referred to as a procedure for configuring multiple wireless connections. Alternatively, the method may be referred to as an extended bearer establishment procedure or a bearer extension procedure.

The reason for supporting additional data service or load distribution through the small cell in the above embodiment can be roughly divided into two.

In order to support a service requesting a corresponding QoS when a base station is expected to fail or fail to satisfy a service requesting a specific QoS among a plurality of services requested by a terminal connected to a macro cell.

The other is that if a base station operating a macro cell (or a small cell) needs to control the load level within a macro cell (or small cell) based on a load management policy or the like, To support. For example, in the prior art, since the terminal supports only one QoS class at a time, the terminal itself can perform handover (for example, inter-frequency handover or inter-RAT handover However, in the present invention, in the case of a handheld device that simultaneously services various QoS classes, one of the QoS classes provided in the macrocell is used as a small cell for load balancing. Load balancing can be maintained by offloading. For example, if QoS classes A, B, and C are provided in a macro cell, QoS A can be offloaded to a small cell for load balancing.

In another embodiment of the present invention, a method for establishing an MBS and an MBS for delivering user data arriving at a macro base station to a UE via a small base station based on a radio link control (RLC)

The extended bearer establishment procedure or the bearer extension procedure includes negotiating an extended bearer setup between a macro base station and a small base station, adding a small cell as a secondary serving cell through RRC signaling to a mobile station in a macro base station, . &Lt; / RTI > For example, an extended bearer can be configured in a small cell in DRB format.

In a process of adding a small cell operated by a small base station as a serving cell in a state where an RRC connection is established between a macro cell operated by a macro base station and a terminal, layers and entities below the RLC layer in the DRB of the extended bearer / Reconfigure, where the layers and entities below the RLC layer include RLC entities, MAC entities and PHY layers. In this case, the extended bearer may be based on a dedicated EPS bearer. In this case, the RLC layer is available in both a UM mode and an AM mode.

In general, the UM mode is configured for data streaming or real-time data transmission such as Voice over Internet Protocol (VoIP). Therefore, it focuses on speed rather than reliability of data. AM mode, on the other hand, is more focused on data reliability and is suitable for data transmission that is less susceptible to large data transfers or transmission delays. In the present invention, in constructing multiple wireless connections for supporting additional data services through a small cell, consideration is given to radio resource management that can satisfy load balancing and user QoS through a small cell. Therefore, It is assumed that the RLC is configured in the AM mode.

7 shows a signaling procedure of a macro base station and a small base station for setting up an extended bearer according to the present invention. This procedure is a procedure for extending the bearer predefined between the macro cell and the UE to the small cell and the UE, and may be called an RLC extension procedure based on the RLC stage of the small cell in the extended bearer setup. The UE may be located in a superposed area of the coverage of the macro cell currently operated by the macro base station and the coverage of the small cell operated by the small base station. The macro base station is a base station for which a current mobile station and a radio bearer are established, and the small base station is a base station for setting up an extended radio bearer based on a radio bearer between a mobile station and a macro base station. It is also assumed that the macro cell and the small cell operate in different frequency bands.

Referring to FIG. 7, the macro base station transmits an RLC Extension Request message to a target small base station in step S700 when an extended bearer setting is required according to a predetermined criterion. The RLC extension request message may be transmitted from the macro base station to the small base station through the X2 interface. The RLC extension request message is a message requesting to set up a bearer extended between a small cell and a UE based on a radio bearer between a current UE and a macro BS. The radio bearer may be a radio bearer requiring a specific QoS. For example, at least one radio bearer may be set up in the UE according to a service or an application used by the UE, and a macro base station may transmit a service satisfying a specific QoS required by one of the at least one radio bearers If it is predicted that the UE can not provide or can not provide to the UE, the BS can request the UE to provide the extended bearer to the UE for the RB for the specific QoS. For example, when the macro base station needs to control the load level in the macro cell based on the load management policy or the like, the macro base station allows the service data of one of various QoS classes provided to the terminal to be supported through the small cell In order to establish a bearer extended from the small base station and the mobile station, a request may be made to provide a service to the mobile station.

Parameters that should operate identically for all serving cells with parameters configured to be macrocells in the current macro base station and configured for the UE, separately from the specific QoS information for the RB, may also be provided. Parameters related to MAC layer operation may be provided as the parameters. For example, parameters related to Discontinuous Reception (DRX) operation.

The small base station generates an RLC Extension Response message based on the RLC Extension Request message and transmits the RLC Extension Response message to the macro base station in operation S710. The RLC extended response message may be transmitted from the small base station to the macro base station through the X2 interface. For example, the RLC extension response message is a message indicating whether the small base station sets up an extended bearer based on the RLC extension request message. As another example, the RLC extension response message is a message indicating whether the small base station configures the RLC entity (and MAC entity) related to the extended bearer based on the RLC extension request message.

If the small base station agrees to set up the extended bearer, the RLC extension response message may be referred to as an RLC Extension Acknowledge (RLC) message. If the small base station refuses to set up the extended RB, The RLC extended response message may be referred to as an RLC Extension nonacknowledge message. When the small base station agrees to set up the extended bearer, the small base station sets an extended bearer, and the macro base station can provide a service such as data transmission to the mobile station through the extended bearer of the small base station. That is, the macro base station may forward data to the small base station through a backhaul network, and the small base station may transmit the data to the mobile station through the extended bearer.

8 is a conceptual diagram showing a connection configuration between a macro base station and a small base station according to the present invention.

8, data is transmitted from the Internet 800 to the P-GW 810, and the data is transmitted to the macro base station 830 via the S-GW 820. The QoS for the data may be set to a certain level. The macro base station 830 is a base station connected to the current terminal 850 and configured with a radio bearer.

The macro base station 830 includes an RRC entity 831, a PDCP entity 832, an RLC entity 833, a MAC entity 834, and a PHY layer 835. The structure and operation of each of the above entities include the contents described in Figs. 2 and 3.

In a normal mode without bearer extension (or RLC extension), the macro base station 830 receives the data at the PDCP entity 831 and processes the data based on control by the RRC entity 832, And transmits it to the terminal 850 through the RLC entity 833, the MAC entity 834, and the PHY layer 835. Meanwhile, in the bearer extension mode, the macro base station 830 can transmit (or provide) the data to the terminal 850 via the small base station 840. For this, the macro base station 830 and the small base station 840 can perform the procedure of FIG. 7 described above. For example, when the bearer extension mode is predicted to fail or fail due to poor network conditions such as network conditions or radio signal quality, QoS requested by the service for the data, and / And can be selected by a request of the macro base station 830 when it is determined that a service satisfying the QoS can be provided. Thus, the macro base station 830 and the small base station 840 can operate in the bearer extension mode. As another example, in the bearer extension mode, when the macro cell load control policy or the like is required in the base station operating the macro cell, the macro base station 830 transmits the small cell to the small base station 830, Lt; RTI ID = 0.0 > 840 < / RTI > That is, when the terminal 850 can simultaneously service various QoS classes, one of the QoS classes provided in the macro cell is offloaded to a small cell for load balancing to maintain the load balance The macro base station 830 and the small base station 840 can operate in the bearer extension mode.

The PDCP entity 831 of the macro base station 830 may forward the data to the RLC entity 843 of the small base station 840 through the backhaul network.

The small base station 840 includes an RLC entity 843, a MAC entity 844, and a PHY layer 845. In the bearer extension mode, the RLC entity 843 of the small base station 840 receives the user data from the PDCP entity 832 of the macro base station 830 and transmits it to the MAC entity 844 and the PHY layer 845 To the terminal 850. In this case, the terminal 850 can receive the general service from the macro base station 830, and can receive the data for the service requesting the specific QoS from the small base station 830. Since the macro base station 830 and the small base station 840 operate in the bearer expansion mode, it is possible to transmit data requiring a specific QoS and to distribute the downlink load without a separate handover procedure.

9 is a flowchart illustrating signaling between a terminal, a macro base station, and a small base station according to an exemplary embodiment of the present invention. As described above, the terminal can be located in a superposed area of a macro cell managed by a macro base station and a small cell managed by a small base station. It is also assumed that the macro cell and the small cell use different frequency bands.

Referring to FIG. 9, the MS performs an RRC Connection Establishment procedure with the macro base station (S900). The RRC connection setup procedure includes a step in which the UE transmits an RRC connection request message to the macro base station, a step in which the macro base station transmits an RRC connection setup message to the UE, and a step in which the UE transmits an RRC connection setup complete message to the macro base station do. The purpose of the RRC connection establishment procedure is to establish an RRC connection.

The terminal performs measurement report to the macro base station (S910). The measurement report includes the measurement result for the small cell. For example, the UE may enter a service area of the small cell in a state where a macro base station and an RRC connection are established, and the UE may report a measurement result of the small cell to the macro base station.

In general, the UE performs measurements to determine whether neighbor cells exist or not. At this time, the neighboring cells existing in the intra-frequency transmit signals through the same frequency band as the current serving cell. Therefore, it is possible to measure neighbor cells at the same time while transmitting and receiving with the serving cell. However, since neighboring cells existing in the inter-frequency transmit signals through a frequency band different from that of the serving cell, the UE temporarily suspends transmission / reception with the serving cell, retunes the RF chain, A signal for a frequency band identified as having a possibility of being present. Here, an RF chain refers to a portion of an antenna in which a filter and a power amplifier are combined.

After the terminal performs the measurement, the measurement result is reported to the base station of the serving cell. This is referred to as a measurement report, which includes periodic reporting and event-triggered reporting. In the event-triggered reporting, the triggering of the event to be reported includes an A1 event (when the measurement result of the serving cell is larger than a predetermined threshold), an A2 event (when the measurement result of the serving cell is smaller than a predetermined threshold ), A3 event (when the measurement result of the neighboring cell is larger than the measurement result of the serving cell by a predetermined offset), A4 event (when the measurement result of the neighboring cell is larger than the predetermined threshold), A5 event (When the measurement result of the neighboring cell is larger than the predetermined threshold) or B2 (when the result is smaller than the measurement result of the neighboring cell by a predetermined offset), and in case of inter-RAT mobility Event (when the measurement result of the serving cell is smaller than the measurement result of the neighboring cell by a predetermined threshold value).

The measurement report can be performed through a measurement report message. The measurement report message includes a reference signal received power (RSRP), a reference signal received quality (RSRQ) value, a PCI (physical cell ID) .

The macro base station determines whether to set up an extended bearer based on the measurement report. When the macro base station determines to set up the extended bearer, it generates an RLC extension request message and transmits it to the small base station (S920). The RLC extension request message may be transmitted to the small base station through the X2 interface. The RLC extension request message includes user context information or RLC configuration information.

The user context information included in the RLC extension request message may include information as shown in Table 1, for example.

IE / group name
(IE / Group Name) Presence IE type (IE type) and reference C-RNTI M INTEGER (0..65536) EPS Bearer ID M INTEGER (0..15) DRB ID M or O INTEGER (0..31) QCI M INTEGER (0..255) The UE-specific MAC parameters O MAC-MainConfig About GBR QoS O See Table 2

Referring to Table 1, the user context information includes information elements (IEs) indicating C-RNTI (Cell Radio Network Temporary Identifier), EPS bearer ID, DRB ID, QCI, UE- : Information Element) or a group. In Table 1, M in the Presence field indicates " Mandatory ", and O indicates " Optional ". The C-RNTI means a C-RNTI allocated to the UE at the current macro base station. The C-RNTI may be replaced with a Globally Unique Temporary UE Identity (GUTI), an International Mobile Subscriber Identity (IMSI), or an International Mobile Equipment Identity (IMEI). In this case, the C-RNTI is not duplicated in all UEs configured in at least one of the macro cell and the small cell. The EPS bearer ID indicates the ID of the EPS bearer that the macro base station currently wants to transmit data through the EPS bearer through the small base station. The DRB ID is an ID of a DRB included in the EPS bearer and used for data transmission. The DRB ID may be configured as required or optional. For example, if the DRB is configured first in the macro base station and the ID value is set in the DRB, then the DRB ID value must be mandatory when transmitting to the small base station. On the other hand, if the small base station can initially generate a DRB for the EPS bearer, the DRB ID value may be optional.

The QCI indicates a QoS class ID required for data (service) to be transmitted through the EPS bearer. The UE-specific MAC parameter is a parameter related to the configuration of a MAC layer transmitted to a specific UE. The UE-specific MAC parameter may be configured in the form of a MAC-MainConfig information element. The UE-specific MAC parameters may include uplink common channel configuration information, DRX configuration information, time alignment timer only, and Power Headroom Report configuration information.

The GBR QoS information is an information element indicating the maximum and guaranteed bit rate of the GBR E-RAB for the uplink or downlink. The GBR QoS information may be selectively configured. For example, the GBR QoS information may be additionally configured only when GBR configuration is requested for the corresponding EPS bearer. The GBR QoS information may include information as shown in Table 2.

IE / group name
(IE / Group Name) existence
(Presence) IE type (IE type)
And references Shiman's description
(Semantics description) E-RAB maximum bit rate
Downlink M Bit rate
(Bit Rate)
The maximum bit rate for the bearer downlink (i.e., EPC to E-UTRAN). E-RAB maximum bit rate
Uplink M Bit rate Uplink (i.e., from E-UTRAN to EPC) bearer. E-RAB guaranteed bit rate
Downlink M Bit rate

The downlink (i.e., EPC to E-UTRAN) guaranteed bit rate for the bearer (if there is data to convey). E-RAB guaranteed bit rate
Uplink M Bit rate

Uplink to the bearer (ie from E-UTRAN to EPC) guaranteed bit rate (if there is data to forward).

Referring to Table 2, the GBR QoS information includes an E-RAB maximum bit rate downlink field, an E-RAB maximum bit rate uplink field, an E-RAB guaranteed bit rate downlink field, and an E-RAB guaranteed bit rate uplink field . The E-RAB maximum bit rate downlink field indicates the maximum bit rate of the downlink for the E-RAB bearer. That is, the E-RAB bearer logically connects the EPC and the E-UTRAN, and the E-RAB maximum bit rate downlink field indicates the maximum bit rate from the EPC to the E-UTRAN. The bit rate is an information element indicating the number of bits transmitted in the E-UTRAN in the uplink or in the E-UTRAN in the downlink for a predetermined period of time. The E-RAB maximum bit rate uplink field indicates the maximum bit rate of the uplink to the E-RAB bearer. The E-RAB guaranteed bit rate downlink field represents the guaranteed bit rate of the downlink for the E-RAB bearer. The E-RAB guaranteed bit rate uplink field represents the guaranteed bit rate of the downlink for the E-RAB bearer.

Meanwhile, the RLC configuration information included in the RLC extension request message may include information as shown in Table 3, for example.

IE / group name
(IE / Group Name) Presence IE type (IE type) and reference C-RNTI M INTEGER (0..65536) EPS Bearer ID M INTEGER (0..15) DRB ID M INTEGER (0..31) RLC parameter M Table 4 RLC-Config IE Reference

Referring to Table 3, the RLC configuration information may include a C-RNTI, an EPS bearer ID, a DRB ID, and an RLC parameter. The RLC parameter is defined in the RLC-Config information element, and the RLC-Config information element can be used to specify the RLC configuration of SRBs and DRBs. The RLC-Config information element may specifically include parameters as shown in Table 4. In the present invention, the RLC parameter field of Table 3 may include all of the parameters of Table 4 below, or may include some of the parameters of Table 4 below. For example, the RLC parameter field may be configured as a parameter for one of the UM / AM modes among the parameters shown in Table 4, and may be configured to be limited at all times by only the parameters for the AM mode.

- ASN1START

RLC-Config :: = CHOICE {
am SEQUENCE {
UL-AM-RLC UL-AM-RLC,
dl-AM-RLC DL-AM-RLC
},
um-Bi-Directional SEQUENCE {
UL-UM-RLC UL-UM-RLC,
dl-UM-RLC DL-UM-RLC
},
um-Uni-Directional-UL SEQUENCE {
UL-UM-RLC UL-UM-RLC
},
um-Uni-Directional-DL SEQUENCE {
dl-UM-RLC DL-UM-RLC
},
...
}

UL-AM-RLC :: = SEQUENCE {
t-PollRetransmit T-PollRetransmit,
pollPDU PollPDU,
pollByte PollByte,
maxRetxThreshold ENUMERATED {
t1, t2, t3, t4, t6, t8, t16, t32}
}

DL-AM-RLC :: = SEQUENCE {
t-Reordering T-Reordering,
t-StatusProhibit T-StatusProhibit
}

UL-UM-RLC :: = SEQUENCE {
sn-FieldLength SN-FieldLength
}

DL-UM-RLC :: = SEQUENCE {
sn-FieldLength SN-FieldLength,
t-Reordering T-Reordering
}

SN-FieldLength :: = ENUMERATED {size5, size10}

T-PollRetransmit :: = ENUMERATED {
ms5, ms10, ms15, ms20, ms25, ms30, ms35,
ms40, ms45, ms50, ms55, ms60, ms65, ms70,
ms75, ms80, ms85, ms90, ms95, ms100, ms105,
ms110, ms115, ms120, ms125, ms130, ms135,
ms140, ms145, ms150, ms155, ms160, ms165,
ms170, ms175, ms180, ms185, ms190, ms195,
ms200, ms205, ms210, ms215, ms220, ms225,
ms230, ms235, ms240, ms245, ms250, ms300,
ms350, ms400, ms450, ms500, spare9, spare8,
spare7, spare6, spare5, spare4, spare3,
spare2, spare1}

PollPDU :: = ENUMERATED {
p4, p8, p16, p32, p64, p128, p256, pInfinity}

PollByte :: = ENUMERATED {
kB25, kB50, kB75, kB100, kB125, kB250, kB375,
kB500, kB750, kB1000, kB1250, kB1500, kB2000,
kB3000, kBinfinity, spare1}

T-Reordering :: = ENUMERATED {
ms0, ms5, ms10, ms15, ms20, ms25, ms30, ms35,
ms40, ms45, ms50, ms55, ms60, ms65, ms70,
ms75, ms80, ms85, ms90, ms95, ms100, ms110,
ms120, ms130, ms140, ms150, ms160, ms170,
ms180, ms190, ms200, spare1}

T-StatusProhibit :: = ENUMERATED {
ms0, ms5, ms10, ms15, ms20, ms25, ms30, ms35,
ms40, ms45, ms50, ms55, ms60, ms65, ms70,
ms75, ms80, ms85, ms90, ms95, ms100, ms105,
ms110, ms115, ms120, ms125, ms130, ms135,
ms140, ms145, ms150, ms155, ms160, ms165,
ms170, ms175, ms180, ms185, ms190, ms195,
ms200, ms205, ms210, ms215, ms220, ms225,
ms230, ms235, ms240, ms245, ms250, ms300,
ms350, ms400, ms450, ms500, spare8, spare7,
spare6, spare5, spare4, spare3, spare2,
spare1}

- ASN1STOP

9, when the small base station determines to perform the extended bearer setup based on the RLC extension request message, the small base station transmits the RLC extension request message to the RLC layer based on the user context information or the RLC configuration information included in the RLC extension request message The layer and the entity are configured / reconfigured (S930). Herein, the layers and entities below the RLC layer include an RLC entity, a MAC entity, and a PHY layer. That is, the small base station constructs / reconfigures the RLC entity, the MAC entity, and the PHY layer based on the context information or the RLC configuration information included in the RLC extension request message.

For example, a small base station can use an E-RAB already configured in a small cell. The macro cell configured in the macro base station and the small cell configured in the small base station are configured with QoS for each E-RAB based on the E-RAB setup configured in the MME. Therefore, based on the QoS (or QCI) in the E-RAB configured to support the UE in the current macro cell, the small base station can provide the corresponding service using the E-RAB configured in the small cell You can check whether there is. The small base station can confirm based on whether the E-RAB configured in the small cell satisfies the QoS (or QCI) in the E-RAB configured to support the service in the current macrocell. In this case, the small base station checks whether the service can be provided using the E-RAB configured in the small cell based on the user situation information, and if the service can be provided, -RAB < / RTI >

As another example, the small base station may not have the E-RAB configuration for the terminal in the small cell or the E-RAB that is already configured may not be available. In this case, the small base station can additionally configure a new DRB corresponding to the E-RAB configuration configured through the existing macro cell in the small cell. In this case, based on the QoS for the E-RAB of the macro cell or the RLC configuration information, the small base station can configure the RLC below the small cell. At this time, there is no configuration for the upper end of the RLC entity for the DRB newly formed in the small cell, that is, the PDCP entity, or the like, or it may be configured in a default state. In configuring the RLC sub-stage, the small base station may be based on the user context information included in the RLC extension request message. Alternatively, the small base station can directly obtain the RLC configuration information through the RLC extension request message and configure the RLC entity. Based on the RLC configuration information, the MAC configuration information and PHY configuration information for the following entity can be obtained and a MAC entity and a PHY entity can be configured.

The small base station generates an RLC Extension Response message and transmits it to the macro base station (S940). The RLC extended response message may be transmitted to the macro base station via the X2 interface. If the RLC extension response message is an RLC extension grant message, the RLC extension response message may include parameters for the RLC sub-step configured in the small base station. In this case, the RLC extended response message may include information as shown in Table 5, for example.

IE / group name
(IE / Group Name) Presence IE type (IE type) and reference C-RNTI M INTEGER (0..65536) EPS Bearer ID M INTEGER (0..15) DRB ID M or O INTEGER (0..31) RLC extension M INTEGER (0..1) or
INTEGER (0..3) RLC parameter O RLC-Config MAC parameter O MAC-MainConfigSCell PHY parameter O Composed of RadioResourecConfigCommonSCell and PhysicalConfigDedicatedSCell

Referring to Table 5, the RLC extension field may include only a field value that indicates simply disable / permit. However, in this case, a value indicating the reason why the RLC extension can not be performed may be added and defined as an extended field value. For example, if the value of the RLC extension field is 0, it indicates 'not possible', and if it is 1, it indicates 'allowed'. As another example, if the value of the RLC extension field is 0, it means' not possible (no negotiation) '; if 1,' not possible (QCI support for EPS bearer is not available - It may indicate 'reserved'. The MAC parameter field includes a 'MAC-MainConfigSCell' information element indicating MAC parameter configuration information applied to a secondary serving cell (Scell) configured in a small cell, and the PHY parameter field is a sub- A 'RadioResourecConfigCommonSCell' information element indicating system information that is limited to a cell, and a 'PhysicalConfigDedicatedSCell' information element indicating a UE-specific PHY parameter applied to a sub-serving cell configured in a small cell. Alternatively, the MAC parameter field and the PHY parameter field may be represented by a 'RadioResourceConfigDedicatedSCell' information element including a 'MAC-MAINConfigSCell' information element and a 'PhysicalConfigDedicatedSCell'.

Although this embodiment has been described as being performed before step S940, it is to be understood that this is only an example and that step S930 may be performed simultaneously with or after step S940. That is, the small base station can construct or reconfigure the RLC entity and the MAC entity simultaneously with or after transmitting the RLC extended response message to the macro base station.

The macro base station may perform an RRC connection reconfiguration procedure to add a secondary serving cell based on the parameters of the RLC extension response message (S950). The RRC connection reconfiguration procedure includes a step in which the macro base station generates an RRC connection reconfiguration message and transmits the RRC connection reconfiguration message to the UE, and the UE transmits an RRC connection reconfiguration completion message to the macro base station. The RRC connection reconfiguration message may include secondary serving cell configuration information. That is, the RRC connection reconfiguration message may include a secondary serving cell configuration information field including contents configuring a small cell as a secondary serving cell. In this case, the UE can add the small cell configured in the small base station as a secondary serving cell based on the RRC connection reconfiguration message, and configure / reconfigure layers and entities below the RLC layer. The MS may transmit an RRC connection reconfiguration completion message to the macro base station in response to the RRC connection reconfiguration message.

The macro base station transmits the data to the terminal via the small base station (S960). The terminal can receive the data on the small cell configured in the small base station. The macro base station transmits data to the terminal via the small base station. The macro base station forwards the data to the small base station through the backhaul network. The small base station transmits the data forwarded from the macro base station to the terminal through the small cell. .

In such a case, the macro cell configured in the macro base station and the terminal on the small cell configured in the small base station can be substantially simultaneously provided with services. The terminal can receive data through different frequencies used by the macro cell and the small cell. From the viewpoint of a multi-element carrier system, a terminal is effective in providing different services on different frequencies aggregated at a single base station. That is, in this case, the macro cell is treated as a primary serving cell (Pcell) and the small cell can be treated as a secondary serving cell (Scell).

10 is a flowchart illustrating an operation of a macro base station in a bearer extension procedure according to an exemplary embodiment of the present invention.

Referring to FIG. 10, the macro base station receives a measurement report from the terminal (S1000). Here, the macro base station is in a state of being connected to the terminal in the current RRC. That is, the macro base station may be a base station that is currently set up with a terminal and a radio bearer, and the small base station may be a base station that is requested to set up an extended bearer based on a radio bearer between the terminal and the macro base station. The measurement report includes the measurement result for the small cell operated by the small base station. The measurement report includes periodic reporting and event-triggered reporting. It is assumed that the small cell uses a different frequency from the macro cell operated by the macro base station. Measurement reports can be performed through measurement report messages, which may include RSRP and RSRQ values, PCI, CGI, and so on.

The macro base station determines whether it is necessary to set up an extended bearer based on the measurement report (S1010). For example, when the macro base station does not satisfy or expects that a service requesting a specific QoS is not satisfied among a plurality of services requested by a terminal connected to a macro cell and / It can be determined that the extended bearer setup is performed. As another example, when the macro base station needs to control the load level in the macro cell based on the load management policy, it can decide to perform the extended bearer setup to support through the small cell. That is, when the UE can simultaneously service various QoS classes, the macro base station allocates one of the QoS classes provided in the macro cell to the small cell for load balancing to maintain the load balance It can be determined to perform the extended bearer setup.

When it is determined to perform the extended bearer setup, the macro base station generates an RLC extension request message and transmits the RLC extension request message to the small base station in step S1020. The macro base station can transmit the RLC extension request message to the small base station via the X2 interface. The RLC extension request message includes user context information or RLC configuration information. The user context information may include the information of Tables 1 and 2, and the RLC configuration information may include the information of Tables 3 and 4 above.

The macro base station receives the RLC extended response message from the small base station (S1030). The RLC extended response message may be received from the small base station via the X2 interface. The RLC extended response message may include the information in Table 5 above. The RLC extension response message may include parameters for the RLC sub-step configured by the small base station. That is, it may include parameters for the RLC entity, the MAC entity, and the PHY layer.

The macro base station generates an RRC connection reconfiguration message and transmits the RRC connection reconfiguration message to the terminal (S1040). The macro base station generates an RRC connection reconfiguration message on the basis of the parameters for the RLC sub-stage configured by the small base station, and transmits the RRC connection reconfiguration message to the UE. The RRC connection reconfiguration message may comprise secondary serving cell configuration information, which configures the small cell as a secondary serving cell. That is, the RRC connection reconfiguration message may include a secondary serving cell configuration information field including contents configuring a small cell as a secondary serving cell. In this case, the UE can configure the small cell as a secondary serving cell based on the RRC connection reconfiguration message, and perform configuration / reconfiguration for the RLC sub-stage.

The macro base station receives an RRC connection reconfiguration completion message from the terminal in response to the RRC connection reconfiguration message (S1050).

The macro base station forwards the data for the specific service to the small base station (S1060). For example, the data for the specific service may be data for a service that does not satisfy the QoS or is predicted to fail. As another example, if the macro base station needs to control the load level in the macro cell based on the load management policy or the like, the data for the specific service may include data for a service that is offloaded to the small cell .

The macro base station can forward data for the specific service to the small base station through the backhaul network. The forwarding of the data may be performed by the RLC entity of the small cell in the PDCP entity of the macro cell.

11 is a flowchart illustrating operations of a small base station in a bearer extension procedure according to an exemplary embodiment of the present invention.

Referring to FIG. 11, the small base station receives an RLC extension request message from the macro base station (S1100). The macro base station is in the RRC connection state with the terminal. That is, the macro base station may be a base station that is currently set up with a mobile station and a radio bearer, and the small base station may be a base station that is requested to establish an extended bearer based on a radio bearer between the mobile station and the macro base station. It is assumed that the small cell uses a different frequency from the macro cell operated by the macro base station. The small base station can receive the RLC extension request message from the macro base station via the X2 interface. The RLC extension request message includes user context information or RLC configuration information. The user context information may include the information of Tables 1 and 2, and the RLC configuration information may include the information of Tables 3 and 4 above.

If the RLC Extension Request message is received, the RLC Extension Request message is transmitted to the RLC Extension Request message. If the RLC Extension Request message includes the RLC Extension Request message, The MAC entity and the PHY layer are configured / reconfigured (S1110).

As another example, the small base station may not have the E-RAB configuration for the terminal in the small cell or the E-RAB that is already configured may not be available. In this case, the small base station can additionally configure a new DRB corresponding to the E-RAB configuration configured through the existing macro cell in the small cell. In this case, based on the QoS for the E-RAB of the macro cell or the RLC configuration information, the small base station can configure the RLC entity in the small cell. At this time, the upper end of the RLC entity for the newly configured DRB in the small cell, that is, the configuration for the PDCP entity or the like, is not configured or can be configured in a default state. In configuring the RLC sub-entity, the small base station may be based on the user context information included in the RLC extension request message. Alternatively, the small base station may directly obtain the RLC configuration information through the RLC extension request message, and may generate MAC configuration information and PHY configuration information for the entity based on the RLC configuration information.

If the small base station determines not to perform the extended bearer setup, step S1110 may be omitted.

The small base station generates an RLC extended response message and transmits the RLC extended response message to the macro base station (S1120). The RLC extended response message may be transmitted to the macro base station via the X2 interface. The RLC extension response message may include parameters related to the RLC sub-stage configured in the small base station. The RLC extended response message may include the information in Table 5 above.

The small base station receives data for a specific service from the macro base station (S1130). For example, the data for the specific service may be data for a service that does not satisfy or can not meet a specific QoS in the macro cell of the macro base station. In another example, the data for the specific service may be data for a service for offloading the small cell when the load level in the macro cell needs to be controlled.

The small base station can receive data for the specific service from the macro base station through the backhaul network. The forwarding of the data may be performed by the RLC entity of the small cell in the PDCP entity of the macro cell.

The small base station transmits the forwarded data to the mobile station (S1140). And the small base station can transmit the data to the terminal through the small cell in which the extended bearer is set.

In this case, for example, the small base station does not satisfy the QoS demanded by the service for the data due to poor network conditions such as the radio signal quality of the macro cell, but the small cell provides a service satisfying the QoS It is possible to smoothly transmit the data to the terminal.

12 is a flowchart illustrating an operation of a UE in a bearer extension procedure according to an exemplary embodiment of the present invention.

Referring to FIG. 12, the UE performs measurement report to the macro base station (S1200). Here, the macro base station is in the RRC connection state with the terminal. That is, the macro base station may be a base station that is currently set up with a terminal and a radio bearer, and the small base station may be a base station that is requested to set up an extended bearer based on a radio bearer between the terminal and the macro base station. The measurement report includes measurement results for neighboring cells, particularly small cells. The measurement report includes periodic reporting and event-triggered reporting. It is assumed that the small cell uses a different frequency from the macro cell operated by the macro base station. The measurement report may be performed through a measurement report message, which may include RSRP and RSRQ values, PCI, CGI, and the like.

The MS receives an RRC connection reconfiguration message from the macro base station (S1210). The RRC connection reconfiguration message may include parameters for the RLC sub-step of the small cell. Further, the RRC connection reconfiguration message may include secondary serving cell configuration information that configures the small cell as a secondary serving cell. That is, the RRC connection reconfiguration message may include a secondary serving cell configuration information field including contents configuring a small cell as a secondary serving cell.

In this case, the UE can configure the small cell as a secondary serving cell and perform configuration / reconfiguration for an RLC sub-entity based on the RRC connection reconfiguration message (S1220). The MS may transmit an RRC connection reconfiguration completion message to the macro base station in response to the RRC connection reconfiguration message (S1230).

The terminal receives data for the specific service from the small base station (S1240). The terminal receives data for the specific service from the small base station through the small cell in which the small base station sets the extended bearer. For example, the data for the specific service may be data that the macro base station predicts that the specific QoS requested by the specific service does not satisfy or can not be forwarded to the small base station. Since the radio resource allocation opportunity and the resource allocation amount through the small cell are generally larger or larger than the macro cell, even if the macro cell does not satisfy the specific QoS, the UE can perform the service satisfying the specific QoS through the small cell And can be provided from the small base station. As another example, the data for the specific service may be data for a service that the macro base station forwarded to the small base station so as to offload the small cell to the small cell when control is required on the load level in the macro cell.

In this case, the small cell uses a frequency different from that of the macro cell, and the macro cell can be regarded as a main serving cell and the small cell as a secondary serving cell in the context of a terminal.

13 is a flowchart illustrating signaling between a terminal, a macro base station, and a small base station according to another example of the present invention. As described above, the terminal can be located in a superposed area of a macro cell managed by a macro base station and a small cell managed by a small base station. It is also assumed that the macro cell and the small cell use different frequency bands. The embodiment of FIG. 13 includes a procedure in which a macro base station transmits uplink transmission path related configuration information to a mobile station for uplink transmission through a small cell.

Referring to FIG. 13, the MS performs an RRC connection establishment procedure with the macro base station (S1300). The RRC connection setup procedure includes a step in which the UE transmits an RRC connection request message to the macro base station, a step in which the macro base station transmits an RRC connection setup message to the UE, and a step in which the UE transmits an RRC connection setup complete message to the macro base station do. The purpose of the RRC connection establishment procedure is to establish an RRC connection.

The terminal performs measurement report to the macro base station (S1310). The measurement report includes the measurement result for the small cell. For example, the UE may enter a service area of the small cell in a state where a macro base station and an RRC connection are established, and the UE may report a measurement result of the small cell to the macro base station.

The measurement report includes periodic reporting and event-triggered reporting. It is assumed that the small cell uses a different frequency from the macro cell operated by the macro base station. Measurement reports can be performed through measurement report messages, which may include RSRP and RSRQ values, PCI, CGI, and so on.

The macro base station determines whether to set up an extended bearer based on the measurement report. When the macro base station determines to set up the extended bearer, it generates an RLC extension request message and transmits it to the small base station (S1320). The macro base station can determine whether handover to the small cell or an establishment of an extended bearer in the small cell based on the measurement report and deliver the message to the small base station including the small cell. The present invention is limited to a procedure in which the macro base station requests the establishment of the extended bearer, that is, the RLC extension, to the small cell included in the small base station. The RLC extension request message may be transmitted to the small base station through the X2 interface. The RLC extension request message includes user context information including a serving cell index (ServIndex) or a secondary serving cell index (Scell index) for a secondary serving cell to which the extended bearer is mapped in the small base station.

The user context information included in the RLC extension request message may include information as shown in Table 6, for example.

IE / group name
(IE / Group Name) Presence IE type (IE type) and reference C-RNTI M INTEGER (0..65536) EPS Bearer ID M INTEGER (0..15) DRB ID M or O INTEGER (0..31) QCI M INTEGER (0..255) About GBR QoS O See Table 2 Secondary serving cell (Scell) index M INTEGER (0..7)

Referring to Table 6, the user context information may include information elements (IEs) or groups indicating C-RNTI, EPS bearer ID, DRB ID, QCI, secondary serving cell index and GBR QoS information. In Table 6, M of the Presence field indicates " Mandatory ", and O indicates " Optional " The C-RNTI means a C-RNTI allocated to the UE at the current macro base station. The C-RNTI may be replaced with a GUTI, an IMSI, or an IMEI. In this case, the C-RNTI is not duplicated in all UEs configured in at least one of the macro cell and the small cell. The EPS bearer ID indicates the ID of the EPS bearer that the macro base station currently wants to transmit data through the EPS bearer through the small base station. The DRB ID is an ID of a DRB included in the EPS bearer and used for data transmission. The DRB ID may be configured as required or optional. For example, if the DRB is configured first in the macro base station and the ID value is set in the DRB, then the DRB ID value must be mandatory when transmitting to the small base station. On the other hand, if the small base station can initially generate a DRB for the EPS bearer, the DRB ID value may be optional.

The QCI indicates a QoS class ID required for data (service) to be transmitted through the EPS bearer.

The GBR QoS information is an information element indicating the maximum and guaranteed bit rate of the GBR E-RAB for the uplink or downlink. The GBR QoS information may be selectively configured. For example, the GBR QoS information may be additionally configured only when GBR configuration is requested for the corresponding EPS bearer. The GBR QoS information may include information as shown in Table 2 above.

The sub-serving cell index is an index value of a secondary serving cell to be additionally configured for the UE in the small base station. The index value of the secondary serving cell to be newly added (configured) is managed by the macro base station. That is, the macro base station generates information on the index value of the secondary serving cell and transmits it to the small base station.

Referring again to FIG. 13, when the small base station determines to perform the extended bearer setup based on the RLC extension request message, the small base station further configures the extended bearer to the small cell, Configuration / reconfiguration (S1330). The extended bearer includes a DRB. For example, if the small base station has decided to perform the extended bearer setup, a new DRB can be additionally configured in the small cell. The DRB may have the same EPS ID value and QoS characteristic as the DRB configured in the macro cell (i.e., main serving cell) currently configured in the macro base station. The DRB may be configured based on configuration information for the RLC layer. The MAC and PHY layers may be configured based on the configuration information for the small cell.

The small base station can configure / reconfigure RLC sub-stages based on the user context information included in the RLC extension request message. Hereinafter, an RLC layer or lower layer includes an RLC entity, a MAC entity, and a PHY layer. That is, the small base station can configure / reconfigure RLC entity, MAC entity, and PHY layer based on the context information included in the RLC extension request message.

The small base station generates an RLC Extension Response message and transmits it to the macro base station (S1340). The RLC extended response message may be transmitted to the macro base station via the X2 interface. If the RLC extension response message is an RLC extension grant message, the RLC extension response message may include parameters for an RLC sub-step configured in the extended bearer of the small base station. The RLC extended response message may include information as shown in Table 5 above.

On the other hand, when the extended bearer is set in the small cell, the RLC entity for the corresponding DRB configured in the macro cell performs a re-establishment procedure. This is necessary to receive as much data as possible among the data received from the RLC entity for the corresponding DRB of the macro cell in the RLC entity for the extended bearer of the small cell. For example, if the RLC entity for the corresponding DRB of the macro cell is a Transparent Mode (TM) RLC entity, all RLC SDUs (Service Data Units) are discarded. As another example, when the RLC entity for the corresponding DRB of the macro cell is an Unacknowledged Mode (UM) RLC entity, all possible UMD (Unacknowledged Mode Data) PDUs (Protocol Data Units) RLC SDU, transmits it to an upper layer (PDCP), and discards the remaining UMD PDUs. As another example, when the RLC entity for the corresponding DRB of the macro cell is an Acknowledged Mode (AM) RLC entity, a byte segment of all possible Acknowledged Mode Data (PDU) PDUs configurable as RLC SDUs ), And discards the remaining AMD PDUs and byte segments in the receiver. And discards all RLC SDUs and AMD PDUs in the transmission. It also discards the RLC control PDUs.

When a procedure for resetting the RLC entity for the corresponding DRB configured in the macro cell proceeds, all the timers related to the RLC entity may be stopped or reset. In addition, all the RLC entity related state variables may be reset to their initial values.

In this embodiment, step S1330 has been described as being performed before step S1340, but this is merely an example, and step S1330 may include what is performed simultaneously with or after step S1340. That is, the small base station can construct or reconfigure the RLC entity and the MAC entity simultaneously with or after transmitting the RLC extended response message to the macro base station.

The macro base station may perform an RRC connection reconfiguration procedure to add a secondary serving cell based on the parameters for the RLC lower layer of the extended bearer included in the RLC extended response message (S1350). The RRC connection reconfiguration procedure includes a step in which the macro base station generates an RRC connection reconfiguration message and transmits the RRC connection reconfiguration message to the UE, and the UE transmits an RRC connection reconfiguration completion message to the macro base station. The RRC connection reconfiguration message may include DRB configuration information and secondary serving cell configuration information as well as parameters for the RLC sub-step of the extended bearer. At this time, the DRB configuration information may include information on an uplink transmission path. For example, the uplink transmission path may be indicated by a small cell (specifically, the extended bearer of a small cell) configured in a small base station. The secondary cell configuration information is information for adding a secondary serving cell. The secondary serving cell configuration information may include the secondary serving cell index which is an index for the small cell to be added to the secondary serving cell. The RRC connection reconfiguration message may include, for example, the following syntax.

Table 7 shows an example of the RRC connection reconfiguration message according to the present invention.

DRB-ToAddModList :: = SEQUENCE (SIZE (1..maxDRB)) OF DRB-ToAddMod

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
ul-transmissionServingCell INTEGER (0..7) OPTIONAL, - Cond
Setup
...
}

Referring to Table 7, the RRC connection reconfiguration message includes DRB-ToAddModList which is DRB configuration information including at least one DRB-ToAddMod for DRB setup. The size of the DRB-ToAddModList can be set from 1 to the maximum number of DRBs (max DRB) and includes DRBs to be set up and changed. The DRB-ToAddModList may include the ID of the added DRB and the ID of the EPS bearer including the DRB. In addition, the RRC connection reconfiguration message includes an ul-transmissionServingCell which is DRB configuration information for the uplink transmission path. The ul-transmissionServingCell may be set to the same value as the serving cell index or the secondary serving cell index value, and indicates an uplink transmission path for the corresponding DRB. That is, in this case, the uplink data of the service for the DRB of the UE can be transmitted through the serving cell index or the secondary serving cell index indicated by the secondary serving cell index. If at least one uplink transmission path between a specific DRB and a specific serving cell is set as described above, an uplink transmission path for DRBs for which uplink transmission paths between a specific DRB and a specific serving cell are not configured, All of the remaining serving cells except for the cell, or may be set to one or more serving cells. Or the uplink transmission path for the DRBs in which the uplink transmission path between the specific DRB and the specific serving cell is not configured can always be set as the main serving cell.

In addition, as described above, the uplink transmission path setting between the specific DRB and the specific serving cell includes HARQ ACK / NACK information for downlink data, channel status information for downlink (hereinafter referred to as CSI (Channel Status Information) An uplink transmission channel for supporting downlink transmission such as a Quality Indicator (RI), a Rank indicator, a Precoding Matrix indicator (PMI), a Precoding Type Indicator (PTI) information), an ARQ ACK / NACK (RLC Status PDU) It may indicate only the transmission path of the signaling.

As described above, the uplink transmission path setting between the specific DRB and the specific serving cell is performed by using the transmission path of the uplink transmission channel and signaling for supporting the downlink transmission and the transmission path of the uplink data processed through the specific DRB, May be included.

The UE may additionally configure the small cell configured in the small base station as a secondary serving cell based on the RRC connection reconfiguration message, and configure / reconfigure the DRB and the RLC layer of the UE. The MS may transmit an RRC connection reconfiguration completion message to the macro base station in response to the RRC connection reconfiguration message.

The macro base station transmits the RRC Connection Reconfiguration Complete Indication message to the small base station (S1355). The RRC connection reconfiguration completion indication message may indicate a message including an indicator for informing the small base station that the RRC connection reconfiguration procedure of S1350 has been completed. The RRC connection reconfiguration complete indication message may be transmitted to the small base station via the X2 interface. Or when the small base station confirms that the PDCP PDU or the RLC SDU of the macro base station for the extended bearer is received at the small base station, the small base station can consider the same condition as the reception of the above RRC connection reconfiguration complete indication message.

The macro base station forwards the data to the small base station (S1360). The data may be data that the macro base station intends to transmit to the terminal through the extended bearer of the small cell. The macro base station can forward the data to the small base station through the backhaul network. The forwarding of the data may be performed by the RLC entity of the small cell in the PDCP entity of the macro cell. That is, the PDCP PDU or the RLC SDU of the macro cell for the data may be the RLC SDU of the small cell.

The small base station transmits the data to the terminal (S1365). The small base station can transmit the data to the terminal through the extended bearer set in the small cell.

When the macro base station forwards the data to the MS from the macro base station, the macro base station recognizes that the macro base station has completed the setup (configuration change) of the DRB to the MS and can start the procedure for transmitting the forwarded data to the MS. In this case, the step S1355 may be omitted.

Alternatively, the small base station may recognize that the macro base station has completed the setup of the DRB to the mobile station after receiving the RRC connection reconfiguration complete indication message including the indicator informing that the RRC connection reconfiguration procedure is completed from the macro base station, And may start the procedure of transmitting the received data to the terminal. In this case, S1355 is not omitted. Also in this case, S1360 may be performed before S1355.

The MS transmits uplink data of the service for the extended bearer to the small base station (S1370). In this example, the uplink transmission path obtained in step S1350 by the UE indicates a small cell serving as a secondary serving cell.

The uplink data includes, for example, HARQ ACK / NACK information for downlink data received by the MS in step 1365, CSI (CQI, RI, PMI, PTI, etc.) information on the downlink, ARQ ACK / NACK PDU) and the like, and uplink transmission channel and signaling for supporting downlink transmission. Alternatively, the uplink data may include uplink transmission channel and signaling for supporting downlink transmission as described above, and uplink data processed through a specific DRB set up in the terminal.

The UE refers to the information on the uplink transmission path for the corresponding DRB during the DRB setup in step 1350 to transmit the uplink data of the service for the extended bearer and transmits the uplink data to the small cell Through the extended bearer established between the mobile station and the small base station). The uplink transmission path may be indicated by a secondary serving cell index indicated by the ul-transmissionServingCell described in Table 7. [

The small base station forwards the uplink data to the macro base station (S1375). The small base station can forward the uplink data to the macro base station through the backhaul network. The forwarding of the uplink data may be performed by the PDCP entity of the macro cell in the RLC entity of the small cell. That is, the RLC SDU or PDCP PDU of the small cell for the uplink data may be the PDCP PDU of the macro cell.

In such a case, the terminal can simultaneously receive services on the macro cell (main serving cell) configured in the macro base station and the small cell (secondary serving cell) configured in the small base station. Also, in uplink transmission of a UE, uplink data related to a service receiving data through the secondary serving cell can be transmitted through the small cell based on the DRB configuration information for the uplink transmission path have.

FIG. 14 is a flowchart illustrating the operation of the macro base station in the bearer extension procedure according to another example of the present invention.

Referring to FIG. 14, the macro base station receives a measurement report from the terminal (S1400). Here, the macro base station is in a state of being connected to the terminal in the current RRC. That is, the macro base station may be a base station that is currently set up with a terminal and a radio bearer, and the small base station may be a base station that is requested to set up an extended bearer based on a radio bearer between the terminal and the macro base station. The measurement report includes the measurement result for the small cell operated by the small base station. The measurement report includes periodic reporting and event-triggered reporting. It is assumed that the small cell uses a different frequency from the macro cell operated by the macro base station. Measurement reports can be performed through measurement report messages, which may include RSRP and RSRQ values, PCI, CGI, and so on.

The macro base station determines whether to set up an extended bearer based on the measurement report (S1410). For example, when the macro base station does not satisfy or expects that a service requesting a specific QoS is not satisfied among a plurality of services requested by a terminal connected to a macro cell and / , It can be determined to perform the extended bearer setup in order to support the service requesting the corresponding QoS. As another example, when the macro base station needs to control the load level in the macro cell based on the load management policy, it can decide to perform the extended bearer setup to support through the small cell. That is, when the UE can simultaneously service various QoS classes, the macro base station can load balance one of the QoS classes provided in the macro cell to a small cell for load balancing have.

The macro base station can determine whether handover to the small cell or an establishment of an extended bearer in the small cell based on the measurement report and deliver the message to the small base station including the small cell. In the present invention, the description will be limited to the procedure in which the macro base station requests the setting of the extended bearer, that is, the RLC extension, to the small cell included in the small base station.

When it is determined to perform the extended bearer setup, the macro base station generates an RLC extension request message and transmits the RLC extension request message to the small base station (S1420). The macro base station can transmit the RLC extension request message to the small base station via the X2 interface. The RLC extension request message includes user context information including a secondary serving cell index. The secondary serving cell index is an index value of a secondary serving cell to be newly configured for the UE in the small cell. The index value for the newly configured secondary serving cell is managed by the macro base station. The user context information may specifically include information included in Table 6 above.

The macro base station receives the RLC extended response message from the small base station (S1430). The RLC extended response message may be received from the small base station via the X2 interface. The RLC extended response message may include the information in Table 5 above. If the RLC extension response message is an RLC extension grant message, the RLC extension response message may include parameters for the RLC sub-step configured in the extended bearer by the small base station. That is, it may include parameters for the RLC entity, the MAC entity, and the PHY layer.

When the macro BS receives the RLC Extension Accept message from the small base station, the macro base station corresponds to the extended bearer and performs RLC entity reset for the DRB configured in the macro cell The process proceeds (S1440). For example, when the RLC entity for the corresponding DRB of the macro cell is a TM RLC entity, all RLC SDUs are discarded. As another example, when the RLC entity for the corresponding DRB of the macro cell is a UM RLC entity, all possible UMD PDUs configurable as RLC SDUs are configured as RLC SDUs, transmitted to an upper layer (PDCP) PDUs are discarded. As another example, when the RLC entity for the corresponding DRB of the macro cell is an AM RLC entity, RLC SDUs are configured from the byte segments of all possible AMD PDUs configurable as RLC SDUs, and the remaining AMD PDUs And byte segments. And discards all RLC SDUs and AMD PDUs in the transmission. It also discards the RLC control PDUs.

When a procedure for resetting the RLC entity for the corresponding DRB configured in the macro cell proceeds, all the timers related to the RLC entity can be stopped or reset. In addition, all the RLC entity related state variables may be reset to their initial values.

The macro base station generates an RRC connection reconfiguration message and transmits the RRC connection reconfiguration message to the terminal (S1450). The macro base station generates an RRC connection reconfiguration message based on the parameters for the RLC sub-step of the extended bearer configured by the small base station, and transmits the RRC connection reconfiguration message to the UE. The RRC connection reconfiguration message may include DRB configuration information and secondary serving cell configuration information as well as parameters for the RLC sub-step of the extended bearer. At this time, the DRB configuration information may include information on an uplink transmission path. For example, the uplink transmission path can be indicated as a main serving cell configured in a macro base station or a secondary serving cell configured in a small base station. To this end, the serving cell index or the secondary serving cell index information is included in the transmitted DRB configuration information . In this example, it is assumed that the uplink transmission path indicates a small cell which is a secondary serving cell.

The secondary cell configuration information is information for adding a secondary serving cell. The secondary serving cell configuration information may include the secondary serving cell index which is an index for the small cell to be added to the secondary serving cell. The RRC connection reconfiguration message may include the syntax shown in Table 7 above.

The macro base station receives an RRC connection reconfiguration completion message from the mobile station in response to the RRC connection reconfiguration message (S1460). Thereafter, the macro base station transmits an RRC connection reconfiguration complete indication message to the small base station (S1470). The RRC connection reconfiguration complete indication message may indicate a message including an indication to inform the small base station that the RRC connection reconfiguration procedure is completed. The RRC connection reconfiguration complete message may be transmitted to the small base station via the X2 interface.

The macro base station forwards (downlink) data to the small base station (S1480). The data may be data that the macro base station wants to transmit to the terminal through the small cell (the extended bearer established between the terminal and the small base station). For example, the data may be data for a service that the macro base station does not satisfy or can not satisfy the QoS for the terminal through the macro cell. As another example, if the macro base station needs to control the load level in the macrocell based on the load management policy or the like, it may be data on a service for offloading to a small cell in order to maintain the load balance.

The macro base station can forward the data to the small base station through the backhaul network. The forwarding of the data may be performed by the RLC entity of the small cell in the PDCP entity of the macro cell. That is, the PDCP PDU or the RLC SDU of the macro cell for the data may be the RLC SDU of the small cell.

The macro base station receives the uplink data from the small base station (S1490). The uplink data may be uplink data for the (downlink) data transmitted from the macro base station to the mobile station through the small cell (extended bearer between the mobile station and the small base station). The uplink data may include information such as HARQ ACK / NACK and an ARQ ACK / NACK (RLC Status PDU), for example. The macro base station can receive the uplink data from the small base station through the backhaul network. The forwarding of the uplink data may be performed by the PDCP entity of the macro cell in the RLC entity of the small cell. That is, the RLC SDU or PDCP PDU of the small cell for the uplink data may be the PDCP PDU of the macro cell.

15 is a flowchart showing the operation of the small base station in the bearer extension procedure according to another example of the present invention.

Referring to FIG. 15, the small base station receives an RLC extension request message from the macro base station (S1500). The macro base station is in the RRC connection state with the terminal. That is, the macro base station may be a base station that is currently set up with a mobile station and a radio bearer, and the small base station may be a base station that is requested to establish an extended bearer based on a radio bearer between the mobile station and the macro base station. It is assumed that the small cell uses a different frequency from the macro cell operated by the macro base station. The small base station can receive the RLC extension request message from the macro base station via the X2 interface. The RLC extension request message includes user context information including a secondary serving cell index. The secondary serving cell index is an index value of a secondary serving cell to be newly configured for the UE in the small cell. The index value for the newly configured secondary serving cell is managed by the macro base station. The user context information may include the information of Table 6 above.

If the RLC Extension Request message is received, the RLC Extension Request message, the RLC Extension Request message, the RLC Extension Request message, the RLC sub-RLC entity, the MAC entity, and the PHY Layer is configured / reconstructed (S1510). The extended bearer includes a DRB. For example, if the small base station has decided to perform the extended bearer setup, a new DRB can be additionally configured in the small cell. The DRB may have the same EPS ID value and QoS characteristic as the DRB configured in the macro cell (i.e., main serving cell) currently configured in the macro base station. The DRB may be configured based on configuration information for the RLC layer. The MAC and PHY layers may be configured based on the configuration information for the small cell.

If the small base station determines not to perform the extended bearer setup, step S1510 may be omitted.

The small base station generates an RLC extended response message and transmits the RLC extended response message to the macro base station (S1520). The RLC extended response message may be transmitted to the macro base station via the X2 interface. The RLC extension response message may include parameters related to the RLC lower layer configured in the extended bearer of the small base station. The RLC extended response message may include the information in Table 5 above.

The small base station receives the RRC connection reconfiguration completion indication message from the macro base station (S1530). The RRC connection reconfiguration complete indication message indicates a message including an indicator for informing the small base station that the macro base station has completed the RRC connection reconfiguration procedure for the UE based on the parameters for the RLC sub-stage of the extended bearer . The RRC connection reconfiguration complete indication message may be transmitted to the small base station via the X2 interface.

The small base station receives forwarding data (downlink) from the macro base station (S1540). The data may be data that the macro base station intends to transmit to the terminal through the extended bearer of the small cell. For example, the data may be data for a service that does not satisfy or can not meet a specific QoS in the macro cell of the macro base station. As another example, if the macro base station needs to control the load level in the macrocell based on the load management policy or the like, it may be data on a service for offloading to a small cell in order to maintain the load balance.

The small base station transmits the forwarded data to the terminal (S1550). The small base station can transmit the data to the terminal through the extended bearer set in the small cell.

When the macro base station forwards the data to the MS from the macro base station, the macro base station recognizes that the macro base station has completed the setup (configuration change) of the DRB to the MS and can start the procedure for transmitting the forwarded data to the MS. In this case, the step S1530 may be omitted.

Alternatively, the small base station may recognize that the macro base station has completed the setup of the DRB to the mobile station after receiving the RRC connection reconfiguration complete indication message including the indicator informing that the RRC connection reconfiguration procedure is completed from the macro base station, And may start the procedure of transmitting the received data to the terminal. In this case, S1530 is not omitted. Also in this case, S1540 may be performed before S1530.

The small base station receives the uplink data of the service for the extended bearer from the mobile station (S1560). That is, the uplink data may be uplink data for the (downlink) data transmitted by the small base station to the mobile station through the extended bearer of the small cell. In this case, the small base station can receive the uplink data through the small cell. The uplink data includes, for example, HARQ ACK / NACK information for downlink data transmitted to the UE in step S1550, CSI (CQI, RI, PMI, PTI, etc.) information for downlink, ARQ ACK / NACK RLC Status PDU) and the like, and uplink transmission channel and signaling for supporting downlink transmission. Alternatively, the uplink data may include an uplink transport channel and signaling for supporting downlink transmission through an extended bearer, and uplink data processed through a specific DRB set up in the terminal.

The small base station forwards the uplink data to the macro base station (S1570). The small base station can forward the uplink data to the macro base station through the backhaul network. The forwarding of the uplink data may be performed by the PDCP entity of the macro cell in the RLC entity of the small cell. That is, the RLC SDU or PDCP PDU of the small cell for the uplink data may be the PDCP PDU of the macro cell.

16 is a flowchart illustrating operations of a UE in a bearer extension procedure according to the present invention.

Referring to FIG. 16, the UE performs measurement report to the macro base station (S1600). Here, the macro base station is in the RRC connection state with the terminal. That is, the macro base station may be a base station that is currently set up with a terminal and a radio bearer, and the small base station may be a base station that is requested to set up an extended bearer based on a radio bearer between the terminal and the macro base station. The measurement report includes measurement results for neighboring cells, particularly small cells. The measurement report includes periodic reporting and event-triggered reporting. It is assumed that the small cell uses a different frequency from the macro cell operated by the macro base station. The measurement report may be performed through a measurement report message, which may include RSRP and RSRQ values, PCI, CGI, and the like.

The MS receives the RRC connection reconfiguration message from the macro base station (S1610). The RRC connection reconfiguration message may include parameters for the RLC sub-step of the small cell's extended bearer. The RRC connection reconfiguration message may include DRB configuration information and secondary serving cell configuration information as well as parameters for the RLC sub-step of the extended bearer. At this time, the DRB configuration information may include information on an uplink transmission path. For example, the uplink transmission path can be indicated as a main serving cell configured in a macro base station or a secondary serving cell configured in a small base station. To this end, the serving cell index or the secondary serving cell index information is included in the transmitted DRB configuration information . That is, in this case, the uplink data of the service for the DRB of the UE can be transmitted through the serving cell index or the secondary serving cell index indicated by the secondary serving cell index. If at least one uplink transmission path between a specific DRB and a specific serving cell is set as described above, an uplink transmission path for DRBs for which uplink transmission paths between a specific DRB and a specific serving cell are not configured, All of the remaining serving cells except for the cell, or may be set to one or more serving cells. Or the uplink transmission path for the DRBs in which the uplink transmission path between the specific DRB and the specific serving cell is not configured can always be set as the main serving cell.

The secondary cell configuration information is information for adding a secondary serving cell. The secondary serving cell configuration information may include the secondary serving cell index which is an index for the small cell to be added to the secondary serving cell. The RRC connection reconfiguration message may include the syntax shown in Table 7.

The UE may configure (add) the small cell configured in the small base station as a secondary serving cell based on the RRC connection reconfiguration message and configure / reconfigure the DRB and the RLC layer of the UE in step S1620. The MS may transmit an RRC connection reconfiguration completion message to the macro base station in response to the RRC connection reconfiguration message (S1630).

The terminal receives (downlink) data from the small base station (S1640). The terminal receives the data from the small base station through the small cell (specifically, the extended bearer set in the small cell). The data may be data that the macro base station intends to transmit to the terminal through the extended bearer of the small cell. For example, the data may be data forwarded to the small base station when the macro base station is predicted to fail or fail to meet the QoS required by the service for the data. Since the radio resource allocation opportunity and the resource allocation amount through the small cell are generally larger or larger than the macro cell, even if the macro cell does not satisfy the specific QoS, Can be provided from the small base station. As another example, the data may be data forwarded to the small base station so as to be supported through the small cell when the macro base station needs to control the load level in the macrocell based on the load management policy or the like.

The MS transmits uplink data of the service for the extended bearer to the small base station (S1650). That is, the uplink data may be uplink data for the (downlink) data transmitted by the small base station to the mobile station through the extended bearer of the small cell. In this case, the small base station can receive the uplink data through the extended bearer. The uplink data includes, for example, HARQ ACK / NACK information for downlink data received by the UE in step 1640, CSI (CQI, RI, PMI, PTI, etc.) information for the downlink, ARQ ACK / NACK RLC Status PDU) and the like, and uplink transmission channel and signaling for supporting downlink transmission. Alternatively, the uplink data may include uplink transmission channel and signaling for supporting downlink transmission as described above, and uplink data processed through a specific DRB set up in the terminal.

In step S1620, the UE refers to the information on the uplink transmission path for the corresponding DRB during the DRB setup to transmit the uplink data of the service for the DRB, and transmits the uplink data to the small cell And the extended bearer set between the base station and the small base station). For example, the uplink transmission path can be indicated as a main serving cell configured in the macro base station or a secondary serving cell configured in the small base station. For this purpose, the serving cell index or the secondary serving cell index information may be included in the DRB configuration information . In this example, the uplink transmission path indicates a small cell serving as a secondary serving cell. The uplink transmission path may be indicated by a serving cell index or a secondary serving cell index indicated by the ul-transmissionServingCell described in Table 7. [

17 is a block diagram of a terminal, a macro base station, and a small base station according to the present invention.

Referring to FIG. 17, a terminal 1700 includes a terminal processor 1705, a terminal receiver 1710, and a terminal transmitter 1715. The terminal processor 1705 measures a signal received from a serving cell, that is, a macro cell and a small cell which is a neighboring cell, and generates a measurement report. The measurement report includes information on the strength or quality of the signal received by the terminal 1700 from the neighbor cell as well as the macro cell. In the present invention, the measurement report can be used as a scale for judging the necessity of setting up the extended bearer.

The terminal receiving unit 1710 receives the RRC connection reconfiguration message from the macro base station 1730. The terminal processor 1705 interprets the RRC connection reconfiguration message received from the macro base station 1730, reconstructs the RRC connection based on the RRC connection reconfiguration message, and generates the RRC connection reconfiguration complete message upon completion of the RRC connection reconfiguration. For example, the terminal processor 1705 can interpret the syntax as shown in Table 7 and configure / reconfigure related parameters.

Based on the RRC connection reconfiguration message, the terminal processor 1710 can perform DRB setup and RLC sub-step configuration / reconfiguration at the terminal for the extended bearer setup at the UE, Cell configuration may be performed.

Specifically, the terminal processor 1710 may configure / reconfigure RLC sub-steps based on the RRC connection reconfiguration message. In addition, the terminal processor 1710 may configure the small cell as a secondary serving cell based on the RRC connection reconfiguration message. Also, the terminal processor 1710 transmits the RLC connection reconfiguration message to the mobile station based on the uplink transmission path information included in the RRC connection reconfiguration message, for the downlink data received through the small cell (specifically, the extended bearer established between the mobile station and the small base station) And related parameters may be configured to transmit the uplink data through the small cell.

The terminal processor 1710 analyzes the information on the uplink transmission path in the DRB configuration information included in the RRC connection reconfiguration message and transmits the information to the small cell (specifically, the extended bearer 1760 configured between the terminal 1700 and the small base station 1760) Through the macro cell or the small cell to the uplink data on the data received by the terminal reception unit 1710 through the macro cell or the small cell. For example, the uplink transmission path may be indicated as a primary serving cell configured in the macro base station or a secondary serving cell configured in the small base station. To this end, the serving cell index or the secondary serving cell index information may be included in the DRB configuration information have. This can be indicated by a serving cell index or a secondary serving cell index indicated by the ul-transmissionServingCell described in Table 7. [ The terminal processor 1710 can analyze the serving cell index or the secondary serving cell index indicated by the ul-transmissionServingCell, and set the uplink transmission path.

When at least one uplink transmission path between a specific DRB and a specific serving cell is set as described above, the terminal processor 1710 transmits uplinks to DRBs for which uplink transmission paths between a specific DRB and a specific serving cell are not configured, The transmission path may be set to all of the remaining serving cells except the specific serving cell or may be set to one or more serving cells. Alternatively, the terminal processor 1710 can always set uplink transmission paths for DRBs for which uplink transmission paths between a specific DRB and a specific serving cell are not configured as main serving cells.

The terminal reception unit 1710 receives data from the small base station 1760. In this case, the terminal receiver 1710 can receive the data from the small base station 1760 through a frequency different from a frequency at which the macro base station 1730 transmits signaling and data for the general service. The terminal reception unit 1210 can receive the data from the small base station 1760 through the small cell (specifically, the extended bearer established between the terminal 1700 and the small base station 1760). The data may be data that the macro base station 1730 desires to transmit to the terminal 1700 through the extended bearer. For example, when it is predicted that the macro base station 1730 does not satisfy the service requesting the specific QoS among the plurality of services requested by the terminal 1700 connected to the macro cell, Can be forwarded to the small base station 1760. As another example, if the macro base station 1730 needs to control the load level in the macro cell based on the load management policy or the like, it allocates the data for one of the QoS classes provided in the macro cell to the small cell, the data may be forwarded to the small base station 1760 in order to achieve load balancing.

The terminal processor 1710 generates uplink data corresponding to the data received by the terminal receiver 1710 through the extended bearer. For example, the terminal processor 1710 may transmit HARQ ACK / NACK information for (downlink) data received from the small base station 1760 through the extended bearer by the terminal receiver 1710, CSI (CQI, The uplink data including at least one of uplink transmission channel and signaling for supporting downlink transmission such as RI, PMI, PTI, and the like, ARQ ACK / NACK (RLC Status PDU) The terminal transmission unit 1715 transmits the uplink data to the small base station 1760.

The terminal transmission unit 1715 transmits the measurement report to the macro base station 1730 and transmits the RRC reconfiguration complete message to the macro base station 1730.

The macro base station 1730 includes a macro processor 1735, a macro radio receiver 1740, a macro radio transmitter 1745, a macro wire receiver 1750 and a macro wire transmission unit 1755.

The macro processor 1735 determines whether an extended bearer setting is necessary based on the measurement report received from the terminal 1700. [ For example, the macro processor 1735 may not satisfy or fail to satisfy a service requesting a specific QoS among a plurality of services requested by the terminal 1700 connected to the macro cell, If it is determined that the small cell can provide the service satisfying the specific QoS, it can be determined that the extended bearer setup is necessary. As another example, if the macro base station 1730 needs to control the load level in the macro cell based on the load management policy or the like, the macro base station 1730 may determine to perform the extended bearer setup to support through the small cell. That is, when the UE can simultaneously service various QoS classes, one of the QoS classes provided in the macro cell is offloaded to a small cell for load balancing, It can be determined to perform the setting.

If it is determined that the extended bearer setting is necessary, the macro processor 1735 generates an RLC extension request message. The macro processor 1735 may generate the RLC extension request message including user context information or RLC configuration information. The user context information may include the information of Tables 1 and 2, and the RLC configuration information may include the information of Tables 3 and 4 above. In addition, the macro processor 1235 may generate an RLC extension request message including user context information including a secondary serving cell index. The user context information including the secondary serving cell index may include the information of Table 6 above.

When the macro wired receiver 1250 receives the RLC extension response message indicating the RLC extension acceptance from the small base station 1760, the macro processor 1735 sets the macro cell The RLC entity re-establishment procedure for the DRB corresponding to the extended bearer configured in FIG. For example, the macro processor 1735 discards all RLC SDUs when the RLC entity for the corresponding DRB of the macro cell is a TM RLC entity. As another example, when the RLC entity for the corresponding DRB of the macro cell is a UM RLC entity, the macro processor 1735 constructs all possible UMD PDUs configurable as RLC SDUs into an RLC SDU, And discards the remaining UMD PDUs. As another example, if the RLC entity for the corresponding DRB of the macro cell is an AM RLC entity, the macro processor 1735 constructs an RLC SDU from all possible byte segments of AMD PDUs that can be configured as an RLC SDU, And discards the remaining AMD PDUs and byte segments. In addition, the macro processor 1735 discards all RLC SDUs and AMD PDUs in the macro radio transmission unit 1745. It also discards the RLC control PDUs.

The macro processor 1735 may suspend or reset all the RLC entity related timers when a procedure for resetting the RLC entity for the corresponding DRB configured in the macro cell proceeds. In addition, the macro processor 1735 may reset all state variables associated with the RLC entity to an initial value.

In addition, the macro processor 1735 may generate an RRC connection reconfiguration message for RRC connection reconfiguration based on the RLC extended response message received from the small base station 1760. The RRC connection reconfiguration message may include parameters for the RLC sub-step configured by the small base station 1760. In addition, the RRC connection reconfiguration message may include secondary cell configuration information for configuring the small cell as a secondary serving cell. That is, the macro processor 1735 may include a secondary serving cell configuration information field including contents configuring the small cell as a secondary serving cell in the terminal 1700 in generating the RRC connection reconfiguration message. Also, the RRC connection reconfiguration message may include DRB configuration information. At this time, the DRB configuration information may include information on an uplink transmission path. The uplink transmission path can be indicated as a main serving cell configured in the macro base station or a secondary serving cell configured in the small base station, and the serving cell index or the secondary serving cell index information may be included in the DRB configuration information. For example, the macro processor 1735 may generate an RRC connection reconfiguration message including information indicating the uplink transmission path to a small cell configured in a small base station. In this case, the macro processor 1735 may generate the RRC connection reconfiguration message including the syntax shown in Table 7 above.

When the macro wireless receiver 1740 receives the RRC connection reconfiguration completion message from the terminal 1700, the macro processor 1735 generates an RRC connection reconfiguration completion indication message and transmits the RRC connection reconfiguration completion indication message to the small base station 1755 via the macro wired transmission unit 1755. [ (1760).

In addition, the macro processor 1735 can control to forward the data to the small base station 1760. That is, the macro processor 1735 can transmit the data to the small base station 1760 via the macro wired transmission unit 1755. [ In this case, the macro processor 1735 can control the output of the PDCP entity of the macro cell for the data to be forwarded to the small base station 1760. In this case, the output of the PDCP entity of the macro cell to the data may be an input of the RLC entity of the small cell. That is, the PDCP PDU or the RLC SDU of the macro cell for the data may be the RLC SDU of the small cell.

The macro wireless receiving unit 1740 receives the measurement report from the terminal 1700. The measurement report includes measurement results for neighboring cells, particularly small cells. The measurement report includes periodic reporting and event-triggered reporting. It is assumed that the small cell uses a different frequency from the macro cell operated by the macro base station. The measurement report may be performed through a measurement report message, which may include RSRP and RSRQ values, PCI, CGI, and the like.

In addition, the macro wireless receiving unit 1740 receives the RRC connection reconfiguration completion message from the terminal 1700.

The macro wired line receiving unit 1750 receives the RLC extension response message including whether to accept the extended bearer setting from the small base station 1760. The macro wired receiver 1750 receives the RLC extension response message from the small base station 1760 via the X2 interface. Further, the macro wired receiver 1750 receives the uplink data from the small base station 1760. The uplink data may be (corresponding) uplink data for data to be forwarded from the macro wired receiver 1750 to the small base station 1760. The forwarding of the uplink data may be performed by the PDCP entity of the macro cell in the RLC entity of the small cell. That is, the RLC SDU or PDCP PDU of the small cell for the uplink data may be the PDCP PDU of the macro cell.

The macro wireless transmission unit 1745 transmits an RRC connection reconfiguration message to the terminal 1700.

The macro wired transmission unit 1755 transmits the RLC extension request message to the small base station 1760. In addition, the macro wired transmission unit 1755 may transmit the RRC connection reconfiguration complete indication message to the small base station 1760. The macro wired transmission unit 1755 transmits the RLC extension request message to the small base station 1760 via the X2 interface. The macro wired transmission unit 1755 can transmit an RRC connection reconfiguration complete indication message to the small base station 1760 via the X2 interface.

In addition, the macro wired transmission unit 1755 forwards the (downlink) data to the small base station 1760. The macro wire transmission unit 1755 can forward the data to the small base station 1760 through the backhaul network.

The small base station 1760 includes a small processor 1765, a small wireless transmitting unit 1770, a small wireless receiving unit 1775, a small wire receiving unit 1785 and a small wire transmitting unit 1780.

The small processor 1765 performs permission control for the RLC extension request of the macro base station 1730, that is, the request for setting up an extended bearer. When the small processor 1765 decides to perform the extended bearer setup based on the RLC extension request message transmitted by the macro base station 1730, the small processor 1765 transmits, based on the user context information or RLC configuration information included in the RLC extension request message, And configures / reconfigures the RLC layer and the following stages. Hereinafter, an RLC layer or lower layer includes an RLC entity, a MAC entity, and a PHY layer. The extended bearer includes a DRB. For example, if the small processor 1765 has decided to perform the extended bearer setup, a new DRB may be additionally configured in the small cell. The small processor 1765 may configure the DRB to have the same EPS ID value and QoS characteristic as the DRB configured in the macro cell (i.e., main serving cell) currently configured in the macro base station.

For example, the small processor 1765 may use the E-RAB already configured in the small cell. The macro cell configured in the macro base station 1730 and the small cell configured in the small base station 1760 are configured to have QoS for each E-RAB based on an E-RAB setup configured in the MME. Therefore, based on the QoS (or QCI) in the E-RAB configured to support the UE in the current macro cell, the small base station can provide the corresponding service using the E-RAB configured in the small cell You can check whether there is. The small processor 1765 confirms whether the E-RAB configured in the small cell satisfies the QoS (or QCI) in the E-RAB configured to support the service in the current macrocell, or the like . In this case, the small processor 1765 checks whether the service can be provided using the E-RAB configured in the small cell based on the user situation information, and if the service can be provided, RAB < / RTI > corresponding to the E-RAB in question.

As another example, the small processor 1765 may not have an E-RAB configured in a small cell or may not use an E-RAB that is already configured. In this case, the small processor 1765 can further configure a new E-RAB (or DRB) in the small cell. In this case, based on the QoS for the E-RAB of the macro cell or the RLC configuration information, the small processor 1765 can configure the RLC entity in the small cell. At this time, there is no configuration for the upper end of the RLC entity for the DRB newly configured in the small cell, that is, the PDCP entity, or the like, or it may be configured in a default state. In configuring the RLC sub-entity, the small processor 1765 may be based on the user context information included in the RLC extension request message. Or the small processor 1765 directly obtains the RLC configuration information through the RLC extension request message and configures / reconfigures the RLC entity. In addition, the small processor 1765 may acquire MAC configuration information and PHY configuration information for the entity and configure / reconfigure the MAC entity and the PHY layer based on the RLC configuration information.

In addition, the small processor 1765 generates an RLC extended response message indicating whether or not the extended bearer setting is accepted. The RLC extension response message may include parameters for the RLC sub-step configured in the small base station. The RLC extended response message may include the information in Table 5 above.

In addition, the small processor 1765 can control the data that the small wire receiving unit 1785 forwarded to be the input of the RLC entity of the small cell. In this case, the PDCP PDU or the RLC SDU of the macro cell for the data may be the RLC SDU of the small cell.

Also, the small processor 1765 can control the uplink data forwarded to the macro base station 1730 by the small wired transmission unit 1780 to be the output of the RLC entity of the small cell. In this case, the RLC SDU or PDCP PDU of the small cell for the data may be the PDCP PDU of the macro cell.

The small processor 1765 processes the data through the RLC entity, the MAC entity, and the PHY layer, and transmits the data to the terminal 1700 through the small wireless transmission unit 1770.

The small wire receiving unit 1785 receives the RLC extension request message from the macro base station 1730. The small wire receiving unit 1785 can receive an RRC connection reconfiguration complete indication message from the macro base station 1730. [ The small wire receiving unit 1785 can receive the RLC extension request message and the RRC connection reconfiguration complete indication message from the macro base station 1730 through the X2 interface.

Further, the small wire receiving section 1785 receives (forward) data from the macro base station 1730 (downlink). The small wire receiving unit 1785 can receive the data from the macro base station 1730 through the backhaul network. At this time, the output of the PDCP entity of the macro cell to the data may be an input of the RLC entity of the small cell. That is, the PDCP PDU or the RLC SDU of the macro cell for the data may be the RLC SDU of the small cell.

The small processor 1765 can transmit the forwarded data to the terminal 1700 through the small wireless transmission unit 1770 when the small wire receiving unit 1785 receives the forwarding data from the macro base station 1730 have. Alternatively, the small processor 1765 may transmit the RRC connection reconfiguration completion indication message to the macro base station 1730 only after the small wire reception unit 1785 receives the RRC connection reconfiguration completion indication message including the indicator indicating that the RRC connection reconfiguration procedure is completed To the terminal 1700 through the small wireless transmission unit 1770. [

The small wired transmission unit 1780 transmits an RLC extension response message to the macro base station 1730. The small wired transmission unit 1780 may transmit the RLC extended response message to the macro base station 1730 via the X2 interface.

In addition, the small wireless transmitting unit 1770 transmits the forwarded data from the macro base station 1730 to the terminal 1700. The small wireless transmitting unit 1770 can transmit the data to the terminal 1700 using a different frequency from the macro wireless transmitting unit 1745. [

Also, the small wireless receiving unit 1775 receives the uplink data from the terminal 1700. [ The uplink data may be uplink data corresponding to data transmitted from the small wire receiving unit 1785 to the terminal 1700 through the small wireless transmitting unit 1770. In this case, the small base station can receive the uplink data through the small cell. The uplink data includes, for example, HARQ ACK / NACK information for data (downlink) transmitted to the mobile station by the small radio transmitter 1770, CQI, RI, PMI, PTI , An ARQ ACK / NACK (RLC Status PDU), and the like, and an uplink transport channel and signaling for supporting downlink transmission. Alternatively, the uplink data may include uplink transmission channel and signaling for supporting downlink transmission, and uplink data processed through the specific DRB set up in the AT 1700. [

In addition, the small wired transmission unit 1780 forwards the uplink data received from the terminal 1700 to the macro base station 1730. In this case, the uplink output of the RLC entity of the small cell for the uplink data may be input to the PDCP entity of the macro cell. That is, the RLC SDU or PDCP PDU of the small cell for the uplink data may be the PDCP PDU of the macro cell.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas falling within the scope of the same shall be construed as falling within the scope of the present invention.

Claims

A macro base station (macro eNB) supporting an extension bearer setup in a heterogeneous network system,
A macro wireless receiver for receiving a measurement report from a terminal;
Based on the measurement report, an extended bearer setting based on a radio link control (RLC) stage for a small cell using a frequency different from a frequency used by a macro cell is requested A macro processor for generating an RLC extension request message;
A macro wired transmission unit transmitting the RLC extension request message to a small eNB; And
And a macro wired receiver for receiving, from the small base station, an RLC extension response message indicating whether to accept the extended bearer setting in the small cell of the small base station in response to the RLC extension request message. .

The method according to claim 1,
The macro processor generates the RLC extension request message including user context information,
The user status information includes a C-RNTI (Cell Radio Network Temporary Identifier), an EPS Bearer ID, a QoS Class ID, a Data Radio Bearer (DRB) ID, a UE- And GBR (Guaranteed Bit Rate) QoS information. Macro base station.

The method according to claim 1,
Wherein the macro processor generates the RLC extension request message including a C-RNTI, an EPS bearer ID, a DRB ID, and an RLC parameter. Macro base station.

The method according to claim 1,
The macro processor generates the RLC extension request message including user context information,
Wherein the user context information includes at least one of a C-RNTI, an EPS bearer ID, and a QCI, and includes DRB ID, GBR QoS information, and a secondary serving cell index. Macro base station.

The method according to claim 1,
The macro wired receiving unit receives the RLC extended response message including at least one of the RLC extension approval status, the C-RNTI, the EPS bearer ID, the DRB ID, the RLC parameter of the small cell, the MAC parameter, and the PHY parameter Featured, macro base station.

5. The method of claim 5,
Wherein the macro processor is configured in a macro base station and performs a re-establishment procedure of an RLC entity for a DRB corresponding to the extended bearer when the RLC extension approval or disapproval indicates acceptance. Base station.

5. The method of claim 5,
Wherein the MAC processor determines whether the RLC extension approval or disapproval acceptance and if the RLC extension response message includes the RLC parameter, the MAC parameter and the PHY parameter of the small cell, the RLC parameter, the MAC parameter, A DRB configuration information of a terminal corresponding to the extended bearer set in the small cell, and a secondary cell configuration information for the small cell,
And the macro radio transmitting unit transmits the generated RRC connection reconfiguration message to the mobile station.

8. The method of claim 7,
Wherein the macro wired transmission unit forwards the downlink data to the small base station,
Wherein the macro processor controls the output of the PDCP entity of the macro cell to the downlink data to be forwarded to the small base station.

9. The method of claim 8,
Wherein the macro wired receiving unit receives forward link data corresponding to the downlink data from the small base station,
Wherein the macro processor controls the uplink data to be forwarded from a PDCP entity of the macro cell.

As a small base station supporting heterogeneous network systems with extended bearer setup,
A small wire receiving unit for receiving an RLC extension request message from the macro base station to request an establishment of an extended bearer based on an RLC unit for a small cell;
A small processor for generating an RLC extension response message on whether or not to accept establishment of an extended bearer based on the RLC extension request message; And
And a small wired transmission unit for transmitting the RLC extension response message to a macro base station.

11. The method of claim 10,
Wherein the small wire receiving unit receives the RLC extension request message including at least one of a C-RNTI, an EPS bearer ID, a QCI, a DRB ID, a terminal dedicated MAC parameter, a GBR QoS information, and a macro cell RLC parameter , Small base station.

11. The method of claim 10,
Wherein the small wire receiving unit receives the RLC extension request message including at least one of a C-RNTI, an EPS bearer ID, a QCI, a DRB ID, a GBR QoS information, and a secondary serving cell index.

12. The method of claim 11,
Wherein the small processor determines the extended bearer setup acceptance based on QoS for an E-RAB (E-RAB) already configured in the small cell.

12. The method of claim 11,
Wherein the small processor further configures a new E-RAB or a DRB when the E-RAB is not configured in the small cell and the extension bearer setup acceptance is determined.

13. The method of claim 12,
The small processor configures a new DRB in the small cell,
Wherein the configured DRB has the same EPS ID value and QoS characteristic as the DRB configured in the macro cell.

11. The method of claim 10,
Wherein the small processor configures / reconfigures the RLC entity, the MAC entity, and the PHY layer for the small cell based on the RLC Extension Request message when it has determined the establishment of the extended bearer setup.

17. The method of claim 16,
Wherein the small processor includes an RLC parameter, a MAC parameter, and a PHY parameter for the configured / reconfigured RLC entity, a MAC entity, and a PHY layer, the RLC entity including the C-RNTI, the EPS bearer ID, Response message to the base station.

18. The method of claim 17,
Further comprising a small radio transmission unit for transmitting downlink data to the mobile station,
The small wire receiving unit forwards the downlink data from the macro base station,
And the small radio transmission unit transmits the downlink data to the mobile station through the small cell.

19. The method of claim 18,
And the small processor controls the downlink data forwarded by the small wire receiving unit to be an input of the RLC entity of the small cell.

19. The method of claim 18,
Further comprising a small radio receiver for receiving uplink data corresponding to the downlink data from the terminal,
And the small wired transmission unit forwards the uplink data to the macro base station.

21. The method of claim 20,
Wherein the macro processor controls the uplink data forwarded by the small wired transmitting unit to the macro base station to be the output of the RLC entity of the small cell.

In a heterogeneous network system, a terminal transmits / receives data through an extended bearer,
Performing a measurement report with a macro base station;
Receiving from the macro base station an RRC connection reconfiguration message including at least one of parameters for an RLC sub-step of a small cell, DRB configuration information for an extended bearer, and secondary cell configuration information for the small cell;
DRB setup and the small cell into a secondary serving cell and configuring / reconfiguring the RLC sub-stage of the UE;
Transmitting an RRC connection reconfiguration complete message to the macro base station; And
And receiving the downlink data from the small base station through the small cell configured as the secondary serving cell.

23. The method of claim 22,
Wherein the small cell uses a frequency band different from a frequency used by the macrocell.

23. The method of claim 22,
Setting an uplink transmission path to a small cell based on the DRB configuration information included in the RRC connection reconfiguration message;
And transmitting the uplink data corresponding to the downlink data to the small base station through the small cell.

In a heterogeneous network system, a macro base station supports extended bearer setup,
Receiving a measurement report from the terminal;
Generating an RLC extension request message for requesting an establishment of an extended bearer based on the RLC stage for the small cell based on the measurement report;
Transmitting the RLC extension request message to the small base station; And
And receiving, from the small base station, an RLC extension response message indicating whether to accept the extended bearer setup in the small cell of the small base station in response to the RLC extension request message. Way.

In a heterogeneous network system, a small base station supports extended bearer setup,
Receiving an RLC extension request message from the macro base station to request an establishment of an extended bearer based on an RLC layer for a small cell;
Determining an extended bearer setup based on the RLC extension request message and configuring / reconfiguring the RLC sub-stage;
Generating an RLC extended response message including parameters for the configured / reconfigured RLC subchannel; And
And transmitting the RLC extended response message to the macro base station.