WO2015105310A1 - Method for receiving reference signal for small cell discovery, and apparatus therefor - Google Patents

Abstract

The present invention relates to a method for transmitting and receiving a reference signal for small cell discovery and, more specifically, to a method for setting a downlink reference signal in order for a terminal to search for an inactive small cell base station. In particular, the present invention provides a method and an apparatus for receiving, by a terminal, a reference signal for small cell discovery, the method comprising the steps of: receiving a reference signal transmitted by an inactive base station; and checking the reference signal using transmission antenna port information and radio resource allocation information of the reference signal.

Description

Method and apparatus for receiving reference signal for small cell discovery

The present invention relates to a method of transmitting and receiving a reference signal for small cell discovery. More specifically, the present invention relates to a method for setting a downlink reference signal for searching for a small cell base station in an inactive state.

As communication systems have evolved, consumers, such as businesses and individuals, have used a wide variety of wireless terminals. Mobile communication systems such as LTE (Long Term Evolution) and LTE-Advanced of the current 3GPP series are high-speed and large-capacity communication systems that can transmit and receive various data such as video and wireless data out of voice-oriented services. The development of technology capable of transferring large amounts of data is required. Meanwhile, as deployments such as a plurality of cells or small cells are introduced, there is a need for a technique and a method for enabling carrier aggregation to be applicable in various deployment scenarios.

On the other hand, with the increase in wireless terminals and the increase in the transmission and reception data, the communication system needs to process a large amount of data. Accordingly, various types of base stations for data processing have been developed, and the increase of these base stations or data transmission / reception points causes an increase in power consumption of the entire communication system. In addition, when a plurality of base stations are located in a dense environment in order to process a large amount of data, radio signals transmitted and received by each base station are increased, thereby increasing signal interference, thereby reducing data processing speed.

The present invention devised in accordance with the above-described demands proposes a method and apparatus for transmitting and receiving a reference signal of a base station performing an on / off operation in a small cell deployment environment in which macro cells and small cells overlap.

The present invention also proposes a method and apparatus for setting an antenna port and a radio resource for transmitting a reference signal for small cell discovery by a base station in an inactive (off) state.

In addition, the present invention is to propose a method and apparatus for transmitting and receiving a reference signal for small cell discovery for minimizing signal interference in a small cell deployment situation.

According to an aspect of the present invention, there is provided a method for a UE to receive a reference signal for small cell discovery, the method comprising: receiving a reference signal transmitted by a base station in an inactive state and transmitting antenna port information and radio resources of the reference signal; It provides a method comprising the step of identifying a reference signal using the allocation information.

The present invention also provides a method for transmitting a reference signal for small cell discovery by a base station, comprising: configuring a base station in an inactive state, generating a reference signal by setting transmission antenna port information and radio resource allocation information, and transmitting the reference signal. A method comprising transmitting a reference signal using antenna port information and radio resource allocation information is provided.

In addition, the present invention is a terminal for receiving a reference signal for small cell discovery, the receiving unit for receiving the reference signal transmitted by the base station in the inactive state and the reference signal using the transmission antenna port information and radio resource allocation information of the reference signal It provides a terminal device including a control unit for confirming.

In addition, the present invention provides a base station for transmitting a reference signal for small cell discovery, the base station is configured to be in an inactive state, the control unit and the transmit antenna port information for generating a reference signal by setting the transmission antenna port information and radio resource allocation information And a transmitter for transmitting a reference signal using radio resource allocation information.

The present invention described above provides an effect of reducing signal interference by changing a base station providing a small cell to an inactive state in an environment in which macro cells and small cells overlap.

In addition, the present invention has the effect of providing a specific procedure and method for the terminal to receive and confirm the reference signal transmitted by the base station in an inactive state.

In addition, the present invention, the terminal receives the reference signal to measure the channel state of the base station in the inactive state, and based on this connection to the base station in the inactive state by reducing the power consumption and signal interference of the communication system and a large amount of data Provides a processable effect.

1 is a diagram illustrating small cell deployment according to an embodiment.

2 is a diagram illustrating a small cell deployment scenario.

3 to 6 show detailed scenarios in small cell deployment.

7 is a diagram illustrating an example of radio resource allocation of a downlink reference signal.

8 is a diagram illustrating an example of an information element of measurement configuration information.

9 is a diagram illustrating an example of an information element of an RRCConnectionReconfiguration message with higher layer signaling according to the present invention.

FIG. 10 is a diagram illustrating an example of an information element of higher layer signaling including configuration information for CSI-RS transmission.

FIG. 11 is a diagram illustrating another example of an information element of higher layer signaling including configuration information for CSI-RS transmission.

12 illustrates a CSI-RS transmit antenna port table according to an embodiment of the present invention.

FIG. 13 is a diagram illustrating a CSI-RS transmit antenna port table according to the number of transmit antenna ports according to another embodiment of the present invention.

14 is a diagram illustrating an example of a radio resource configuration table for CSI-RS transmission for each frame structure type in the case of a normal cyclic prefix.

15 is a diagram illustrating an example of a radio resource configuration table for CSI-RS transmission for each frame structure type in the case of an extended cyclic prefix.

16 is a view for explaining the operation of the terminal according to another embodiment of the present invention.

17 is a view for explaining the operation of a base station according to another embodiment of the present invention.

18 is a view showing the configuration of a user terminal according to another embodiment of the present invention.

19 is a diagram illustrating a configuration of a base station according to another embodiment of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail through exemplary drawings. In adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are assigned to the same components as much as possible even though they are shown in different drawings. In addition, in describing the present invention, when it is determined that the detailed description of the related well-known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

The wireless communication system in the present invention is widely deployed to provide various communication services such as voice, packet data, and the like. The wireless communication system includes a user equipment (UE) and a base station (base station, BS, or eNB). In the present specification, a user terminal is a generic concept meaning a terminal in wireless communication. In addition, user equipment (UE) in WCDMA, LTE, and HSPA, as well as mobile station (MS) in GSM, user terminal (UT), and SS It should be interpreted as a concept that includes a subscriber station, a wireless device, and the like.

A base station or a cell generally refers to a station that communicates with a user terminal, and includes a Node-B, an evolved Node-B, an Sector, a Site, and a BTS. Other terms such as a base transceiver system, an access point, a relay node, a remote radio head (RRH), a radio unit (RU), and a small cell may be called.

In other words, in the present specification, a base station or a cell is a generic meaning indicating some areas or functions covered by a base station controller (BSC) in CDMA, a Node-B in WCDMA, an eNB or a sector (site) in LTE, and the like. It should be interpreted as, and it is meant to cover all the various coverage areas such as megacell, macrocell, microcell, picocell, femtocell and relay node, RRH, RU, small cell communication range.

Since the various cells listed above have a base station for controlling each cell, the base station may be interpreted in two senses. i) the device providing the megacell, the macrocell, the microcell, the picocell, the femtocell, the small cell in relation to the wireless area, or ii) the wireless area itself. In i) all devices which provide a given wireless area are controlled by the same entity or interact with each other to cooperatively configure the wireless area to direct the base station. The eNB, RRH, antenna, RU, LPN, point, transmit / receive point, transmit point, receive point, and the like, according to the configuration of the radio region, become an embodiment of the base station. In ii), the base station may indicate the radio area itself to receive or transmit a signal from a viewpoint of a user terminal or a neighboring base station.

Therefore, megacells, macrocells, microcells, picocells, femtocells, small cells, RRHs, antennas, RUs, low power nodes (LPNs), points, eNBs, transmit / receive points, transmit points, and receive points are collectively referred to as base stations. do.

In the present specification, the user terminal and the base station are two transmitting and receiving entities used to implement the technology or technical idea described in this specification in a comprehensive sense and are not limited by the terms or words specifically referred to. The user terminal and the base station are two types of uplink or downlink transmitting / receiving subjects used to implement the technology or the technical idea described in the present invention, and are used in a generic sense and are not limited by the terms or words specifically referred to. Here, the uplink (Uplink, UL, or uplink) refers to a method for transmitting and receiving data to the base station by the user terminal, the downlink (Downlink, DL, or downlink) means to transmit and receive data to the user terminal by the base station It means the way.

There is no limitation on the multiple access scheme applied to the wireless communication system. Various multiple access techniques such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), OFDM-FDMA, OFDM-TDMA, OFDM-CDMA Can be used. One embodiment of the present invention can be applied to resource allocation in the fields of asynchronous wireless communication evolving to LTE and LTE-Advanced through GSM, WCDMA, HSPA, and synchronous wireless communication evolving to CDMA, CDMA-2000 and UMB. The present invention should not be construed as being limited or limited to a specific wireless communication field, but should be construed as including all technical fields to which the spirit of the present invention can be applied.

The uplink transmission and the downlink transmission may use a time division duplex (TDD) scheme that is transmitted using different times, or may use a frequency division duplex (FDD) scheme that is transmitted using different frequencies.

In addition, in systems such as LTE and LTE-Advanced, a standard is configured by configuring uplink and downlink based on one carrier or a pair of carriers. The uplink and the downlink include a Physical Downlink Control CHannel (PDCCH), a Physical Control Format Indicator CHannel (PCFICH), a Physical Hybrid ARQ Indicator CHannel (PHICH), a Physical Uplink Control CHannel (PUCCH), an Enhanced Physical Downlink Control CHannel (EPDCCH), and the like. Control information is transmitted through the same control channel, and data is configured by a data channel such as a physical downlink shared channel (PDSCH) and a physical uplink shared channel (PUSCH).

On the other hand, control information may also be transmitted using an enhanced PDCCH (EPDCCH or extended PDCCH).

In the present specification, a cell means a component carrier having a coverage of a signal transmitted from a transmission / reception point or a signal transmitted from a transmission point or a transmission / reception point, and the transmission / reception point itself. Can be.

A wireless communication system to which embodiments are applied may be a coordinated multi-point transmission / reception system (CoMP system) or a coordinated multi-antenna transmission scheme in which two or more transmission / reception points cooperate to transmit a signal. antenna transmission system), a cooperative multi-cell communication system. The CoMP system may include at least two multiple transmission / reception points and terminals.

The multiple transmit / receive point is at least one having a base station or a macro cell (hereinafter referred to as an eNB) and a high transmission power or a low transmission power in a macro cell region, which is wired controlled by an optical cable or an optical fiber to the eNB. May be RRH.

In the following, downlink refers to a communication or communication path from a multiple transmission / reception point to a terminal, and uplink refers to a communication or communication path from a terminal to multiple transmission / reception points. In downlink, a transmitter may be part of multiple transmission / reception points, and a receiver may be part of a terminal. In uplink, a transmitter may be part of a terminal, and a receiver may be part of multiple transmission / reception points.

Hereinafter, a situation in which a signal is transmitted and received through a channel such as a PUCCH, a PUSCH, a PDCCH, an EPDCCH, and a PDSCH may be expressed in the form of 'sending and receiving a PUCCH, a PUSCH, a PDCCH, an EPDCCH, and a PDSCH.'

In addition, hereinafter, a description of transmitting or receiving a PDCCH or transmitting or receiving a signal through the PDCCH may be used as a meaning including transmitting or receiving an EPDCCH or transmitting or receiving a signal through the EPDCCH.

That is, the physical downlink control channel described below may mean PDCCH or EPDCCH, and may also be used to include both PDCCH and EPDCCH.

In addition, for convenience of description, the EPDCCH, which is an embodiment of the present invention, may be applied to the portion described as the PDCCH, and the EPDCCH may be applied to the portion described as the EPDCCH as an embodiment of the present invention.

Meanwhile, high layer signaling described below includes RRC signaling for transmitting RRC information including an RRC parameter.

The eNB performs downlink transmission to the terminals. The eNB includes downlink control information and an uplink data channel (eg, a physical downlink shared channel (PDSCH), which is a primary physical channel for unicast transmission, and scheduling required to receive the PDSCH. For example, a physical downlink control channel (PDCCH) for transmitting scheduling grant information for transmission on a physical uplink shared channel (PUSCH) may be transmitted. Hereinafter, the transmission and reception of signals through each channel will be described in the form of transmission and reception of the corresponding channel.

In the present specification, the macro cell and the small cell are classified by the relative size of the coverage of the communicable cell, and the macro cell has a wider coverage than the small cell. In addition, the macro cell and the small cell may be formed by each base station or transmission and reception point, and in this specification, a base station providing a macro cell is described as a macro cell base station or a master base station or a MeNB, and a base station providing a small cell It may be described as a small cell base station or a secondary base station or SeNB. In addition, in the present specification, a base station changing a state into an activated (ON) and inactive (OFF) state is assumed to be a base station providing a small cell, but is not limited thereto.

The present invention proposes a method for configuring a downlink reference signal for detecting a cell formed by an arbitrary base station (eNB or RRH or RU) in a 3GPP LTE or LTE-Advanced wireless mobile communication system. . In particular, as a method for reducing power consumption of a base station (eNB or RRH or RU) and reducing interference with neighboring cells, the cell is turned on or deactivated according to the number of UEs or the amount of data traffic. A case of supporting a semi-static or dynamic cell on / off mechanism for turning off will be described. To this end, when CSI-RS is newly used as a downlink reference signal for cell discovery in addition to the existing PSS / SSS and CRS, a method of transmitting CSI-RS for cell discovery is proposed.

In this regard, in the present invention, in particular, semi-static or dynamic small cell on in various types of small cell base stations (eNB or RRH or RU) overlapping with macro cells. A method of setting a small cell detection / discovery reference signal according to an application of dynamic small cell on / off will be described. However, it is apparent that the present invention can be applied to various sizes and various types of cells as well as small cells.

In 3GPP LTE or LTE-Advanced system, various CoMP (Coordinated MultiPoint) between macro cell formed by high power eNB and small cell formed by low power remote radio head (low power RRH) connected by optical cable to high power base station Various techniques for the application of the technology can be defined. In addition, a heterogeneous network scenario in which a pico cell or a micro cell for supporting a hot spot or a coverage hole is overlapped with a macro cell. Various interference control techniques in can be proposed. In addition, research on various communication methods using the above-described small cell is being conducted.

Hereinafter, a small cell deployment scenario to which the present invention is applicable will be described.

1 is a diagram illustrating small cell deployment according to an embodiment.

FIG. 1 illustrates a configuration in which a small cell and a macro cell coexist, and in FIGS. 2 to 3 below, whether macro coverage is present and whether the small cell is for outdoor or indoor. In order to determine whether the small cell is sparse or dense, the deployment of the small cell is divided in more detail according to whether or not to use the same frequency spectrum as the macro in terms of spectrum.

2 is a diagram illustrating a small cell deployment scenario. FIG. 2 shows a typical representative configuration for the scenario of FIG. 3. 2 illustrates a small cell deployment scenario and includes scenarios # 1, # 2a, # 2b and # 3. 200 denotes a macro cell, and 210 and 220 denote small cells. In FIG. 2, the overlapping macro cell may or may not exist. Coordination may be performed between the macro cell 200 and the small cells 210 and 220, and coordination may also be performed between the small cells 210 and 220. The overlapped areas of 200, 210, and 220 may be bundled into clusters.

3 to 6 show detailed scenarios in small cell deployment.

3 shows scenario # 1 in small cell deployment. Scenario 1 is a co-channel deployment scenario of a small cell and a macro cell in the presence of an overhead macro and an outdoor small cell scenario. 310 denotes a case where both the macro cell 311 and the small cell are outdoors, and 312 indicates a small cell cluster. Users are distributed both indoors and outdoors.

Solid lines connecting the small cells in the small cell 312 mean a backhaul link within a cluster. The dotted lines connecting the base station of the macro cell and the small cells in the cluster mean a backhaul link between the small cell and the macro cell.

4 illustrates small cell deployment scenario # 2a. Scenario 2a is an deployment scenario in which the small cell and the macro use different frequency spectrums in the presence of an overlay macro and an outdoor small cell scenario. Both macro cell 411 and small cells are outdoors and 412 indicates a small cell cluster. Users are distributed both indoors and outdoors.

Solid lines connecting the small cells in the small cell 412 mean a backhaul link within a cluster. The dotted lines connecting the base station of the macro cell and the small cells in the cluster mean a backhaul link between the small cell and the macro cell.

5 illustrates small cell deployment scenario # 2b. Scenario 2b is a deployment scenario in which the small cell and the macro use different frequency spectrums in the presence of an overlay macro and an indoor small cell scenario. Macro cell 511 is outdoors, small cells are all indoors, and 512 indicates a small cell cluster. Users are distributed both indoors and outdoors.

Solid lines connecting the small cells in the small cell 512 mean a backhaul link within a cluster. The dotted lines connecting the base station of the macro cell and the small cells in the cluster mean a backhaul link between the small cell and the macro cell.

6 illustrates small cell deployment scenario # 3. Scenario 3 is an indoor small cell scenario in the absence of coverage of macros. 612 indicates a small cell cluster. In addition, small cells are all indoors, and users are distributed both indoors and outdoors.

Solid lines connecting the small cells in the small cell 612 mean a backhaul link within a cluster. The dotted lines connecting the base station of the macro cell and the small cells in the cluster mean a backhaul link between the small cell and the macro cell.

The frequencies F1 and F2 used in the various small cell scenarios of FIGS. 1 and 2 to 6 described above may be frequencies supporting the same duplex mode, or F1 and F2 may have different duplex modes. For example, F1 may be a frequency that supports the FDD mode, F2 may be a frequency that supports the TDD mode or vice versa.

<Small cell discovery>

Primary Synchronization Signal (PSS) / SSS as a downlink synchronization and reference signal for detecting any cell formed by any base station / eNB / RU / RRH in any terminal in the conventional 3GPP LTE / LTE-Advanced system (Secondary Synchronization Signal) and CRS (cell specific reference signal) were used. Accordingly, in a base station / eNB / RU / RRH constituting an arbitrary cell, a frequency division duplex (FDD) according to a frame structure type (for example, TDD / FDD) in units of 10 ms radio frames. In this case, PSS / SSS is transmitted through downlink subframes 0 and 5 and PSS / SSS is transmitted through downlink subframes 1 and 6 in time division duplex (TDD). Transmit CRS in subframe.

However, there is a need for a small cell on / off operation and the like in a small cell deployment scenario, and a discovery procedure related to the small cell on / off operation is required. Accordingly, a specific definition of a new small cell discovery procedure based on a new reference signal is needed in addition to the small cell discovery method based on the PSS / SSS and the CRS.

When a large number of small cells are introduced overlapping with any macro cell coverage, the cell splitting gain increases the overall system throughput, but the corresponding cell splitting There are disadvantages such as interference problem between small cell and macro cell, which reduces the effect of gain, and increased system power consumption and maintenance cost through introduction of multiple base stations. In particular, even when there is no UE connected within the small cell coverage, the small cell BS / eNB / RU / RRH needs to continuously transmit downlink signals including PSS / SSS and PBCH or CRS. Therefore, not only does not cause unnecessary power consumption in the small cell base station / eNB / RU / RRH, but also may cause unnecessary interference in data transmission and reception in the adjacent cell.

As a solution to this problem, the small cell on / off switching the small cell base station / eNB / RU / RRH into an inactive mode / state according to the number of terminals or the presence of the terminal connected to the small cell. / off) There is a need for operational support. However, if the dynamic or semi-static small cell on / off operation is supported, the cell measurement / discovery procedure of the UE in the small cell off state is performed. We need to define In addition to the existing PSS / SSS and CRS based cell measurement / discovery procedures, there is a need to define a CSI-RS or PRS based cell measurement / discovery method. In addition, there is a need for a definition of a new discovery RS based cell measurement / discovery procedure.

According to the present invention, in the small cell deployment scenario in which the aforementioned macro cell and the plurality of small cells are overlapped and introduced, the small cell according to the number of terminals, access terminals, or amount of data traffic is connected to any base station / eNB / RRH / RU. A method and apparatus for transmitting and receiving a downlink reference signal for small cell discovery for supporting on / off operations are provided. In particular, when an existing CSI-RS is used as a reference signal for small cell discovery, a specific method and apparatus for antenna port and radio resource allocation for a corresponding CSI-RS transmission will be described.

7 is a diagram illustrating an example of radio resource allocation of a downlink reference signal.

In the conventional 3GPP LTE / LTE-Advanced or less system as shown in FIG. 7, mobility such as handover and cell selection / reselection of a UE in a base station / eNB / RU / RRH forming an arbitrary cell All downlink subframes according to the number of antenna ports installed in a corresponding base station for downlink channel measurement of a terminal for secondary serving cell measurement for mobility management or carrier aggregation Had to transmit a cell-specific reference signal (CRS). However, in the downlink subframe configured as the MBSFN subframe, the corresponding CRS is transmitted only through the first OFDM symbol or the second OFDM symbol of the first slot.

That is, referring to FIG. 7, the base station transmitting the CRS maps the CRS using different radio resource elements according to the number of antenna ports.

Accordingly, the terminal accessing the base station receives the CRS transmitted through the corresponding downlink subframe for a predetermined time and measures RSRP / RSRQ. The terminal reports the measured RSRP / RSRQ result to the base station, and at the network side, whether the terminal performs a mobility management procedure such as a handover, and a secondary serving cell for carrier merging It determines whether the activation / deactivation for the (activation / deactivation). In addition, the CRS transmitted by the base station may be used for channel measurement for determining a handover target base station according to movement of a terminal connected to a neighboring base station and for channel selection for cell selection / reselection of idle state terminals. . Therefore, even if there is no terminal connected to the base station, the base station always transmits the above-mentioned CRS through all downlink subframes.

However, when a plurality of small cells are introduced while overlapping with a macro cell, there may be a case where no terminal is connected to the small cell. In this case, a downlink signal such as CRS and PSS / SSS or PBCH transmitted by the corresponding small cell may unnecessarily interfere with a macro cell or an adjacent small cell. In addition, there is a problem that unnecessary power consumption always occurs even in the corresponding small cell base station / eNB / RU / RRH to transmit CRS through every downlink subframe.

In order to solve this problem, a semi-static or dynamic small cell on / off operation scheme for changing a small cell to an inactive state when there is no terminal connected to any small cell or there is no data traffic. This can be considered. That is, the switching of the on / off mode may be considered to be a subframe level or a 10 ms radio frame level for any cell. Alternatively, a small cell on / off operation that supports an inactive mode operation that does not perform transmission of existing downlink PSS / SSS, CRS, or other downlink signals and channels through quasi-static on / off mode switching is considered.

When the small cell on / off operation described above is applied to any small cell base station as described above, when the small cell is in an inactive state, the CRS for downlink channel measurement is not transmitted in all downlink subframes. Therefore, an operation for performance of the discovery of the UE for the corresponding small cell is required. That is, since the above-described downlink signal is not transmitted when the small cell base station is in an inactive state, the terminal may provide information on whether the terminal is located in the coverage of the small cell base station in the inactive state or the channel state of the small cell in the inactive state. Can not confirm. Accordingly, the small cell base station in the inactive state needs to transmit a downlink reference signal for small cell discovery even in the inactive state. The terminal may measure the channel state of the small cell base station in an inactive state based on the received reference signal, and determine whether the mobile station is located in the coverage of the small cell base station.

In the present invention, a method of transmitting and receiving a downlink reference signal used for new small cell discovery will be described. In particular, the CSI-RS transmission and reception method for the small cell discovery when the CSI-RS is used for small cell discovery will be described. That is, when the small cell operates through different frequency bands from the macro cell as in the small cell deployment scenario described above, and the UE supports carrier aggregation between the macro cell frequency and the small cell frequency, the CSI-RS configuration for the small cell discovery is configured. Let's explain how.

8 is a diagram illustrating an example of an information element of measurement configuration information. 9 is a diagram illustrating an example of an information element of an RRCConnectionReconfiguration message with higher layer signaling according to the present invention.

8 and 9, according to measurement configuration information for an LTE / LTE-Advanced (E-UTRA) cell included in an RRCConnectionReconfiguration message as an example of higher layer signaling, measurement may be performed. Frequency information, measurement cell list configuration information, measurement gap configuration information, measurement reporting related configuration information, and the like are transmitted. In addition, in the RRCConnectionReconfiguration message related to the secondary cell addition, the corresponding SCellIndex information, cell identification information (PCID, DL-carrier frequency), and radio of the corresponding SCell are added to add an arbitrary SCell. Radio resource configuration related information and the like are transmitted. Specific information areas related to this are shown in FIGS. 8 and 9.

A description will be given of a method for setting an antenna port and a radio resource allocation of a downlink reference signal transmitted by a base station (small cell base station) in an inactive state according to the above description.

First, a method of determining a transmission antenna port of a reference signal will be described.

How to set CSI-RS transmit antenna port to be used as reference signal for discovery.

In a method for receiving a reference signal for small cell discovery, the terminal according to an embodiment of the present invention comprises the steps of: receiving a reference signal transmitted by a base station in an inactive state and transmitting antenna port information and radio resource allocation information of the reference signal; The reference signal can be checked using. Here, the reference signal may be the aforementioned CSI-RS.

 In other words, as described above, the CSI-RS may be used as a reference signal for discovery / measurement of an inactive cell. As such, CSI-RS is defined to use as a new cell discovery / measurement reference signal, or a cell discovery / configuration of a corresponding SCell is performed through an RRC connection reconfiguration message for measurement configuration information or secondary cell addition. If the CSI-RS is defined as a measurement reference signal, it is necessary to define a CSI-RS port and a CSI-RS transmission resource for CSI-RS transmission in a corresponding SCell.

For example, according to the CSI-RS configuration method, when configuring CSI-RS for an arbitrary terminal, the number of antenna ports, CSI-RS radio resource configuration information, CSI-RS subframe configuration information, and the like are transmitted through RRC signaling. Based on this, the corresponding CSI-RS port 15, CSI-RS port {15,16}, and CSI-RS port {15,16, respectively according to the number of CSI-RS antenna ports (1, 2, 4 or 8) in the corresponding cell, respectively. 17,18} through the CSI-RS port {15,16,17,18,19,20,21,22}.

FIG. 10 is a diagram illustrating an example of an information element of higher layer signaling including configuration information for CSI-RS transmission. FIG. 11 is a diagram illustrating another example of an information element of higher layer signaling including configuration information for CSI-RS transmission. Referring to FIG. 10, an information element of an RRC message defined for CSI-RS configuration of 3GPP Rel-10 may be configured as shown in FIG. 10. In addition, referring to FIG. 11, an information element of an RRC message defined for CSI-RS configuration of 3GPP Rel-11 may be configured as shown in FIG. 11. In addition, FIG. 11 may be defined to additionally set the scramblingIdentity value and QCL related information for generating a CSI-RS sequence. Meanwhile, the method defined in the document of 3GPP TS 36.211 may be used as a transmission method of the CSI-RS using FIGS. 10 and 11.

Hereinafter, when the CSI-RS of the present invention is set as a reference signal for discovery / measurement for a certain SCell, an antenna port setting method for corresponding CSI-RS transmission will be described. That is, unlike a conventional CSI-RS, a reference signal for discovery or cell measurement transmitted by an inactive base station needs to newly set information on a transmission antenna port. Therefore, a method of setting a transmission antenna port according to each embodiment will be described.

Embodiment 1: Fixing Transmission Antenna Ports for Discovery Reference Signals.

According to an embodiment of the present invention, when a CSI-RS is transmitted as a reference signal for small cell discovery, it may be defined to use a fixed antenna port number. Specifically, the transmission antenna port information checked by the terminal includes information on a fixed antenna port identification number predefined for CSI-RS transmission as a discovery reference signal, and the fixed antenna port identification number is a CSI-RS transmission antenna port. It can be defined as any one of the antenna port identification number of the eight antenna ports from 15 to 22 defined as or 2, 4 or 8 can be defined. That is, if the CSI-RS is set as the reference signal for the cell discovery / measurement described above in any cell, the transmit antenna port of the CSI-RS for the cell discovery / measurement may be defined to use a fixed CSI-RS antenna port. Can be.

For example, when CSI-RS is used as a reference signal for small cell discovery, one CSI-RS transmit antenna port may be fixed as a CSI-RS transmit antenna port for corresponding cell discovery / measurement. Specifically, when a CSI-RS is used as a discovery reference signal for an arbitrary cell, the CSI-RS may be fixed to be transmitted through the antenna port 15 at all times. Alternatively, the antenna port 16 may be fixed to the corresponding CSI-RS transmission antenna port, or one of the antenna ports 17, 18, 19, 20, 21, and 22 may be defined as the CSI-RS transmission antenna port for discovery.

As another example, when a CSI-RS is used as a discovery reference signal, it may be defined to transmit through a combination of two antenna ports fixed as a corresponding CSI-RS transmission antenna port for discovery. In this case, the fixed two antenna port combinations have different resource elements such as {15,17}, {16.18}, {15,19}, {17,21}, {19,21}, and {20,22}. Can be fixed with any two antenna port combinations.

As another example, when the CSI-RS is used as the discovery reference signal, the CSI-RS may be defined to transmit through a combination of four antenna ports fixed as the discovery CSI-RS transmission antenna port. Even in this case, the fixed four antenna port combinations can be fixed by any four antenna port combinations using different resource elements such as {15,17,19,21} and {16,18,20,22}. have.

As another example, when the CSI-RS is used as the discovery reference signal, the CSI-RS transmission antenna port for discovery may be fixed to transmit using all eight antenna ports from 15 to 22.

Second embodiment: Transmission antenna port information transmission for discovery reference signal.

In another embodiment of the present invention, the terminal may receive information on a transmission antenna port configured for the reference signal. Information on the transmit antenna port may be received through higher layer signaling. Meanwhile, the transmission antenna port information received through higher layer signaling may be configured as bitmap information or may be configured as index information indicating an index value of the transmission antenna port table.

Specifically, for example, a base station transmitting CSI-RS for cell discovery / measurement may directly set a corresponding CSI-RS transmit antenna port for cell discovery / measurement among the above eight CSI-RS antenna ports in a corresponding cell. This may be set to be transmitted to the terminal through higher layer signaling (eg, an RRC message). In this case, the transmission antenna port information may be included in the measurement configuration described above or the RRCConnectionReconfiguration message for adding the SCell. For example, corresponding CSI-RS transmission antenna port information for cell discovery / measurement may be set in a bitmap method. That is, to configure the bitmap consisting of 8 bits (bits) for the eight antenna port transmission settings from each antenna port 15 to 22 to transmit the corresponding discovery / measurement CSI-RS transmission antenna port information to the terminal can do. As another example, the transmission antenna port information is a table mapping method for each discovery / measurement CSI-RS transmission antenna port configuration candidate (candidate) is composed of a table, the discovery / measurement CSI-RS for use in the cell Index information indicating the transmit antenna port may be signaled.

12 illustrates a CSI-RS transmit antenna port table according to an embodiment of the present invention. The above-described transmission antenna port table may be stored in advance as shown in FIG. However, since FIG. 12 is described by way of example in order to facilitate understanding, the present invention is not limited to the specific values of the antenna port and the table configured at each index.

Third embodiment: The number of transmit antenna ports for the discovery reference signal is fixed, and index information according to the number of ports is transmitted.

FIG. 13 is a diagram illustrating a CSI-RS transmit antenna port table according to the number of transmit antenna ports according to another embodiment of the present invention.

In a method of confirming a reference signal by a terminal according to another embodiment of the present invention, the transmission antenna port information for identifying the reference signal indicates an index value of the transmission antenna port table set according to the number of the transmission antenna ports stored in advance. It may be received including the index information.

Referring to FIG. 13, the number of CSI-RS transmit antenna ports is fixed and based on this, the CSI-RS transmit antenna ports may be set to receive corresponding information. For example, as shown in FIG. 13, the number of transmit antenna ports for RS transmission may be set to one, two, four, or eight. Since all antenna ports are used when 8 fixed, the transmit antenna port table may not be necessary, and different transmit antenna port tables may be stored in advance according to the number of transmit antenna ports as shown in FIG. 13. That is, the number of CSI-RS transmit antenna ports for cell discovery / measurement may be fixed to 1, or may be fixed to 2 or 4, and based on this, each index information of the discovery CSI-RS transmit antenna port table may be used for higher layer signaling. Can be received through. Accordingly, the terminal may store any one of the transmission antenna port tables according to the fixed number of transmission antenna ports in the table of FIG. 13, and transmit the antenna for the reference signal using index information included in the received transmission antenna port information. You can check the information on the port.

As described above, the transmission antenna port for the reference signal may be set in various ways, and the terminal may identify the reference signal using the corresponding transmission antenna port information.

Hereinafter, each embodiment of a method of setting radio resource element information allocated to a reference signal will be described.

A method of setting CSI-RS radio resource allocation to be used as a reference signal for discovery.

A method of setting a resource for transmitting the CSI-RS for cell discovery / measurement will be described.

The terminal of the present invention may use radio resource allocation information to which the reference signal is allocated to identify the received reference signal. That is, the CSI-RS signal transmitted by the base station in the inactive state can be confirmed using the information on the radio resource allocation of the CSI-RS for the reference signal. Hereinafter, each embodiment of a method for obtaining radio resource allocation information will be described.

First Embodiment: Confirming Radio Resource Allocation Information Using Cell Physical Cell Identification Information and Frame Structure Type.

14 is a diagram illustrating an example of a radio resource configuration table for CSI-RS transmission for each frame structure type in the case of a normal cyclic prefix.

15 is a diagram illustrating an example of a radio resource configuration table for CSI-RS transmission for each frame structure type in the case of an extended cyclic prefix.

In order to configure a general CSI-RS radio resource, each CSI-RS transmit antenna port according to a cyclic prefix (CP) length and a frame structure according to the CSI-RS transmission antenna port as shown in the table of FIGS. A resource configuration table for the -RS may be configured. 14 is an example of a resource configuration table configured in the case of a normal cyclic prefix, and FIG. 15 is an example of a resource configuration table configured in the case of an extended cyclic prefix.

In contrast, the embodiment of the present invention describes a method of implicitly setting the CSI-RS transmission radio resource allocation information for cell discovery / measurement. For example, the radio resource allocation information may be configured to allocate the corresponding CSI-RS transmission radio resource as a function of physical cell identification information (PCID) of a cell transmitting the discovery / measurement CSI-RS. For example, in the case of a normal CP in a cell of frame structure type 1, a value of the corresponding PCID mod 20 may be defined as a corresponding CSI-RS transmission radio resource setting value. In addition, in the case of a cell of frame structure type 1 (frame structure type 1), in the case of an extended CP, a value of PCID mod 16 may be defined as a corresponding discovery / measurement CSI-RS transmission radio resource setting value. Similarly, in case of a frame of type 2 (frame structure type 2) cell, in case of normal CP, a value of the corresponding PCID mod 32 may be defined as a corresponding discovery / measurement CSI-RS transmission radio resource setting value. In addition, in the case of a cell of frame structure type 2 (frame structure type 2), in the case of an extended CP, a value of PCID mod 28 may be defined as a corresponding discovery / measurement CSI-RS transmission radio resource setting value.

Second Embodiment: Confirming Radio Resource Allocation Information Using Cell Physical Cell Identification Information.

As another example, regardless of the frame structure type, in the case of normal CP, the value of PCID mod 20 is extended to the value of PCID mod 16 in the case of extended CP. It may be defined as a CSI-RS transmission radio resource configuration value. That is, unlike the first embodiment, in the second embodiment, radio resource allocation information can be checked only by using the type of cyclic prefix and the physical cell identification information without considering the frame structure type.

In the case of the first embodiment and the second embodiment, the terminal may receive physical cell identification information (PCID) of the corresponding cell through higher layer signaling. For example, higher layer signaling including physical cell identification information may be the above-described measurement configuration or RRCConnectionReconfiguration message for SCell addition.

Third Embodiment: Check radio resource allocation information through higher layer signaling.

The terminal of the present invention may directly receive radio resource allocation information of the aforementioned reference signal through higher layer signaling. For example, the UE may directly include the allocation information of the corresponding CSI-RS radio resource in the above-described measurement configuration for adding the SCell or the RRC connection reconfiguration message for adding the SCell.

The terminal may directly obtain radio resource allocation information of the reference signal by using the received higher layer signaling.

In the above, a method of setting a transmission antenna port and a radio resource allocation method of a reference signal transmitted by a base station configured in an inactive state has been described with reference to each embodiment. Hereinafter, the above-described present invention will be described once again focusing on the operation of the terminal and the base station.

16 is a view for explaining the operation of the terminal according to another embodiment of the present invention.

In a method for receiving a reference signal for small cell discovery, the terminal according to another embodiment of the present invention, receiving a reference signal transmitted by a base station in an inactive state and transmitting antenna port information and radio resource allocation of the reference signal Identifying the reference signal using the information.

Referring to FIG. 16, in a method of receiving a reference signal for small cell discovery, the terminal includes receiving a reference signal transmitted by a base station in an inactive state (S1610). That is, the terminal may receive a reference signal for cell discovery / measurement transmitted by a base station (small cell base station) in an inactive state. For example, the reference signal may be a channel state indicator reference signal (CSI-RS).

On the other hand, the terminal includes the step of identifying the reference signal using the transmission antenna port information and radio resource allocation information of the reference signal (S1620). The terminal may use transmission antenna port information and radio resource allocation information through which the reference signal is transmitted to identify the received reference signal.

For example, the transmission antenna information includes information about a fixed antenna port identification number preset for reference signal transmission, and the fixed antenna port identification number may be set to one, two, four, or eight. That is, the terminal can obtain the transmission antenna information by using a fixed antenna port identification number for transmitting the reference signal known in advance.

As another example, higher layer signaling including transmission antenna port information may be received. The transmission antenna port information may include bitmap information indicating a transmission antenna port or index information indicating an index value of a preset transmission antenna port table. For example, the terminal may check the information on the transmission antenna port through the transmission antenna information included in the bitmap scheme in the received higher layer signaling. Alternatively, the terminal may store a preset transmission antenna port table and may check information on the transmission antenna port by using the index information included in the higher layer signaling described above.

As another example, the terminal prestores a transmission antenna port table set according to the number of transmission antenna ports, and receives transmission antenna information including index information indicating a specific index value of the transmission antenna port table through higher layer signaling. By doing so, information about the transmission antenna can be confirmed.

The higher layer signaling described above may include a measurement configuration or an RRC connection reconfiguration message. In addition, the terminal may perform all the operations according to the above-described method of setting the transmission antenna port.

The terminal may check the reference signal using radio resource allocation information of the reference signal.

For example, the terminal may check information on radio resource allocation of the reference signal using physical cell identification information (PCID) of the base station of radio resource allocation information included in higher layer signaling. In more detail, the terminal may identify the reference signal based on at least one of physical cell identification information, a cyclic prefix (CP) type, and a frame structure type. Alternatively, the reference signal may be checked based on the type of the physical cell identification information and the cyclic prefix regardless of the frame structure type.

As another example, the terminal may explicitly identify the radio resource allocation information by using radio resource allocation information directly included in higher layer signaling. That is, the terminal may receive higher layer signaling to check allocation information on radio resources of the reference signal.

The higher layer signaling described above may include a measurement configuration or an RRC connection reconfiguration message. In addition, the terminal may perform all operations according to the above-described radio resource setting method.

The above-described higher layer signaling including transmission antenna port information or radio resource allocation information may be transmitted from a base station having an RRC connection with the terminal. That is, since the terminal does not have an RRC connection with the base station in the deactivated state, the base station having an RRC connection with the terminal, such as a macro cell base station, transmits transmission antenna port information and radio resource allocation information related to the transmission of the reference signal of the base station in the deactivated state. Can transmit

17 is a diagram for explaining the operation of a base station according to another embodiment of the present invention.

In a method for transmitting a reference signal for small cell discovery, the base station according to another embodiment of the present invention generates a reference signal by configuring the base station in an inactive state and setting transmission antenna port information and radio resource allocation information. And transmitting a reference signal using the transmission antenna port information and the radio resource allocation information.

Referring to FIG. 17, the base station includes configuring the base station in an inactive state (S1710). The deactivation state may be determined according to the number of terminals located in the cell provided by the corresponding base station or the amount of data traffic, and the like. In the case of the small cell base station, the deactivation state is activated or deactivated in order to reduce power consumption and signal interference. You can change it. The state change may be made at the subframe level or the radioframe level. Therefore, when the change to the inactive state is triggered, the base station can configure the state of the base station to the inactive state.

The base station sets a transmission antenna port information and radio resource allocation information to generate a reference signal (S1720). As described above, the reference signal is transmitted by the base station in an inactive state. The terminal may receive the reference signal and perform cell measurement or cell detection. Accordingly, the base station can generate the reference signal by setting the transmission antenna port information for transmitting the reference signal and the radio resource allocation information for allocating the reference signal. The transmission antenna port information includes information on a fixed antenna port identification number preset for reference signal transmission, and the fixed antenna port identification numbers may be set to one, two, four, or eight. Alternatively, the radio resource allocation information may be determined by physical cell identification information (PCID) of the base station. Alternatively, the radio resource allocation information may be determined based on one or more information of physical cell identification information, cyclic prefix (CP) type, and frame structure type.

Here, generating the reference signal means setting a transmission antenna port for transmitting the reference signal and setting a radio resource.

The base station transmits the reference signal using the transmission antenna port information and the radio resource allocation information (S1730). For example, the base station transmits a reference signal using the set transmission antenna port and the radio resource using the set transmission antenna port information and the corresponding radio resource allocation information.

The aforementioned reference signal may be a channel state indicator reference signal (CSI-RS).

The present invention described above provides an effect of reducing signal interference by changing a base station providing a small cell to an inactive state in an environment in which macro cells and small cells overlap. In addition, the present invention has the effect of providing a specific procedure and method for the terminal to receive and confirm the reference signal transmitted by the base station in an inactive state. In addition, the present invention, the terminal receives the reference signal to measure the channel state of the base station in the inactive state, and based on this connection to the base station in the inactive state by reducing the power consumption and signal interference of the communication system and a large amount of data Provides a processable effect.

The configuration of a terminal and a base station capable of performing all the operations of the present invention described above will be briefly described.

18 is a view showing the configuration of a user terminal according to another embodiment of the present invention.

Referring to FIG. 18, a user terminal 1800 according to another embodiment of the present invention includes a receiver 1830, a controller 1810, and a transmitter 1820.

The terminal 1800 receiving a reference signal for small cell discovery of the present invention uses a receiver 1830 for receiving a reference signal transmitted by a base station in an inactive state, and transmit antenna port information and radio resource allocation information of the reference signal. And a controller 1810 for checking a reference signal. For example, the reference signal may be a channel state indicator reference signal (CSI-RS).

The receiver 1830 may further receive higher layer signaling including transmission antenna port information or radio resource allocation information. Higher layer signaling may include a measurement configuration or an RRC connection reconfiguration message. In addition, the receiver 1830 receives downlink control information, data, and a message from a base station through a corresponding channel.

The transmitter 1820 transmits uplink control information, data, and a message to a base station through a corresponding channel.

The controller 1810 checks the reference signal using the transmission antenna port information and the radio resource allocation information of the reference signal. For example, the transmission antenna information includes information about a fixed antenna port identification number preset for reference signal transmission, and the fixed antenna port identification number may be set to one, two, four, or eight. That is, the control unit 1810 can obtain the transmission antenna information by using a fixed antenna port identification number for transmitting the reference signal known in advance. As another example, the controller 1810 may check the reference signal using bitmap information indicating a transmission antenna port of the received transmission antenna information or index information indicating an index value of a preset transmission antenna port table. As another example, the controller 1810 may check the information on the transmit antenna using index information indicating a specific index value of the transmit antenna port table and the received transmit antenna port table set according to the number of transmit antenna ports stored in advance. have.

In addition, the controller 1810 may identify the reference signal using radio resource allocation information of the reference signal. For example, the controller 1810 may check information on radio resource allocation of the reference signal using physical cell identification information (PCID) of the base station of radio resource allocation information included in higher layer signaling. In more detail, the terminal may identify the reference signal based on at least one of physical cell identification information, a cyclic prefix (CP) type, and a frame structure type. Alternatively, the reference signal may be checked based on the type of the physical cell identification information and the cyclic prefix regardless of the frame structure type. As another example, the controller 1810 may explicitly identify the radio resource allocation information by using radio resource allocation information directly included in higher layer signaling. That is, the terminal 1800 may receive higher layer signaling to confirm allocation information on radio resources of the reference signal.

In addition, the controller 1810 may control the operation of the terminal according to the terminal of the present invention to identify the reference signal using the transmission antenna port information and radio resource allocation information.

19 is a diagram illustrating a configuration of a base station according to another embodiment of the present invention.

Referring to FIG. 19, a base station 1900 according to another embodiment of the present invention includes a receiver 1930, a controller 1910, and a transmitter 1920.

The controller 1910 may configure the base station in an inactive state. The deactivation state may be determined according to the number of terminals located in the cell provided by the corresponding base station or the amount of data traffic, and the like. In the case of the small cell base station, the deactivation state is activated or deactivated in order to reduce power consumption and signal interference. You can change it. The state change may be made at the subframe level or the radioframe level. Therefore, the controller 1910 may configure the state of the base station 1900 as an inactive state when a change to the inactive state is triggered.

Also, the controller 1910 may generate a reference signal by setting transmission antenna port information and radio resource allocation information. The controller 1910 may generate a reference signal by setting transmission antenna port information for transmitting the reference signal and radio resource allocation information for allocating the reference signal. The transmission antenna port information includes information on a fixed antenna port identification number preset for reference signal transmission, and the fixed antenna port identification numbers may be set to one, two, four, or eight. Alternatively, the radio resource allocation information may be determined by physical cell identification information (PCID) of the base station. Alternatively, the radio resource allocation information may be determined based on one or more information of physical cell identification information, cyclic prefix (CP) type, and frame structure type.

In addition, the controller 1910 may control the overall operation of the base station according to the base station of the present invention to set the transmission antenna port information and radio resource allocation information to generate and transmit a reference signal.

The transmitter 1920 transmits a reference signal using the transmission antenna port information and the radio resource allocation information. In addition, the transmitter 1920 transmits a reference signal using the set transmission antenna port and the radio resource by using the set transmission antenna port information and the corresponding radio resource allocation information. The reference signal may be a channel state indicator reference signal (CSI-RS). In addition, the transmitter 1920 may transmit a downlink signal, data, and a message to the terminal.

The receiver 1930 may receive higher layer signals, data, and messages from the terminal.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and changes without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

CROSS-REFERENCE TO RELATED APPLICATION

This patent application is related to the patent application No. 10-2014-0003079 filed in Korea on January 09, 2014 and the patent application No. 10-2015-0000031 filed in Korea on January 02, 2015. Priority is claimed under section (a) (35 USC § 119 (a)), all of which is incorporated by reference in this patent application. In addition, if this patent application claims priority for the same reason for countries other than the United States, all its contents are incorporated into this patent application by reference.

Claims (20)

1. A method for receiving a reference signal for small cell discovery by a terminal,

   Receiving a reference signal transmitted by a base station in an inactive state; And

   And identifying the reference signal by using transmission antenna port information and radio resource allocation information of the reference signal.
2. The method of claim 1,

   The reference signal is,

   And a channel state indicator reference signal (CSI-RS).
3. The method of claim 1,

   The transmission antenna port information is

   Includes information on a fixed antenna port identification number preset for the reference signal transmission,

   Wherein the fixed antenna port identification number is set to any one, two, four or eight of eight antenna port identification numbers from 15 to 22.
4. The method of claim 1,

   Before the step of receiving the reference signal,

   Receiving higher layer signaling including the transmit antenna port information or the radio resource allocation information.
5. The method of claim 4, wherein

   The transmission antenna port information is

   And bitmap information indicating a transmission antenna port or index information indicating an index value of a preset transmission antenna port table.
6. The method of claim 4, wherein

   The transmission antenna port information is

   And index information indicating an index value of a transmission antenna port table set according to the number of transmission antenna ports stored in advance.
7. The method of claim 4, wherein

   The radio resource allocation information,

   It includes physical cell identification information (Physical Cell IDentity, PCID) of the base station,

   Confirming the reference signal,

   And identifying the reference signal based on at least one of the physical cell identification information, the cyclic prefix (CP) type, and the frame structure type.
8. In the method for the base station to transmit a reference signal for small cell discovery,

   Configuring the base station in an inactive state;

   Generating the reference signal by setting transmission antenna port information and radio resource allocation information; And

   And transmitting the reference signal using the transmission antenna port information and the radio resource allocation information.
9. The method of claim 8,

   The reference signal is,

   And a channel state indicator reference signal (CSI-RS).
10. The method of claim 8,

    The transmission antenna port information is

    Includes information on a fixed antenna port identification number preset for the reference signal transmission,

    Wherein the fixed antenna port identification number is set to any one, two, four or eight of eight antenna port identification numbers from 15 to 22.
11. The method of claim 8,

    The radio resource allocation information,

    And determined by physical cell identification information (PCID) of the base station.
12. The method of claim 11,

    The radio resource allocation information,

    And determined based on at least one of the physical cell identification information, the cyclic prefix (CP) type, and the frame structure type.
13. A terminal for receiving a reference signal for small cell discovery, the terminal comprising:

    Receiving unit for receiving a reference signal transmitted by the base station in the inactive state; And

    And a control unit for identifying the reference signal by using the transmission antenna port information and the radio resource allocation information of the reference signal.
14. The method of claim 13,

    The reference signal is,

    Terminal comprising a Channel State Indicator Reference Signal (CSI-RS).
15. The method of claim 13,

    The transmission antenna port information is

    Includes information on a fixed antenna port identification number preset for the reference signal transmission,

    Wherein the fixed antenna port identification number is set to any one, two, four or eight of eight antenna port identification numbers from 15 to 22.
16. The method of claim 13,

    The receiving unit,

    And receiving higher layer signaling including the transmission antenna port information or the radio resource allocation information.
17. The method of claim 16,

    The transmission antenna port information is

    And bitmap information indicating a transmission antenna port or index information indicating an index value of a preset transmission antenna port table.
18. The method of claim 16,

    The transmission antenna port information is

    And index information indicating an index value of a transmission antenna port table set according to the number of transmission antenna ports stored in advance.
19. The method of claim 16,

    The radio resource allocation information,

    It includes physical cell identification information (Physical Cell IDentity, PCID) of the base station,

    The control unit,

    And identifying the reference signal based on at least one of the physical cell identification information, the cyclic prefix (CP) type, and the frame structure type.
20. A base station transmitting a reference signal for small cell discovery,

    Configure the base station to be inactive,

    A control unit for generating the reference signal by setting transmission antenna port information and radio resource allocation information; And

    And a transmitter for transmitting the reference signal using the transmission antenna port information and the radio resource allocation information.

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