KR20140058976A - Method and apparatus for transmitting/receiving reference signal and channel information in wireless communication system - Google Patents

Abstract

The present invention relates to a method for transmitting and receiving reference signals and channel information in a wireless communication system.
The method includes receiving a plurality of reference signals mapped to different radio resources from a base station, measuring a received power intensity with respect to each of the plurality of reference signals, And transmitting the channel information including the information indicating the reference signal to the base station.

Description

TECHNICAL FIELD [0001] The present invention relates to a method and apparatus for transmitting and receiving reference signals and channel information in a wireless communication system,

The present invention relates to a wireless communication system, and more particularly, to a method of transmitting and receiving a reference signal and channel information.

As communications systems evolved, consumers, such as businesses and individuals, used a wide variety of wireless terminals.

Currently, wireless communication systems such as 3GPP, LTE (Long Term Evolution) and LTE-A (LTE Advanced) are high-speed and large-capacity communication systems capable of transmitting and receiving various data such as video and wireless data, There is a need to develop a technology capable of transmitting large-capacity data that is similar to a wired communication network, and it has been necessary to improve the system performance by minimizing the reduction of information loss and increasing the system transmission efficiency.

In order to solve the demand for high speed information transmission, the latest communication system uses a transmission and reception technique using multiple input multiple output (MIMO) in both the transmission and reception ends. The MIMO communication system has a structure in which each terminal receives or transmits a signal to one or a plurality of base stations connected thereto, and each terminal reports information on a forward channel to the base station to help transmit information of the base station.

In this context, in one aspect, an object of the present invention is to provide a method by which a multi-dimensional antenna array can be used in a MIMO system.

In another aspect, an object of the present invention is to provide a method for reducing overhead for measuring and reporting channel information.

According to one aspect of the present invention, there is provided a method of transmitting a reference signal and a channel information by a base station in a wireless communication system, the method comprising: receiving a plurality of reference signals precoded in different matrices, Mapping to a radio resource and transmitting to the terminal; And channel information including information indicating a reference signal having a highest received power level at the terminal or at least one reference signal determined according to a descending order or an ascending order of a received power intensity at the terminal, And receiving the channel information from the terminal, the channel information including information on the channel information.

According to another aspect of the present invention, there is provided a method of receiving a reference signal and transmitting channel information in a wireless communication system, the method comprising: receiving a plurality of reference signals From a base station; Measuring a received power intensity for each of the plurality of reference signals; And channel information including information indicating a reference signal having the largest received power intensity among the plurality of reference signals or information indicating one or more reference signals determined in descending order or ascending order of the received power intensity, And transmitting the reference signal to the base station.

According to another aspect of the present invention, there is provided a base station for transmitting a reference signal and receiving channel information in a wireless communication system, the base station comprising: a controller for precoding each of a plurality of reference signals using different matrices; A transmitter for mapping the plurality of precoded reference signals to different radio resources and transmitting the same to a mobile station; And one or more reference signals determined based on channel information including information indicating a highest reference signal strength of a received signal strength at the user equipment, or at least one reference signal determined according to a descending order or an ascending order of a received power intensity at the user equipment And a receiver for receiving channel information including information from the terminal.

According to another aspect of the present invention, there is provided an apparatus for receiving a reference signal and transmitting channel information in a wireless communication system, comprising: a plurality of reference signals mapped to different radio resources in a physical resource block pair; A receiving unit for receiving from a base station; A control unit for measuring a received power intensity with respect to each of the plurality of reference signals; And channel information including information indicating a reference signal having the largest received power intensity among the plurality of reference signals or information indicating one or more reference signals determined in descending order or ascending order of the received power intensity, And a transmitter for transmitting information to the base station.

According to the present invention, a multi-dimensional antenna array can be applied in a MIMO system, and overhead for measuring and reporting channel information can be reduced.

FIG. 1 is a schematic view of a wireless communication system to which embodiments are applied.
2 is a diagram showing a region where a strong electric field of the antenna is formed and a shaded region.
3 is a view for explaining vertical beam forming using a multiple antenna array and a multiple antenna array.
4 is a diagram illustrating a base station transmitting a reference signal and receiving channel state information and channel quality information from a terminal.
5 is an exemplary illustration of a CSI-RS antenna mapping for a base station to transmit a reference signal in a two-dimensional antenna array.
6 and 7 are flowcharts illustrating an exemplary procedure for a UE to receive CSI-RS and to feedback channel information through channel measurement.
8 is a diagram showing an example of mapping and mapping of a CSI-RS to a resource block pair.
9 is a schematic diagram of a process of estimating and reporting channel state information using CSI-RS or CRS.
10 is a diagram illustrating that precoded CSI-RS is transmitted and received and channel information including an RS index is fed back in a wireless communication system according to an embodiment of the present invention.
11 is a flowchart illustrating a process in which precoded CSI-RS is transmitted and received and channel information including information indicating a maximum received power RS is transmitted and received in a wireless communication system according to an embodiment of the present invention.
12 is a diagram illustrating an example of an information structure for transmitting and receiving RSs for channel estimation according to 2D / 3D MIMO and for feeding back channel information.
13 is a diagram for explaining that a precoded CSI-RS is mapped to different radio resources.
FIG. 14 is a flowchart illustrating a process of feeding back information indicating a reference signal having a large received power, according to an embodiment of the present invention.
15 is a diagram illustrating an example in which a channel estimation RS is mapped to an antenna array in 3D MIMO.
16 is a diagram showing that a reference signal is precoded and mapped to an antenna port.
FIG. 17 is a diagram illustrating another example of an information structure for transmitting and receiving channel estimation RSs according to 2D / 3D MIMO and for feeding back channel information.
18 is a block diagram of a base station according to an embodiment of the present invention.
19 is a block diagram of a terminal according to an embodiment of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. 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 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 invention rather unclear.

In describing the components of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are intended to distinguish the constituent elements from other constituent elements, and the terms do not limit the nature, order or order of the constituent elements. When a component is described as being "connected", "coupled", or "connected" to another component, the component may be directly connected to or connected to the other component, It should be understood that an element may be "connected,""coupled," or "connected."

FIG. 1 is a schematic view of a wireless communication system to which embodiments are applied.

The wireless communication system 100 is widely deployed to provide various communication services such as voice, packet data, and so on.

1, a wireless communication system 100 includes a user equipment (UE) 110 and a base station 120 (BS).

The terminal 110 in the present specification is a comprehensive concept of a user terminal in a wireless communication. The terminal 110 may be a user terminal in a Wideband Code Division Multiple Access (WCDMA), Long Term Evolution (LTE), High Speed Packet Access (HSPA) Equipment, as well as mobile station (MS), user terminal (UT), subscriber station (SS) and wireless device in GSM (Global System for Mobile communications) .

The terminal 110 can perform feedback of channel information to be described below, and provides the apparatus.

A base station 120 or a cell is generally a fixed station that communicates with a terminal 110 and includes a Node-B, an evolved Node-B (eNB), a Base Transceiver (BTS) System, an access point, a relay node, and the like.

The base station 120 transmits a reference signal to the terminal 110, receives channel information from the terminal 110, and can transmit data or signals using the channel information.

That is, the base station 120 or the cell in the present specification should be construed as a comprehensive meaning indicating a partial area covered by a BSC (Base Station Controller) in CDMA (Code Division Multiple Access), a Node-B in WCDMA And covers various coverage areas such as megacell, macrocell, microcell, picocell, femtocell, and relay node communication range.

Herein, the terminal 110 and the base station 120 are used in a broad sense as the two transmitting and receiving subjects used to implement the technical or technical idea described in this specification, and are not limited by a specific term or word .

There is no limit to the multiple access scheme that is applied to the wireless communication system 100. Various multiple access schemes 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- Can be used.

A TDD (Time Division Duplex) scheme in which uplink and downlink transmissions are transmitted using different time periods, or an FDD (Frequency Division Duplex) scheme in which they are transmitted using different frequencies can be used.

One embodiment is applied to asynchronous wireless communication that evolves into LTE (Long Term Evolution) and LTE-advanced via GSM, WCDMA, and HSPA, and synchronous wireless communication that evolves into CDMA, CDMA-2000, and UMB (Ultra Mobile Broadband) . The present invention should not be construed to be limited or limited to a specific wireless communication field and should be construed as including all technical fields to which the idea of the present invention can be applied.

The wireless communication system 100 to which embodiments are applied may support uplink and / or downlink HARQ (Hybrid ARQ) and may use a channel quality indicator (CQI) for link adaptation. For example, the downlink may be OFDMA (Orthogonal Frequency Division Multiple Access), the uplink may be a Single Carrier-Frequency Division Multiple Access (SC-FDMA) ) Can be used.

The wireless communication system 100 includes a single user multiple input multiple output (SU-MIMO) scheme for transmitting information to a user through a specific band using multiple antennas and a high speed information transmission (MU-MIMO) scheme, which transmits information over the same band to multiple users at the same time using multiple antennas, can be considered. MU-MIMO allows two users to share a band when two or more user terminals have a high channel propagation gain for the same band, so that a larger number of users can use the broadband gain, It is possible to use this good band to improve the overall spectral efficiency.

The wireless communication system 100 may use a 3D Dimensional Multiple Input Multiple Output (MIMO) technique using a multi-dimensional antenna array. Here, a 2D MIMO scheme is used for signal manipulation on a two-dimensional plane using a one-dimensional antenna array, and a MIMO system is implemented on a space including a vertical direction using a multidimensional antenna array. .

FIG. 2 is a view showing a region where the strong electric field of the antenna is formed and a shaded region, and FIG. 3 is a view for explaining vertical beam forming using a multiple antenna array and a multiple antenna array. 2 and 3, a method of using the 3D MIMO technique by the wireless communication system 100 will be described as an example of solving the problem that the shadow region appears according to the propagation characteristics of the antenna and an example for solving such a problem.

2 (a) shows the effective angle of strong electric field in the vertical direction of the antenna in such a wireless communication system. As can be seen from FIG. 2 (a), since the range of the effective angle of strong electric field in the vertical direction of the antenna is formed forward, a shaded area (shaded area) may appear below and above the area where the antenna is installed . In order to solve the problem of the shaded area due to the range of the effective angle of the strong electric field in the vertical direction of the antenna, the antenna may be tilted as shown in FIG. 2 (b). Fig. 2 (b) shows that the antenna is tilted so that the range of effective angles of the strong electric field system of the antenna is directed downward (downward).

The antenna may be installed at a relatively high position (equivalent to 25 m from the ground) to have a broader radio wave radius, and this antenna is arranged so as to be tilted toward the ground in order to solve the problem of the shadow area appearing downward as described above )can do. This antenna installation method is called physical antenna tilting.

However, due to the downward tilting of the antenna, the problem of the generation of the shaded area in the lower part can be partially solved, but the problem of the occurrence of the shaded area in the upper part (high layer) can not be solved or can be deteriorated. FIG. 2C is a diagram showing a strong electric field region and a shadow region according to antenna tilting. As can be seen from FIG. 2C, the shaded area in the service area of the ground terminal 110 is narrowly formed, but the shaded area in the service area of the high-level terminal 110 corresponding to the upper part is wide . These problems can cause serious problems of reducing communication capacity in urban areas where high-rise buildings are common.

Another method for solving the above problem is to adopt a space division transmission method according to the altitude through the soft tilting and multidimensional precoding using the multi-dimensional antenna array of the wireless communication system 100.

3 (a) and 3 (b) show an 8 × 4 antenna array and an 8 × 8 antenna array, respectively, as an example of a multi-dimensional antenna array.

FIG. 3 (c) is a diagram depicting implementing adaptive tilting or spatial division multiplexing (SDM) using such a multidimensional antenna array. 3C, when the base station 120 transmits a signal to the terminal 110 located at a position higher than the antenna of the base station 120, the base station 120 transmits the phase difference to the antennas arranged in the vertical domain And performs signal processing so that the subject signal supports strong radio waves in the upward direction. Such an operation can be defined in terms of soft tilting in correspondence with physical antenna tilting. On the other hand, when a signal is to be transmitted to the terminal 110 located at a position lower than the antenna of the base station 120, a phase difference is given in the opposite manner to the above case, Processing can be performed. In addition, if a sufficient number of transmission antennas are arranged in the vertical direction to support a high resolution, spatial division may be performed according to the height of the terminal 110.

As described with reference to FIG. 3, when the 3D MIMO scheme is used, the antennas arranged in the vertical direction can be softly tilted in the up / down direction by transmitting a signal with a phase difference, thereby physically tilting the antenna In addition to solving the problem of appearing shaded areas, it is possible to perform spatial division according to the height of the terminal.

2 through 3, the wireless communication system 100 has used a 3D MIMO system. Hereinafter, a description will be given of transmission and reception of a reference signal in the 3D MIMO system and transmission and reception of channel information corresponding thereto.

A MIMO system using a multidimensional antenna array may form a 3D or higher MIMO system (e.g., a 4D MIMO system). In the present invention, a 3D MIMO system refers to a MIMO system that performs precoding or beam forming using two or more phases defined independently of each other or defined on an orthogonal axis. When three or more phase components are used, it is defined as a 3D or higher MIMO system. Such a 3D or higher MIMO system can realize all the characteristics according to an embodiment of the present invention to be described later, and is described below based on a 3D MIMO system, but is not limited thereto.

The MIMO scheme is broadly classified into an open loop MIMO scheme that can operate without the base station 120 acquiring prior information about the channel and a closed loop MIMO scheme that uses the channel information of the base station 120 to learn and use the MIMO scheme . The closed loop MIMO scheme can perform more precise transmission control by using channel information. Thus, the closed loop MIMO scheme can obtain precoding gain and interference avoidance, which are not obtainable by the open loop MIMO scheme, such as higher precoding gain and interference avoidance. It is advantageous to obtain a gain. On the other hand, a separate feedback overhead is generated in order for the UE 110 to measure accurate channel information and to report the accurate channel information to the base station 120, and to allow the UE 110 to perform channel estimation for each transmit antenna or antenna port A reference signal overhead is generated.

4 is a diagram illustrating that the BS 120 transmits a reference signal 410 and receives channel information 420 including channel state information and channel quality information from the UE 110. FIG.

4, the base station 120 transmits a reference signal 410 to transmit and receive data between the terminal 110 and the base station 120, and the terminal 110 transmits a reference signal 410 using the reference signal 410, And the channel in each resource region defined on the frequency.

A particular signal or symbol can be inserted at regular or irregular intervals within the frequency-domain grid for channel estimation. At this time, the specific signal or symbol can be variously named as a reference signal, a reference symbol, a pilot symbol, or the like. In the present specification, the specific signal or symbol is referred to as a reference signal or a reference signal (RS), but the term is not limited thereto. Of course, the reference signal 410 is used not only for channel estimation but also for position estimation, transmission / reception of control information, transmission / reception of scheduling information, transmission / reception of feedback information, and the like necessary for wireless communication between the UE 110 and the Node B 120 .

There are various types of reference signals in downlink or uplink transmission, and new reference signals are defined and discussed for various purposes. For example, DM-RS (Demodulation RS), SRS (Sounding RS), and the like are used as reference signals that can be used in uplink signal transmission. The reference signals that can be used in downlink signal transmission include a cell-specific RS (CRS), an MBSFN RS, and a UE-specific RS. In addition, the CSI-RS (Channel State Index-Reference Signal) is used as a reference signal transmitted from the BS 120 in order to acquire channel state information (CSI) in the UE 110 in the downlink signal transmission . The CSI-RS is used for reporting CQI (Channel Quality Indicator) / PMI (Precoder Matrix Indicator) / RI (Rank Indicator).

Referring again to FIG. 4, each terminal 110 receives a reference signal 410 and estimates a channel. Each terminal 110 then feeds back the channel information 420 to the base station 120. At this time, the channel information may include channel state information, which is information on a propagation channel to the terminal itself, and channel quality information, which is information on measured or calculated channel capacity or channel quality. Meanwhile, the channel information 420 may include a channel rank or a Rank Indicator (RI), which is information on the number of layers used for downlink transmission to the UE.

At this time, the channel state information may include precoding information of the UE itself, which is suitable for the estimated channel, for example, an index for the precoding matrix or a Precoding Matrix Indicator (PMI). For example, in the case of MIMO that allows simultaneous access of n terminals, each of n terminals 110 may feed back channel state information, e.g., PMI, to the base station 120.

More specifically, when transmitting channel information through an index, the UE 110 determines an element that is determined to be most suitable for representing channel information among a plurality of elements included in a codebook, And transmits the index indicating the element to the base station 120 in the form of a channel information report.

In order to use the MIMO scheme, the BS 120 maps and transmits a plurality of antenna ports to which CRS or CSI-RS are mapped to different Tx antennas, and transmits the CRS or CSI- And acquires information on a MIMO channel generated by a plurality of Tx antennas and Rx antennas through CSI-RS measurement. After acquiring such information, the UE 110 calculates a matrix best suited for representing a channel matrix from a CSI feedback codebook, and indexes the calculated matrix using the RI and the PMI to the base station 120). Also, the CQI can be transmitted to the BS 120 as a report on channel quality. At this time, a wideband / subband CSI may be reported to the base station according to a feedback mode.

In a closed loop MIMO in a wireless communication system 100 using a multidimensional antenna array that performs precoding precisely using a plurality of transmit antennas or antenna ports, a MIMO scheme is used according to the accuracy of channel information reported by the UE 110 And the overall performance of the system.

When applying a scheme similar to CSI-RS-based channel estimation to 3D MIMO, a resource element (RE) for transmitting a reference signal (RS) is allocated to all transmit antennas or antenna ports, Horizontal direction) antenna set and assigning an RE for reference signal transmission can be used.

5 is an exemplary diagram of a CSI-RS antenna mapping for a base station 120 to transmit a reference signal in a two-dimensional antenna array.

FIG. 5 is a diagram illustrating a method of allocating a reference signal to each transmit antenna (antenna port) by using two RE allocation techniques for transmitting the reference signal (a technique of allocating a reference signal to all transmit antennas and a technique of transmitting a reference signal by selecting a domain- ) Is a reuse of the Rel-10/11 CSI-RS port. Based on the contents of Rel-11, the UE 110 can receive a plurality of CSI-RS resources, and each CSI-RS resource can include a maximum of 8 CSI-RS ports.

FIG. 5A illustrates an example of a method of representing reference signals for nine or more transmit antennas (antenna ports) by reusing Rel-11 CSI-RS resources. In FIG. 5 (a), the CSI-RS port index backward R # is an index for each of a plurality of CSI-RS resources received by the terminal 110. The CSI-RS port N (R0) in FIG. 5A can be represented as a new RS port N, and the CSI-RS port N (Rm) can be represented as a new RS port 8m + N .

 FIG. 5B illustrates a method of transmitting a reference signal through one set of representative antennas for each domain of the multi-dimensional antenna array. In the case of performing reference signal mapping and transmission by reusing Rel-11 CSI-RS resources, / CSI-RS resources (R0 and R1 respectively in Fig. 5) that are responsible for the horizontal / vertical domain are defined in the same subframe or in different subframes. In addition, the CSI-RS resource may be defined on the same subframe in the time axis, for example, when defining a CSI-RS resource on a subframe, a period or offset is defined by different subframes, or a period and offset are defined by the same parameter, Or on other subframes. The UE 110 can independently perform reception and channel estimation operations and CSI feedback operations for two domain RSs (two CSI-RS resources).

 In the present invention, a CSI-RS resource refers to pattern information about an RE to which a CSI-RS is mapped in each PRB pair (physical resource block pair) in a CSI-RS transmission permitted subframe Or a combination of all the information required to perform the CSI-RS reception including the information and information on the subframe in which the CSI-RS is transmitted, or a part of the information.

When the UE performs the CSI measurement and reporting using the CSI-RS as shown in FIG. 5, the UE 110 transmits channel information to the UE 110 according to whether the channel measurement is performed independently for each domain and whether the codebook is used. The process of doing so may be different.

6 and 7 are flowcharts illustrating an exemplary process in which the UE 110 receives CSI-RS and feeds back channel information through channel measurement.

6A is a flowchart of a first feedback method in which a reference signal is transmitted through all transmit antennas (antenna ports) and a UE 110 feedbacks channel information through a matrix index. Referring to FIG. 6A, the UE 110 receives a plurality of CSI-RSs (S602), and measures information on the multi-dimensional antenna array through the received CSI-RSs (S604). The terminal 110 may use a 3D channel matrix (when a 1D array is used for a receiving antenna) or a 4D channel matrix (when a 2D array is used for a receiving antenna) represented by a combination of a transmitting antenna and a receiving antenna (S606), and transmits an index (i.e., a matrix index) indicating the calculated channel matrix to the base station 120 (S608).

6B is a flowchart of a second feedback method for transmitting a reference signal through all transmit antennas (antenna ports) and for feedback of channel information through a channel parameter. Referring to FIG. 6B, the UE 110 receives a plurality of CSI-RSs (S652), and measures information on the multi-dimensional antenna array through the received CSI-RSs (S654). The terminal 110 calculates a channel parameter capable of representing a 3D channel expressed by a combination of a transmission antenna and a reception antenna (terminal antenna) (S656), and transmits the calculated channel parameter to the base station 120 (S658 ).

7A is a flowchart of a third feedback method in which the BS 120 transmits a reference signal independent of each domain and the MS 110 feedback channel information through a matrix index for each domain. Referring to FIG. 7A, the UE 110 independently receives a plurality of CSI-RSs for each domain (S702). The CSI-RS receives a plurality of CSI- Information about the vertical domain antenna array is measured (S704). The terminal 110 calculates a channel matrix suitable for representing the channel matrix for each domain in the codebook (S706), and transmits an index indicating the calculated channel matrix to the base station 120 (S708).

7B is a flowchart of a fourth feedback method in which the BS 120 transmits a reference signal independent of a domain and the UE 110 feeds back channel information based on a channel-specific channel parameter. Referring to FIG. 7B, the UE 110 receives a plurality of CSI-RSs independently for each domain (S752), and transmits the CSI-RSs to a horizontal domain through a plurality of received CSI- Information about the vertical domain antenna array is measured (S754). Then, the terminal 110 calculates a channel parameter suitable for representing a channel for each domain (S756), and transmits the calculated channel parameter to the base station 120 (S758).

In the case of the first feedback scheme in the wireless communication system 100 using a multidimensional antenna array, a very complex and large codebook considering various channel conditions must be generated when generating a codebook for CSI reporting. Furthermore, there is no guarantee that a codebook suitable for expressing such a complicated channel can be designed.

In the case of the second feedback method, since the channel parameter having a very complicated form should be reported, the feedback overhead may be a big problem.

In the case of the third feedback scheme, a scheme for independently measuring channel information for each domain is required, and a scheme for performing vertical domain channel measurement should be provided. In addition, , There is a problem of feedback overhead which requires reporting complex channel parameters.

One embodiment of the present invention proposes a reference signal transmission / reception scheme and a channel information transmission / reception scheme for performing multidimensional precoding through less signaling overhead and feedback overhead in a MIMO system using a multi-dimensional antenna array.

A method of estimating a channel using CSI-RS has been described above. In particular, a method of transmitting CSI-RS in a two-dimensional antenna array and feeding back channel information using the CSI-RS in a terminal has been described.

Hereinafter, a method of estimating a channel using another reference signal will be described in order to solve the above-mentioned problem of the method using the CSI-RS. These other reference signals can be newly defined using a new reference signal port. The reference signal for channel state estimation or another reference signal as described above may be defined as a new CSI-RS in the sense that it is distinguished from the existing CSI-RS.

To better understand the new CSI-RS, the existing CSI-RS will be explained in more detail, and the new CSI-RS will be described later.

Support for CSI-RS was introduced in Rel-10. The CSI-RS is used by the UE to acquire channel state information when the DM-RS is used for channel estimation. More specifically, the CSI-RS is used in transmission mode 9. CRS can also be used with CSI-RS to obtain channel state information.

One cell may be set to 1, 2, 4 or 8 CSI-RSs. A CSI-RS structure comprising a set of radio resource elements (REs) used for a CSI-RS in a resource block is associated with a CSI-RS number set in the cell. And it may be different from other cells.

8 is a diagram showing an example of mapping and mapping of a CSI-RS to a resource block pair.

Referring to FIG. 8, there are 40 configurable positions for a reference symbol of CSI-RS in one resource block pair as shown in FIG. 8, and a corresponding subset of REs in a given cell is as follows .

When there are two CSI-RSs in a cell, the CSI-RS consists of two consecutive reference symbols per resource block pair. The two CSI-RSs are distinguished by applying orthogonal cover codes (OCC) to the two reference symbols. Therefore, 20 different CSI-RS settings are possible based on 40 possible reference symbol positions.

If there are 4/8 CSI-RSs within a cell, the CSI-RSs are frequency multiplexed in pairs. Therefore, 10/5 different CSI-RS settings are possible for supporting 4/8 CSI-RS.

In the case where one CSI-RS is set, the structure is the same as that in the case where two CSI-RSs are set. There is a difference that only one OCC is used. The overhead of one CSI-RS in terms of the RE used is the same as that of two CSI-RSs.

In the time domain, the CSI-RS may be transmitted at a different period from a period of 5 ms (every 5 subframes) to a period of 80 ms (every 80 subframes). The overhead per CSI-RS at a cycle of 5ms is approximately 0.12%. It can be seen that in the same way, there is a smaller overhead in the longer period.

In the subframes in which the CSI-RS is transmitted, the CSI-RS is transmitted in all resource blocks in the frequency domain. In other words, one CSI-RS transmission covers the entire cell frequency band.

9 is a schematic diagram of a process of estimating and reporting channel state information using CSI-RS or CRS. The CSI-RS is cited as a conventional reference signal used for channel state estimation, but the CSI-RS can be used as a reference signal derived to supplement the CRS instead of the CSI-RS.

Referring to FIG. 9, a base station first generates a reference signal sequence for a CSI-RS, maps the generated CSI-RS to an antenna port, and maps the antenna port to a physical antenna.

Since the channel state must be measured for each antenna, a CSI-RS port (a total of four CSI-RS ports) is mapped to each of the four antennas shown in FIG.

For each CSI-RS transmitted in this manner, the reception antennas of the UE measure channel status information (CSI) and measure channel state information values (e.g., CQI, RI, PMI, etc.) And transmits channel state information including the channel state information to the base station.

A method of estimating a channel using a precoded CSI-RS as a new CSI-RS will be described below. In the sense that the reference signal for channel information estimation is precoded and transmitted, it is named Precoded CSI-RS, which is different from existing CSI-RS and is one of new CSI-RS.

10 is a block diagram of a precoded channel information estimation reference signal (precoded CSI-RS) transmitted and received in a wireless communication system 100 according to an embodiment of the present invention, and a precoded CSI- RS) index is fed back.

In FIG. 10, the BS 120 transmits a reference signal for channel information estimation using a different radio resource (RE or another RB or other subframe in the case of the same RE, or the same RE but uses a cover code coding can be performed to have different directivities for a plurality of reference signals using RE codes and codes divided into code divisions through a plurality of reference codes. Each of the plurality of reference signals described above is pre-coded to have different propagation directions and propagated through a plurality of physical antennas of a transmission end (base station 120).

Therefore, when the reference signals propagated in the propagation direction preferred by the terminal 110 are mapped to the radio resources to which the reference signals are mapped, the received power is measured to be high, and the terminal 110 measures propagation If the reference signal is mapped, the received power is low. And the received power is not measured for the reference signal propagated in the propagation direction in which the terminal 110 can not receive the signal.

The terminal 110 measures and compares the received power of each of the radio resources to which the reference signal propagated with different propagation directions has been mapped and recognizes the radio resource to which the reference signal indicating the proper direction is mapped to the terminal 110 And reports an index of radio resources suitable for the terminal 110 to the base station 120 so that the base station 120 can acquire suitable radio direction or precoding information for the terminal 110. [

Referring to FIG. 10, when transmitting a plurality of channel information estimation reference signals (new CSI-RS, precoded CSI-RS), each of the reference signals is divided into a vertical direction component And precoded so as to have different propagation direction. 10, the base station 120 transmits six reference signals 1010, 1011, 1012, 1013, 1014 and 1015. As can be seen in FIG. 10, each of the precoded CSI- do. The terminal 110 can measure the highest received power of the precoded CSI-RS 3 1013 propagated with the best propagation direction to the terminal 110. In this case, the terminal 110 transmits the precoded CSI- And may report the index for RS 3 to the base station 120. Through this process, the BS 120 can confirm information on the most preferred channel or the most suitable direction of propagation (precoding information) of the UE 110.

The first through fourth feedback methods described above with reference to FIGS. 6 through 7 must perform a complex operation in which the UE 110 measures a channel matrix. In this operation, the UE 110 transmits a plurality of channels or channel matrixes Measurements of amplitude and phase should be performed for each of the elements. In addition, a codebook search operation must be performed to express the measured channel matrix. In this case, depending on the codebook configuration, accurate CSI reporting may not be possible in some specific communication environments. A matrix having a large similarity to some channel matrices may not exist in the codebook because the size of the codebook is finite.

On the other hand, in the case of the feedback scheme using the precoded CSI-RS described with reference to FIG. 10, in consideration of the intra-region communication environment dedicated to each cell or each transmission terminal (the base station 120) A precoder to be used for the channel information measurement can be arbitrarily selected.

The technique proposed by the present invention may be a method of performing non-codebook based CSI reporting or a method of performing adaptive codebook based CSI reporting with low feedback overhead .

Additionally, the UE 110 may measure the received power for the wideband / subband and report the index of the Precoded CSI-RS for each band (wideband / subband). Whether the wide band or the sub-band is determined by the feedback mode defined by the base station 120 or by the transmission mode of the PDSCH which is a downlink information transmission channel. The feedback mode may be set separately for the precoded CSI-RS. In another embodiment, the CSI report measured through the CSI-RS or the CRS has already defined the wideband / subband report and the index -RS), it is possible to select a band to perform the index report in the same manner in the same mode based on the wideband / subband mode for CSI-RS or CRS-based CSI reporting, Directional CSI report, that is, the PMI / CQI / RI report may be a wide band or the precoded CSI-RS index report may be a subband, or the horizontal direction CSI report may be a subband or the index report may be a wide band It is also possible for the CSI report and the index report to report in different modes.

 Also, the UE 110 transmits PMI / RI / CQI measured through the existing CSI-RS or CRS and horizontal CSI-RS to the same PUCCH for reporting a horizontal domain CSI when reporting the precoded CSI- RI / CQI and the index with a time difference, and the last reported PMI / RI / CQI is transmitted to the UE through the Physical Uplink Control Channel (PUSCH) / Physical Uplink Shared Channel (PUSCH) The RI / CQI and the last reported precoded CSI-RS index are related to each other as information on the same channel.

In the present invention, the precoded CSI-RS is defined as an RS that has undergone a precoding operation for performing channel information reporting rather than channel measurement for PDSCH demodulation. The precoded CSI-RS means an RS transmitted to a plurality of UEs through precoding. In a subframe and a resource block in which a precoded CSI-RS is transmitted, each terminal can receive the precoded CSI-RS regardless of whether a PDSCH is received or not, estimates channel information through the precoded CSI-RS, report.

11 is a flowchart illustrating a process of transmitting and receiving channel information including information indicating a maximum received power reference signal RS transmitted / received by a precoded CSI-RS in a wireless communication system 100 according to an exemplary embodiment of the present invention.

11, the base station 120 precodes a plurality of reference signals using different matrices (S1110), maps the plurality of precoded reference signals to different radio resources, and transmits the mapped reference signals to the terminal 110 S1120).

The terminal 120 receives a plurality of reference signals mapped to different radio resources from the base station 120 (S1120), and measures a received power intensity for each of the plurality of reference signals (S1130).

In steps S1120 and S1130, a plurality of reference signals may be mapped to different radio resources in one resource block pair (PRB pair). This structure is a structure in which reference signals differently precoded in one PRB pair are mapped. In addition, the precoded CSI-RS may exist on all PRB pairs in a subframe in which transmission is set, or may exist on some PRB pairs. For example, it is possible to have only an even PRB pair, or only a PRB pair near the center frequency of the carrier frequency.

The terminal 120 transmits to the base station 120 channel information including information indicating a reference signal having the highest received power level among the plurality of received reference signals or transmits the channel information to the base station 120 in the ascending order or descending order The base station 120 transmits the channel information including the information indicating the reference signal to the base station 120 in step S1140. From the terminal 110, channel information including information indicating the largest reference signal or channel information including information indicating one or more reference signals determined in ascending or descending order of the received power intensity from the terminal 110 (S1140 ).

The terminal 120 may transmit channel information including information indicating the highest reference signal strength to the base station 120. However, the terminal 120 may further use other information than the received power intensity to transmit channel information The base station 120 may transmit channel information including information indicating a reference signal other than the reference signal having the largest received power level. In the latter case, the terminal 120 arranges the reference signals in ascending or descending order according to the received power intensity, and selects one preferred reference signal for two or more reference signals in descending order of the received power intensity according to the above- And transmit the channel information including the information indicating the selected reference signal to the base station 120.

In the wireless communication system 100, the base station 120 is a system using a multi-dimensional antenna array. In the step S1120 in which the base station 120 transmits a reference signal, And may be a beamforming matrix that allows the antenna array to transmit with different propagation directions in the vertical domain.

In the case of a communication system using MIMO, the channel characteristics between the transmission end and the reception end are largely determined by the physical location between the transmission end and the reception end and the distribution of the reflectors that generate the multipath. However, when the physical positions of the transmitting end / the receiving end and the distribution of the reflector are divided horizontally and vertically, the angular range is narrower in the vertical direction than in the horizontal direction, and the reflection or disturbance of the radio wave between the transmitting end / There is relatively little scatter. For this reason, it is possible to use the channel information through the precoded CSI-RS according to the embodiment of the present invention, which is simpler in structure, without using the channel estimation information through the CSI-RS for the vertical channel information feedback.

As a result, in the vertical direction, the base station 120 receives channel information using precoded CSI-RS precoded to have different propagation directions, and CRS (RI), a Precision Matrix Indicator (PMI), and a Channel Quality Information (CQI) as cell-specific transmission RSs having a cell-specific reference signal or a CSI- The channel information including at least one of the information of the channel information and the information of the channel information.

Referring to FIG. 11, in step S1120, the BS 120 transmits a cell-specific reference signal (CRS) or a CSI-RS (CSI-RS) (RI), a PMI (Precoder Matrix Indicator), and a CQI (Channel Quality Indicator) as horizontal domain channel estimation information through CRS or CSI-RS in step S1140 of receiving and transmitting channel information From the terminal 110, channel information including at least one piece of information.

The base station 120 can transmit a plurality of reference signals with the same power as the reference signals in the step S1120 of transmitting the reference signals. It is possible to measure the intensity of the received power according to the propagation path of the terminal 110 and report the optimal propagation direction or precoding information. Alternatively, when the base station is specialized for signal propagation in a specific vertical direction, a specific reference signal can be transmitted using a higher power than another reference signal. The UE does not receive information on whether the base station uses a higher power than the other reference signals for a specific reference signal and measures the received power of each reference signal.

The base station 120 may transmit a plurality of reference signals through some of the sets of vertical antennas constituting the antenna array in the step S1120 of transmitting the reference signals. This is a method for reducing the feedback overhead of the terminal 110 that feeds back the signaling overhead or channel information of the base station 120 transmitting the reference signal in the feedback of the channel information to all the antennas in the vertical direction.

In step S1140 of transmitting the channel information, the terminal 110 may transmit the index information of the reference signal to the base station 120 by including the index information of one or more reference signals in the descending order of the received power intensity in the channel information, The base station 120 may include the index information of the radio resource to which the signal is mapped in the channel information.

When the UE 110 receives the setup information for the precoded CSI-RS from the Node B 120 and can grasp the index of the precoded reference signal using different matrices, the UE 110 can feed back the corresponding index, If the set information can not be received or the index of the reference signal can not be grasped for another reason, a method of feeding back the index of the radio resource to which the reference signal is mapped can be used.

The UE 110 may transmit to the Node B 120 channel information including information indicating one reference signal having the highest received power level, and may transmit one or more (e.g., To the base station 120, channel information including information indicating the upper three reference signals. When the base station 120 receives information indicating the top three reference signals in the order of received power, the base station 120 can select and use information indicating one of the two reference signals. In the case of transmitting information indicating a plurality of reference signals to the base station as described above, the terminal may also report the information in a bitmap format.

Although some operations in the wireless communication system 100 according to the embodiment of the present invention described with reference to FIG. 11 have been described with respect to the transmitting or receiving end, the base station 120 and the terminal 110 operate as a transmitting end or a receiving end, respectively The opposite operation of the described operation can be performed at the receiving end or the transmitting end.

12 is a diagram illustrating an example of an information structure for transmitting and receiving RSs for channel estimation according to 2D / 3D MIMO and for feeding back channel information.

The wireless communication system base station 120 may use a 2D MIMO or a 3D MIMO scheme on the downlink. Accordingly, the BS 120 can transmit a reference signal for 2D MIMO channel measurement or a reference signal for 3D MIMO channel measurement so that the UE 110 can measure and report channel information necessary for using each MIMO technique. In addition, it is possible to notify the terminal 110 of the setting information about the reference signal transmission so that the terminal 110 can receive the reference signal.

Referring to FIG. 12, the BS 120 may include reference signal information 1210 for 2D MIMO and reference signal information 1220 for 3D MIMO as a field of setting information.

The BS 120 performs single or multiple CSI-RS transmissions for 2D MIMO channel measurements and also performs CSI-RS for 3D for horizontal domain channel measurement and CSI-RS for vertical MIMO channel measurements vertical domain < / RTI > channel measurement. Accordingly, the reference signal information 1230 for 3D MIMO may include CSI-RS information 1222 for 3D for horizontal channel measurement and precoded CSI-RS information 1224 for vertical channel measurement.

In addition, the BS 120 can arbitrarily select whether a technique applied to 2D / 3D MIMO or both techniques is used and transmit the selected technique to the UE 110 in a transmission mode format. For example, if the transmission mode (Tx mode) 1230 corresponds to 1 to N (a natural number of 1 or more) in FIG. 12, MIMO is not used. If the transmission mode 1230 is N + 1, 2D MIMO is used , And if the transmission mode is N + 2, it may indicate that 3D MIMO is used or any one of 2D / 3D MIMO is used. The transmission mode information may be transmitted from the base station 120 to the terminal 110.

In addition to the information on the transmission mode, the base station 120 may request an aperiodic CSI report to the terminal 110, which may be included in the aperiodic CSI reporting field 1240 and forwarded to the terminal 110 have.

The UE 110 extracts the CSI information through the channel estimation reference signal according to the reference signal information 1210 and 1220 for the 2D / 3D MIMO and the transmission mode information 1230 and reports it to the base station 120 .

The base station 120 transmits a reference signal for 2D MIMO channel estimation and a reference signal for 3D MIMO channel estimation as separate reference signals, and the terminal 110 performs 2D or 3D MIMO channel estimation through each reference signal. The 2D MIMO channel estimation is performed according to the Rel-10/11 scheme. In the case of 3D channel estimation, the RI, PMI, and CQI are measured through the reference signal for horizontal direction CSI estimation and the precoded CSI- To estimate the vertical direction CSI.

13 is a diagram for explaining that a precoded CSI-RS is mapped to different radio resources.

Referring to FIG. 13, the base station 120 transmits a plurality of reference signals precoded in order to form strong fields with different propagation directions in the vertical direction. A reference signal precoded to form a strong electric field with different propagation directions has a different radio resource (different REs, or the same REs, but a sequence is generated so as to be divided into orthogonal codes, or a mixture of these two resources ) And transmitted.

FIG. 14 is a flowchart illustrating a process of feeding back information indicating a reference signal having a high received power level, according to an embodiment of the present invention.

Referring to FIG. 14, the UE 110 measures the received power for a plurality of radio resources (S1402), and precodes the precoded CSI-RS mapped to the radio resource having the largest received power to the UE 110 Or may be recognized as a reference signal that has passed through a virtual channel suitable for the UE 110. [ In this manner, the terminal 110 calculates suitable vertical direction precoding information based on the received power (S1404).

If the UE 110 does not recognize the order or method in which each precoded CSI-RS is mapped to the radio resource (NO in S1406), the UE 110 transmits an index indicating a radio resource to which the precoded CSI- RS to the base station 120 in step S1408 and if the terminal 110 recognizes the order or method in which each precoded CSI-RS is mapped to the radio resource (yes in step S1406), the terminal 110 transmits the precoded CSI- RS to the BS 120 (S1410).

15 is a diagram illustrating an example in which a channel estimation RS is mapped to an antenna array in 3D MIMO.

15A illustrates a reference signal (CRS or CSI-RS) for horizontal channel CSI measurement and a reference signal (Precoded CSI) for vertical channel measurement using all the antennas constituting the antenna array by the base station 120 (CRS or CSI-RS) for the horizontal channel CSI measurement using all the antennas, and FIG. 15 (b) And transmits a reference signal (Precoded CSI-RS) for vertical channel measurement using the first set of vertical antennas of the antenna array. 15C shows a reference signal (CRS or CSI-RS) for horizontal channel CSI measurement and a reference signal (Precoded CSI-RS) for vertical channel measurement using some antenna sets constituting the antenna array Indicates transmission.

15 is a method suitable for use when the number of ports to be used for the precoded CSI-RS transmission is determined by the base station 120, and allocates one precoded CSI-RS port to each transmission antenna, To be transmitted with the same transmission power.

16 is a diagram showing that a reference signal is precoded and mapped to an antenna port.

Referring to FIG. 16, the BS 120 selects RS elements less than the number of precoded CSI-RS ports and performs precoding on each RS element to transmit the precoded CSI- . For example, if eight precoded CSI-RS ports are used, the base station 120 defines eight or fewer RS elements, and each RS element is mapped to eight precoded CSI-RS ports through precoding. Each precoded CSI-RS port is mapped back to the antenna port. A method for mapping the reference signals mapped to respective antenna ports to physical antennas can be arbitrarily determined by the base station 120. [

FIG. 17 is a diagram illustrating another example of an information structure for transmitting and receiving RSs for channel estimation according to 2D / 3D MIMO and feeding back channel information.

Comparing the example of the information structure of FIG. 17 with the example of the information structure of FIG. 10, it can be seen that reference signal information 1710 for 2D MIMO 1710 is used for the horizontal channel CSI measurement for 3D MIMO And reference signal information 1720 for 3D MIMO further includes information 1724 indicating a reference signal used for horizontal channel CSI measurement for 2D MIMO have.

Horizontal channel CSI estimation in 3D MIMO can use the same scheme as 2D MIMO, so the embodiment of FIG. 17 shows a method of displaying information about reference signals that can be commonly used in 2D MIMO and 3D MIMO.

Referring to FIG. 17, among the reference signals (CRS or CSI-RS) for a plurality of 2D MIMO channel CSI measurements, information on reference signals usable for 3D MIMO horizontal channel CSI measurement is referred to as reference signal information for 2D MIMO (A sub-field 1712 indicating whether to use for 3D MIMO horizontal channel CSI measurement) corresponding to reference numeral 1712 included in the sub-field 1710 included in the sub-field 1712.

(Information on a precoded CSI-RS for a 3D MIMO vertical channel measurement (location of a radio resource to which a precoded CSI-RS is mapped, information on a subframe in which a precoded CSI-RS is transmitted, (For example, how many times CSI-RS among the CSI-RSs the UE is set to receive, etc.) to transmit a reference signal (CRS or CSI-RS) to be used together for 3D MIMO horizontal channel CSI measurement (Information 1724 indicating a reference signal used for horizontal channel CSI measurement for 2D MIMO) corresponding to reference numeral 1724 and transmits the information to the terminal 110 together.

Additional aspects related to reference signal precoding at base station 120 are further discussed.

To support free precoded CSI-RS usage at the base station 120, a scheme may be considered in which the base station 120 transmits an arbitrary number of precode CSI-RSs. In this case, the base station 120 may define precoded CSI-RS ports that are smaller than the number of antennas constituting the vertical direction array and perform precoding when mapping each RS port to an antenna. In this case, the base station 120 can transmit precoded CSI-RS at an arbitrary number (the number of antenna ports) irrespective of the number of physical antennas.

When performing precoding on a reference signal, the base station 120 may use an arbitrary precoder, or may configure a precoding matrix by selecting some of the precoders having the following characteristics.

As a more general example, it can be expressed as the following equation.

In the above-described precoder example, the mapping rule between m and n can be defined separately. Also, the length K of v depends on the number of antenna ports or antennas used.

In order to solve the RS collision problem occurring in other UEs that do not receive a reference signal when allocating a radio resource used for the new precoded CSI-RS transmission, The CSI-RS or non-zero power CSI-RS resource allocation scheme may be reused.

The reference signal transmission / reception method and the channel information transmission / reception method according to an embodiment of the present invention have been described above. Hereinafter, a configuration of a BS 120 and a UE 110 according to an embodiment of the present invention will be described. The base station 120 and the terminal 110 may perform both the reference signal transmission / reception and the channel information transmission / reception method described above.

18 is a block diagram of a base station 120 in accordance with an embodiment of the present invention.

18, the base station 120 includes a controller 123 for precoding a plurality of reference signals in different matrices, a transmitter 121 for mapping a plurality of precoded reference signals to different radio resources and transmitting the same to different terminals A receiving unit 122 for receiving channel information from a terminal, and the like. The channel information received by the receiving unit 122 includes information obtained by aligning the received power intensities of the plurality of reference signals measured by the terminal in ascending or descending order.

The base station 120 may be a system using a multi-dimensional antenna array. In this case, the control unit 121 may be a beamforming matrix for transmitting a plurality of reference signals with different propagation directions in the vertical direction of the antenna array A plurality of reference signals can be precoded. In the base station 120, the transmitter 121 can transmit a plurality of precoded reference signals through a set of antennas among a set of vertical antennas constituting the antenna array.

The transmitter 121 can transmit a plurality of precoded reference signals with the same power.

The information indicating one or more reference signals received by the receiving unit 122 may be index information of a reference signal or index information of a radio resource to which a reference signal is mapped.

When the transmitting unit 121 further transmits a cell-specific reference signal (CRS) or a CSI-RS (channel state information reference signal) to the terminal 110, the receiving unit 122 transmits the CRS or CSI- from the UE 110, channel information including at least one of a Rank Indicator (RI), a Precursor Matrix Indicator (PMI), and a Channel Quality Indicator (CQI) as horizontal domain channel estimation information.

19 is a block diagram of a terminal 110 according to an embodiment of the present invention.

19, a UE 110 includes a receiving unit 112 for receiving a plurality of reference signals mapped to different radio resources from a base station, a control unit 113 for measuring a received power intensity for each of a plurality of reference signals, And a transmitter 111 for transmitting to the base station channel information including information indicating one or more reference signals in descending order of the received power intensity among the plurality of reference signals.

In the receiver 112, a plurality of reference signals may be mapped to different radio resources in one resource block pair (PRB pair) and transmitted from the base station. This structure is a structure in which reference signals differently precoded in one PRB pair are mapped.

The transmitting unit 111 uses the index information of the reference signal or the index information of the radio resource to which the reference signal is mapped, as the information indicating the reference signal, to the information indicating one or more reference signals in descending order of the received power intensity And transmit it to the base station 120.

When the receiving unit 112 further receives a cell-specific reference signal (CRS) or a channel state information reference signal (CSI-RS), the transmitting unit 111 transmits the CRS or CSI- ) Channel information including at least one of a Rank Indicator (RI), a Precursor Matrix Indicator (PMI), and a Channel Quality Indicator (CQI) as channel estimation information to the base station 120.

When the base station 120 is a system using a multidimensional antenna array in the wireless communication system 100 including the terminal 110, the receiving unit 112 may include a beamforming matrix for causing the antenna array to have different propagation directions in the vertical direction, A plurality of reference signals precoded by a plurality of antennas.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. That is, within the scope of the present invention, all of the components may be selectively coupled to one or more of them. In addition, although all of the components may be implemented as one independent hardware, some or all of the components may be selectively combined to perform a part or all of the functions in one or a plurality of hardware. As shown in FIG. The codes and code segments constituting the computer program may be easily deduced by those skilled in the art. Such a computer program can be stored in a computer-readable storage medium, readable and executed by a computer, thereby realizing an embodiment of the present invention. As a storage medium of the computer program, a magnetic recording medium, an optical recording medium, or the like can be included.

It is also to be understood that the terms such as " comprises, "" comprising," or "having ", as used herein, mean that a component can be implanted unless specifically stated to the contrary. But should be construed as including other elements. All terms, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, unless otherwise defined. Commonly used terms, such as predefined terms, should be interpreted to be consistent with the contextual meanings of the related art, and are not to be construed as ideal or overly formal, unless expressly defined to the contrary.

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 (20)

A method for a base station in a wireless communication system to transmit a reference signal and to receive channel information,
Mapping a plurality of reference signals precoded in different matrices to different radio resources and transmitting the same to a mobile station; And
A channel information including information indicating a reference signal having a strongest received power at the terminal among the plurality of reference signals or one or more reference signals determined according to a descending order or an ascending order of a received power intensity at the terminal Receiving channel information including information from the terminal
And transmitting the reference signal.
The method according to claim 1,
In the wireless communication system, the base station is a system using a multi-dimensional antenna array,
In the transmitting step,
Wherein the different matrix is a beamforming matrix for transmitting the plurality of reference signals with different propagation directions in a vertical domain of the antenna array. .
3. The method of claim 2,
In the transmitting step,
Wherein the plurality of reference signals are transmitted through a part of antenna sets of vertical antenna sets constituting the antenna array.
The method according to claim 1,
In the transmitting step,
Wherein the plurality of reference signals are transmitted at the same power.
The method according to claim 1,
In the receiving step,
Wherein the information indicating the reference signal is index information of the reference signal or index information of a radio resource to which the reference signal is mapped.
The method according to claim 1,
In the transmitting step,
A cell-specific reference signal (CRS) or a channel state information reference signal (CSI-RS)
In the receiving step,
The channel information includes at least one of a Rank Indicator (RI), a Precursor Matrix Indicator (PMI), and a Channel Quality Indicator (CQI) as horizontal domain channel estimation information through the CRS or the CSI- From the user equipment (UE) terminal.
A method for a terminal to receive a reference signal and transmit channel information in a wireless communication system,
Receiving a plurality of reference signals mapped to different radio resources in a physical resource block pair from a base station;
Measuring a received power intensity for each of the plurality of reference signals; And
The channel information including information indicating the reference signal having the largest received power intensity among the plurality of reference signals or channel information including information indicating one or more reference signals determined in ascending order or ascending order of the received power intensity, To the base station
And receiving the reference signal and transmitting the channel information.
8. The method of claim 7,
In the transmitting step,
Wherein the information indicating the reference signal is index information of the reference signal or index information of a radio resource to which the reference signal is mapped.
8. The method of claim 7,
In the receiving step,
Further receives a cell-specific reference signal (CRS) or a channel state information reference signal (CSI-RS)
In the transmitting step,
And further comprising at least one of a RI (Rank Indicator), a PMI (Precoder Matrix Indicator) and a CQI (Channel Quality Indicator) as horizontal domain channel estimation information estimated through the CRS or the CSI- And transmits the channel information to the base station.
8. The method of claim 7,
In the wireless communication system, the base station is a system using a multi-dimensional antenna array,
In the receiving step,
And receiving the plurality of reference signals precoded by a beamforming matrix having different propagation directions in a vertical domain of the antenna array. Transmission method.
A base station for transmitting a reference signal and receiving channel information in a wireless communication system,
A controller for precoding each of a plurality of reference signals using different matrices;
A transmitter for mapping the plurality of precoded reference signals to different radio resources and transmitting the same to a mobile station; And
The channel information including the information indicating the highest received signal strength of the terminal among the plurality of reference signals or the information indicating one or more reference signals determined according to the descending order or ascending order of the received signal power intensity at the terminal For receiving channel information from the terminal
/ RTI >
12. The method of claim 11,
In the wireless communication system, the base station is a system using a multi-dimensional antenna array,
In the control unit,
Wherein the different matrices are beamforming matrices that allow the plurality of reference signals to be transmitted with different propagation directions in a vertical domain of the antenna array.
13. The method of claim 12,
The transmitter may further comprise:
And transmits the plurality of reference signals through a set of antennas among a set of vertical antennas constituting the antenna array.
12. The method of claim 11,
The transmitter may further comprise:
And transmits the plurality of reference signals with the same power.
12. The method of claim 11,
In the receiving unit,
Wherein the information indicating the reference signal is index information of the reference signal or index information of a radio resource to which the reference signal is mapped.
12. The method of claim 11,
The transmitter may further comprise:
A cell-specific reference signal (CRS) or a channel state information reference signal (CSI-RS)
The receiver may further comprise:
The channel information includes at least one of a Rank Indicator (RI), a Precursor Matrix Indicator (PMI), and a Channel Quality Indicator (CQI) as horizontal domain channel estimation information through the CRS or the CSI- From the terminal.
An apparatus for receiving a reference signal and transmitting channel information in a wireless communication system,
A receiver for receiving a plurality of reference signals mapped to different radio resources in a physical resource block pair from a base station;
A control unit for measuring a received power intensity with respect to each of the plurality of reference signals; And
The channel information including information indicating the reference signal having the largest received power intensity among the plurality of reference signals or channel information including information indicating one or more reference signals determined in ascending order or ascending order of the received power intensity, To the base station
/ RTI >
18. The method of claim 17,
In the transmitter,
Wherein the information indicating the reference signal is index information of the reference signal or index information of a radio resource to which the reference signal is mapped.
18. The method of claim 17,
The receiver may further comprise:
Further receives a cell-specific reference signal (CRS) or a channel state information reference signal (CSI-RS)
The transmitter may further comprise:
And further comprising at least one of a RI (Rank Indicator), a PMI (Precoder Matrix Indicator) and a CQI (Channel Quality Indicator) as horizontal domain channel estimation information estimated through the CRS or the CSI- And transmits the channel information to the base station.
18. The method of claim 17,
In the wireless communication system, the base station is a system using a multi-dimensional antenna array,
The receiver may further comprise:
And receives the plurality of reference signals precoded by a beamforming matrix having different propagation directions in a vertical domain of the antenna array.

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