KR101556154B1 - Method for transmitting and receiving signals in the Multi-Input Multi-Output wireless communication system - Google Patents

Abstract

The present invention relates to a signal transmission method for feedback overhead reduction, in which a receiving end estimates a first matrix using channel information of a received signal, feeds back identification information of the first matrix to a transmitting end in units of a first period, Acquiring a second matrix constituting a precoding matrix in which channel performance is optimized through multiplication with the first matrix, and feeding back the identification information of the second matrix to the transmitter in units of a second period, 1 matrix and the second matrix, and the signal is received using the precoding matrix generated through the multiplication of the first matrix and the second matrix.

MIMO, codebook, precoding, eigenvalue decomposition

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for transmitting and receiving signals in a multi-input multi-output communication system,

The present invention relates to a method for transmitting and receiving signals using precoding in a wireless communication system using a multiple-input multiple-output scheme, and more particularly, to a method for transmitting and receiving signals using two precoding matrices And a method for transmitting and receiving signals through the same.

Recently, the demand for fast wireless communication service is rapidly increasing due to the generalization of information communication service, the introduction of various multimedia services, and the emergence of high quality services. In order to proactively cope with this, the capacity of the communication system should be increased above all. In order to increase the communication capacity in the wireless communication environment, there are a method of newly finding an available frequency band and a method of improving efficiency of limited resources have. In the latter method, a plurality of antennas are mounted on a transceiver to obtain a diversity gain by further securing a spatial area for resource utilization, or to increase data transmission capacity by transmitting data in parallel through each antenna, MIMO transmission / reception technology is actively being developed with great attention recently.

In short, MIMO is a reduction of 'Multi-Input Multi-Output', so far it has not used one transmit antenna and one receive antenna, so it adopts multiple transmit antennas and multiple receive antennas to improve transmit and receive data efficiency. How can you say. That is, a technique for increasing the capacity or improving the performance by using multiple antennas at the transmitting end or the receiving end of the wireless communication system. Hereinafter, 'MIMO' will be referred to as 'multiple antennas'.

In summary, the multi-antenna technique is a technique of collecting a piece of fragmentary data received from various antennas, without relying on a single antenna path, in order to receive a whole message. This can improve the speed of data transmission in a particular range or increase the system range for a particular data rate.

Next generation mobile communication requires much higher data rate than existing mobile communication, so efficient multi-antenna technology is expected to be necessary. In such a situation, MIMO communication technology is a next generation mobile communication technology that can be widely used for mobile communication terminals and repeaters, and is attracting attention as a technology capable of overcoming transmission limitations of other mobile communication due to limitations due to expansion of data communication have.

Meanwhile, a multi-antenna (MIMO) technique using a plurality of antennas at both the transmitter and the receiver of various transmission efficiency enhancement technologies currently being studied is a method capable of dramatically improving communication capacity and transmission / reception performance without additional frequency allocation or power increase Which is currently receiving the greatest attention.

The MIMO technique increases the channel capacity within a limited frequency resource by using multiple antennas. The MIMO technique provides a channel capacity proportional to the number of antennas in theory by using a plurality of antennas when the scattering environment is excellent.

1 is a block diagram of a general multi-antenna (MIMO) communication system.

As shown in FIG. 1, if the number of transmission antennas is increased to N _{T and the} number of reception antennas is increased to N _R simultaneously, unlike the case where a plurality of antennas are used only in a transmitter and a receiver, The transmission capacity is increased, so that the transmission rate can be improved and the frequency efficiency can be remarkably improved. The transmission rate in accordance with the increase of the channel transmission capacity may theoretically increase by multiplying the maximum transmission rate Ro when using one antenna by the following rate of rate increase Ri.

That is, for example, in a MIMO communication system using four transmit antennas and four receive antennas, the transmission rate can be four times the theoretical one in comparison with the single antenna system.

Since the theoretical capacity increase of such a multi-antenna system has been proved in the mid-90s, various technologies have been actively researched to improve the actual data transmission rate. Some of these technologies have already been developed for 3G mobile communication and next generation wireless LAN, and the like.

The research trends related to multi-antennas to date include information theory studies related to calculation of multi-antenna communication capacity in various channel environments and multiple access environments, research on wireless channel measurement and modeling of multi-antenna systems, and improvement of transmission reliability and transmission rate And research on space-time signal processing technology for various applications.

In the above-described multi-antenna system, the transmitter performs precoding on the transmission data and transmits the precoded data. The receiver receives the signal using the precoding vector used by the transmitter.

On the other hand, the precoding scheme includes a codebook based precoding scheme used when feedback information is finite in a closed loop system, and a scheme of quantizing and feedbacking channel information.

In the codebook-based precoding, a signal-to-noise ratio (SNR) gain is obtained by feeding back the precoding metric index (PMI) of a precoding matrix already known to the transmitting and receiving end to the transmitting end. The precoding vector for performing the precoding described above uses any one of precoding vectors predefined in the form of a codebook on both sides of the transmitting and receiving end. At this time, depending on whether the precoding vector used by the transmitting side requires feedback information from the receiving side, the transmission method of the transmitting side is divided into an open-loop transmission method and a closed-loop transmission method .

In the case of the open loop transmission scheme, the transmitting side selects a precoding vector without feedback information on the receiving side and transmits the signal. In the case of the closed loop transmission scheme, on the receiving side, a specific precoding vector among the predefined codebooks is indicated according to the received signal, and channel information or the like is fed back. On the transmission side, the signal is transmitted using the feedback signal do.

In the closed-loop scheme, the feedback information on the receiving side needs to use a large information size to represent a precoding matrix to be used among all the precoding matrices, thereby causing overhead.

On the other hand, in the MIMO technique using multiple antennas, the space and the area where the antennas can be installed are limited, and the spacing between the antennas has a great influence on the system performance. As the spacing between the antennas narrows, the radio channels have a high correlation to each other. If the antennas have the same polarization, the radio channels have a very high correlation, Thereby reducing the data transmission rate. Accordingly, there is a need for a method of constructing a precoding matrix in a MIMO system with low complexity and high performance, when antennas have multiple polarizations in order to increase the channel capacity while reducing the area where a plurality of antennas are installed.

Also, in the MIMO scheme, as the overhead increases in the precoding feedback, the signal transmission time increases and the system efficiency decreases. In addition, since the transmission and reception performance is greatly influenced by the precoder codebook design method, it is possible to reduce the amount of feedback data, and to reduce the complexity and the performance of the MIMO system It is important to construct a coding matrix.

According to an aspect of the present invention, there is provided a method for transmitting / receiving a signal using precoding in a multi-input multiple-output (MIMO) wireless communication system, And a method of transmitting and receiving signals through the precoding matrix.

According to an aspect of the present invention, there is provided a method of receiving a signal using a multi-antenna method, the method comprising: calculating a first matrix using channel information of a received signal; And a second matrix constituting a precoding matrix in which a channel performance is optimized through multiplication with the estimated first matrix, from a predetermined second matrix set, The method comprising the steps of: feeding back the identification information of the first matrix to the transmitting end in units of a second period; and receiving a signal from the transmitting end using the precoding matrix generated through the multiplication of the first matrix and the second matrix, Wherein the first matrix comprises a first type matrix comprising a Discrete Fourier Transform (DFT) matrix and a phase-shift matrix, And a second type matrix in the form of a matrix for a dual polarized antenna having a first type matrix as a component.

At this time, it is preferable that the first period is different from the two periods.

Here, the first matrix identification information feedback step may include: calculating the first matrix through an eigenvalue decomposition of a channel correlation matrix of the received signal; DFT matrix and the phase shift matrix, and transmitting identification information corresponding to a phase value of the phase shift matrix as identification information of the first matrix. And the DFT matrix and the second matrix set are predetermined between the transmitting end and the receiving end.

와 같은 수학식을 이용하여 M(Q_iV_n)값이 최대가 되는 V_n값의 식별 정보를 상기 제 2 행렬의 식별정보로서 피드백하는 것이 바람직하며, 이때, 상기 Q_i는 상기 제 1 행렬에 대한 코드북에서 i번째 행렬을, 상기 V_n은 상기 제 2 행렬 집합에서 n번째 행렬을, 상기 M은 채널 성능에 따른 소정의 메트릭(metric)을 나타낸다. The step of feeding back the second matrix identification information may include:

Using Equation by M (Q _i V _n) value is preferable to feed back the identification information of the V _n value is maximized as the identification information of the second matrix, such as, when this occurs, the Q _i are the first matrix Where V _n denotes an n-th matrix in the second matrix set, and M denotes a predetermined metric according to channel performance.

In a method in which a receiving terminal using the multi-antenna scheme receives a signal, the receiving and transmitting sides may be a terminal or a base station, respectively.

A method for transmitting a signal using a multi-antenna scheme according to another embodiment of the present invention includes the steps of receiving identification information of a first matrix from a receiver in units of a first period, Receiving identification information of a second matrix constituting a precoding matrix in which a channel performance is optimized through multiplication with a first matrix from a receiver, generating the precoding matrix generated by multiplying the first matrix by the second matrix, And transmitting the precoded signal to the receiver, wherein the first matrix comprises a discrete Fourier transform (DFT) matrix and a phase-shift matrix consisting of a phase-shift matrix 1 type matrix and a second type matrix in the form of a matrix for a dual polarization antenna having the first type matrix as a component All.

And the first period is different from the second period.

Here, the identification information of the first matrix may be obtained by multiplying a specific first matrix calculated through an eigenvalue decomposition of a channel correlation matrix for a received signal at the receiving end with the DFT matrix and the phase shift matrix , It is received as identification information corresponding to the phase value of the phase shift matrix.

와 같은 수학식을 이용하여 M(Q_iV_n)값이 최대가 되는 V_n값의 식별 정보로서 수신되는 것이 바람직하며, 이 때 상기 Q_i는 상기 제 1 행렬에 대한 코드북에서 i번째 행렬을, 상기 V_n은 상기 제 2 행렬 집합에서 n번째 행렬을, 상기 M은 채널 성능에 따른 소정 메트릭(metric)을 나타낸다.Wherein the identification information of the second matrix indicates a specific second matrix within a predetermined second matrix set,

Is preferably received as identification information of a value of V _n that maximizes the value of M (Q _i V _n ), where Q _i is an i-th matrix in the codebook for the first matrix , V _n denotes an n-th matrix in the second matrix set, and M denotes a predetermined metric according to channel performance.

It is preferable that in the method of transmitting a signal using the multi-antenna scheme, the DFT matrix and the second matrix set are determined in advance between the transmitting end and the receiving end, and the receiving end is a terminal, Base station. The receiving side may be a base station, and the transmitting side may be a terminal.

It is possible to construct the precoding matrix more efficiently through the feedback method in two stages in the multi-antenna system disclosed in the above-described embodiments of the present invention. In addition, system efficiency can be optimized by reducing overhead during signal transmission.

The precoding matrix may be adaptively changed according to the state of the channel. As in the embodiments of the present invention, the precoding matrix is obtained by dividing a first matrix obtained by eigen-decomposing a correlation matrix of a channel into a predetermined DFT matrix and a phase shift matrix And the feedback phase can be fed back to reduce the feedback overhead.

Further, the present invention provides a signal transmission method using a precoding matrix for a multi-polarization multiple-input multiple-output system corresponding to a change in polarization direction of transmission antennas more flexibly using a rotation matrix when the polarization direction of transmission antennas is rotated can do.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following detailed description, together with the accompanying drawings, is intended to illustrate exemplary embodiments of the invention and is not intended to represent the only embodiments in which the invention may be practiced. For example, the following description illustrates a specific example applied to a 3GPP LTE (Long Term Evolution) system for the sake of clarity, but the present invention is not limited to 3GPP LTE systems, The wireless communication system can be applied by the same principle. In the following description, the base station may be replaced with other terms such as 'Node B', 'eNode B', 'BS', etc. and the terminal may be applied to a user equipment (UE), a mobile station The term can be replaced and applied. Communication systems are widely deployed to provide various communication services such as voice, packet data, and the like. This technique can be used for a downlink or an uplink. The downlink means communication from the base station to the terminal, and the uplink means the communication from the terminal to the base station.

The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, those skilled in the art will appreciate that the present invention may be practiced without these specific details. In some instances, well-known structures and devices are omitted or shown in block diagram form around the core functions of each structure and device in order to avoid obscuring the concepts of the present invention. In the following description, the same components are denoted by the same reference numerals throughout the specification.

In a multi-antenna system, a signal is adaptively transmitted according to a channel state. The transmitter performs precoding on transmission data and transmits the signal. The receiver receives a signal using a precoding vector used in the transmitter.

In Equation (2), P is a precoder or a beamformer, which is a precoding matrix adaptively changeable according to a channel state, and z represents a signal actually transmitted. The precoding matrix P varies depending on how much the transmitter knows the state of the channel.

2 is a diagram schematically illustrating a flow of constructing a precoding matrix according to an embodiment of the present invention and transmitting a signal using the precoding matrix.

FIG. 2 illustrates an example in which a transmitter is a base station (eNode B) and a receiver is a terminal (UE). However, in the case of a communication system capable of applying a MIMO scheme to an uplink, The uplink signal transmission / reception can be applied as it is.

According to the example shown in FIG. 2, a terminal (receiving end) receiving a downlink signal from a base station (transmitting end) can acquire downlink channel information through the downlink signal. Using the downlink channel information thus obtained, the UE can estimate the first matrix through eigenvalue decomposition or the like of the channel correlation matrix, and then the UE calculates the first matrix, which is previously determined between the transmitting and receiving ends The feedback overhead can be reduced by feeding back only the phase shift value to the base station in the first period T _Q by dividing the phase shift matrix into a DFT (Discrete Fourier Transform) matrix and a phase shift matrix. The first matrix estimation and feedback will be described in more detail with reference to FIG. 3. Hereinafter, in the absence of confusion, the first matrix is denoted by Q. FIG.

Meanwhile, the UE obtains a second matrix constituting a precoding matrix whose channel performance is optimized through multiplication with Q, from a predetermined second matrix set (for example, a codebook in the IEEE 802.16e system) as the identification information a second period (T _v) units can be fed back to the base station. If there is no confusion below, the second matrix is denoted by V. [

The BS receiving the Q and V information from the UE may precode and transmit the downlink signal using the precoding matrix P generated from Q * V (S220). In the example of FIG. 2, the first period (T _Q ) for transmitting the identification information of the Q matrix is longer than the second period (T _V ) for transmitting the identification information of the V matrix. However, May be set longer than one cycle.

Hereinafter, the process of calculating the first matrix at step S210 will be described in more detail.

3 is a flowchart illustrating a process of calculating the first matrix according to an embodiment of the present invention.

In step S320, the receiving end acquires the channel information of the downlink signal and calculates the first matrix by eigenvalue decomposition of the channel correlation matrix in step S320. The following equation (3) can be used for the calculation of the first matrix.

Here, R _t represents a correlation matrix of the channel, Q represents the first matrix, and Q ^H represents a conjugate transpose matrix (Q ^H = (Q ^T ) ^* ) of the Q matrix.

Since each element of the first matrix is a complex number, a large amount of overhead may be required in the feedback process for obtaining the precoding matrix, and an infinite number of first matrix codebooks may be obtained. Therefore, a method of appropriately quantizing the first matrix required in the codebook of the first matrix is required. To this end, in the present embodiment, the calculated first matrix is divided into a DFT matrix and a phase shift matrix, It is proposed that the phase value of the phase shift matrix corresponding to the first matrix calculated in step S320 is calculated (S330). Thereafter, the receiving end may transmit the calculated phase value or the identification information corresponding to the phase value to the transmitting end as the identification information of the first matrix (S340). Here, the following equation (4) can be used when constructing the i-th first matrix.

으로 나타내고, 인덱스 i는 0에서 N-1 사이의 값이며, N은 2n 이다. 여기서 위상은 i번째 위상천이각도를 의미하고, 수신신호의 세기를 최대로 할 수 있도록 임의로 선택할 수 있는 값이다. 상기 채널상관행렬의 고유치 분해를 통한 산정된 제 1 행렬의 코드북에 속한 행렬 값과 DFT 행렬 및 위상 이동 행렬의 곱으로 산정한 제 1 행렬이 가장 비슷하게 구성될 수 있도록 위상을 선택하는 것이 바람직하다.Where P _s (φ _i ) denotes a phase shift matrix, W denotes a DFT matrix, and when the first matrix Q _i is quantized to n bits,

, Index i is a value between 0 and N-1, and N is 2n. Here, the phase means an i-th phase shift angle, and is a value that can be arbitrarily selected so as to maximize the strength of the received signal. It is preferable to select a phase such that a first matrix calculated by multiplying a matrix value belonging to a codebook of a first matrix calculated through eigenvalue decomposition of the channel correlation matrix by a DFT matrix and a phase shift matrix can be structured to be most similar.

After the phase value indicating the first matrix is calculated as described above, the information corresponding to this phase can be fed back to the transmitting end in units of the first period as the identification information of the first matrix.

In another embodiment of the present invention, one step may be added to the example of FIG. 2 in order to normalize the power of the transmitting end. For example, suppose that a function that makes 'orth (X)' be an orthonormal X matrix. Instead of transmitting a signal using Q * V at the transmitting end, Lt; / RTI >

In the example of FIG. 2, in step S330 of calculating the first matrix by the product of the DFT matrix and the phase shift matrix according to the present embodiment, W, which is a DFT matrix, is a number of transmit antennas in a predetermined set between a transmitter and a receiver , Whether or not to use a single polarization, and polarization direction.

For example, if there are two single-polarization antennas at the transmitting end, the first matrix may be expressed by Equation (5).

And Equation (5) is constructed on the basis of the case where two single-polarized antennas of the transmitting end are provided parallel to the reference plane in a vertically direction. That is, as described above, the phase shift matrix (P _2x2 ) of Equation (5) is set such that the product of the first matrix listed in the first matrix codebook obtained through the eigenvalue decomposition of the channel correlation matrix is similar to the DFT matrix and the phase shift matrix . In this case, it is possible to select a first matrix that is easier than selecting the first matrix directly from a codebook having infinite candidates for the first matrix, and to prevent an increase in overhead required in this process And the increase in signal transmission time can be solved.

As another example, if there are four single-polarization antennas at the transmitting end, the first matrix may be expressed as Equation (6).

Similarly, Equation (6) is constructed on the basis of the case where four single-polarized wave antennas of the transmitting end are provided parallel to the reference plane in a vertiacl direction.

The structure of the array of transmit antennas can be variously implemented. That is, the codebook of the first matrix may have a good performance not only in the case of a single polarization, but also in the case of multiple polarization.

When the transmitting end antenna is a dual polarized antenna, the transmission antennas are orthogonal to each other. Therefore, the polarization directions of the signals transmitted from the transmission antennas are orthogonal to each other.

4 is a diagram schematically showing a case where a dual-polarization antenna is provided in a transmitting end according to another embodiment of the present invention.

Referring to FIG. 4, two transmission antennas 411 and 412 corresponding to one polarization direction at a reference numeral 410 are installed in a vertical direction with respect to a reference plane, and two transmission antennas 411 and 412 corresponding to one polarization direction The transmitting antennas 413 and 414 may be installed horizontally with respect to the reference plane. Since the transmission antennas are orthogonal to each other, the polarization directions of the signals transmitted from the transmission antennas are orthogonal to each other.

Also, as indicated by reference numeral 420, the transmission antennas corresponding to one polarization direction are installed in the + 45 ° direction with respect to the reference plane, and the transmission antennas corresponding to the other polarization direction are oriented in the -45 ° direction with respect to the reference plane May be installed. The signals transmitted from the two transmit antennas 421 and 422 and the other two transmit antennas 423 and 424 are orthogonal to each other.

If the polarization direction of the transmit antennas is rotated by a certain angle relative to the reference plane, the precoding matrix must be beamformed using the rotated rotation precoding matrix, where the rotation precoding matrix is the rotation matrix of the first matrix . ≪ / RTI > That is, a rotating first matrix and a rotated precoding matrix may be generated by multiplying a first matrix by a rotation matrix.

The size of the precoding matrix may be determined according to the number of transmission antennas having the same polarization direction. When four dual polarized antennas are used, the first matrix selected from the codebook of the first matrix can use Equation (6) as well as the matrix as shown in FIG.

FIG. 5 is a diagram illustrating a first matrix in a dual polarized antenna type MIMO system according to an embodiment of the present invention. Referring to FIG.

Referring to FIG. 5, the first matrix is shown when the number of transmission antennas is 4 and the number of polarization directions of transmission antennas is 2. A 510 and B 520 are a single polarization matrix, and two 0s 530 and 540 represent a zero matrix.

Since the number of polarization directions of the transmission antennas is '2', there are two diagonal blocks and two remaining blocks. A (510) and B (520), which are single polarization pre-coding matrices, are assigned to the diagonal blocks, respectively. The remaining blocks are assigned zero matrixes 530 and 540, respectively. At this time, the sizes of A (510) and B (520) may be determined according to the number of transmission antennas having the same polarization direction. For example, assuming that the polarization direction of the transmission antenna is the x direction and the polarization direction of the remaining two transmission antennas is the y direction, A 510 may be a single polarization matrix corresponding to the polarization direction in the x direction, and x The number of the transmission antennas corresponding to the polarization direction of the A direction 510 is two, so that the number of rows and columns of the A 510 can be two. Similarly, the number of rows and columns of B 520 may be two.

Equation (7) shows an embodiment of a first matrix for a dual polarized antenna.

The U matrix in Equation (7) is an additional matrix required when the first matrix should have a constant modulus characteristic. If the first matrix does not need to have a constant coefficient characteristic, the U matrix may be represented by a unit matrix I in which all the elements on the main diagonal line are 1 and the remaining elements are 0. If the dual polarized antenna rotates by 45 degrees, the U matrix may be represented by Equation (8) such that the first matrix has a constant coefficient characteristic.

If the number of dual polarization antennas is eight, the first matrix may be represented by a product of two 4 × 4 matrixes having two diagonal blocks as shown in FIG.

As described above, the first matrix includes not only a first type matrix formed by multiplying a DFT matrix and a phase rotation matrix, but also a first type matrix as a component corresponding to 'A' and 'B' Lt; / RTI > matrix.

Hereinafter, the process of selecting the second matrix (S220) will be described in detail with reference to FIG.

The transmitting end receives the identification information of the first matrix formed of a Discrete Fourier Transform (DFT) matrix and a phase-shift matrix in a first period, and performs pre-coding in which channel performance is optimized through multiplication with the first matrix, And obtaining a second matrix constituting the matrix from the predetermined second matrix set.

The step of feeding back the second matrix identification information uses Equation (9).

In Equation (9), Q _i denotes an i-th matrix in the codebook for the first matrix, V _n denotes an n-th matrix in the second matrix set, and M denotes a predetermined metric according to channel performance. When receiving the transmission the value of said first matrix Q _i at a fixed, V _n value of M (Q _i V _n) value is maximized is to select from the set V of the second matrix determined in advance.

The method of obtaining the precoding matrix through the two steps may be modified such that the value of the second matrix selected from the set of predetermined second matrices is fixed and the equation A precoding matrix may be constructed by selecting a first matrix required in the first matrix codebook obtained in Equation (3).

Alternatively, the precoding matrix may be configured by selecting a matrix value satisfying Equation (9) in the first matrix codebook and the second matrix set that are predetermined in the above manner. On the other hand, the receiving side is a terminal and the transmitting side is a base station. The receiving side may be a base station, and the transmitting side may be a terminal.

Next, a method for transmitting a signal by a transmitting terminal using a multiple-input multiple-output scheme according to another embodiment of the present invention will be described.

First, the transmitting end receives identification information of a first matrix composed of a discrete Fourier transform (DFT) matrix and a phase-shift matrix or a matrix including such a matrix from a receiving end in units of a first period, A receiver for receiving identification information of a second matrix constituting a precoding matrix whose channel performance is optimized through multiplication with the first matrix from the receiving end in units of a period and calculating a precoding matrix by multiplying the first matrix by the second matrix . And precoding the signal using the generated precoding matrix and transmitting the precoded signal to the receiver.

And the first period is different from the second period.

Here, the identification information of the first matrix may be expressed by Equation (3) using a specific first matrix calculated through eigenvalue decomposition of a channel correlation matrix for a received signal at the receiving end, When the phase shift matrix is divided into the DFT matrix and the phase shift matrix as shown in Equation (4), it is received as identification information corresponding to the phase value of the phase shift matrix.

Equation (5) is a case where two single polarization antennas of the transmitting end are installed parallel to the reference plane, and Equation (6) represents a case where four single polarized antennas of the transmitting terminal are vertically arranged with respect to the reference plane It is based on the case where it is installed in parallel. The phase shift matrix P _2x2 of Equation 5 is selected to be similar to the value of the first matrix arranged in the first matrix codebook obtained through the eigenvalue decomposition of the correlation matrix of the channel. In this case, it is possible to select a first matrix that is easier than selecting the first matrix directly from a codebook having infinite candidates for the first matrix, and to prevent an increase in the overhead required in the process And the increase in signal transmission time can be solved.

The identification information of the second matrix represents a specific second matrix within a predetermined second matrix set, and the second matrix identification information is obtained by using Equation (9) so that M (Q _i V _n ) V _n , where Q _i is an i-th matrix in the codebook for the first matrix, V _n is an n-th matrix in the second matrix set, M Represents a predetermined metric according to channel performance.

In the method for transmitting a signal using the multi-antenna scheme, it is preferable that the DFT matrix and the second matrix set are determined in advance between the transmitting end and the receiving end, and the receiving end is a terminal, Or. The receiving side may be a base station, and the transmitting side may be a terminal.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The foregoing description of the preferred embodiments of the present invention has been presented for those skilled in the art to make and use the invention. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as defined by the following claims It can be understood that Accordingly, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

1 is a diagram showing a configuration of a general multi-antenna (MIMO) system.

2 is a diagram schematically illustrating a flow of configuring precoding according to an embodiment of the present invention and transmitting a signal using the precoding.

3 is a flowchart illustrating a process of calculating the first matrix according to an embodiment of the present invention.

4 is a diagram schematically showing a case where a transmitting terminal has a dual polarized antenna according to an embodiment of the present invention.

5 is a diagram illustrating a first matrix for a dual polarization MIMO system in one embodiment in accordance with the present invention.

Claims (15)

A method for receiving a signal by a receiving end using a multiple antenna scheme, Estimating a first matrix using channel information of a received signal and feeding back the identification information of the first matrix to a transmitting end in units of a first period; Obtaining a second matrix constituting a precoding matrix through multiplication with the calculated first matrix from a predetermined second matrix set and feeding the identification information of the second matrix to the transmitter in a second period unit; And Receiving a signal from the transmitting end using the precoding matrix generated through the multiplication of the first matrix and the second matrix, The first matrix includes a first type matrix including a Discrete Fourier Transform (DFT) matrix and a phase-shift matrix, and a second type matrix of a matrix type for a dual polarization antenna having the first type matrix as a component. ≪ / RTI > Wherein the step of feeding back the second matrix identification information comprises:

Using an equation such as the M (Q _i V _n) value is fed back to the identification information of the V _n value is maximized as the identification information of the second matrix, and wherein Q _i is i from the codebook for the first matrix V _n denotes an n-th matrix in the second set of matrices, and M denotes a predetermined metric according to channel performance. The method according to claim 1, Wherein the first period is different from the second period. The method according to claim 1, Wherein the first matrix identification information feedback step comprises: Estimating the first matrix through eigenvalue decomposition of a channel correlation matrix of the received signal; And Dividing the estimated first matrix by the DFT matrix and the phase shift matrix and transmitting identification information corresponding to a phase value of the phase shift matrix as identification information of the first matrix, . The method according to claim 1, Wherein the DFT matrix and the second matrix set are predetermined between the transmitting end and the receiving end. delete The method according to claim 1, Wherein the receiving terminal is a terminal and the transmitting terminal is a base station. The method according to claim 1, Wherein the receiving end is a base station and the transmitting end is a terminal. A method for transmitting a signal using a multi-antenna scheme, the method comprising: Receiving identification information of a first matrix from a receiving end in units of a first period; Receiving identification information of a second matrix constituting a precoding matrix through multiplication with the first matrix from a receiving end in units of a second period; Precoding a signal using the precoding matrix generated through multiplication of the first matrix and the second matrix; And And transmitting the precoded signal to the receiving end, The first matrix includes a first type matrix including a Discrete Fourier Transform (DFT) matrix and a phase-shift matrix, and a second type matrix of a matrix type for a dual polarization antenna having the first type matrix as a component. ≪ / RTI > Wherein the second matrix identification information comprises:

, Q _i is received as identification information of a V _n value that maximizes the value of M (Q _i V _n ), and Q _i is an i-th matrix in the codebook for the first matrix, and V _n Wherein M denotes an n-th matrix in the second set of matrices, and M denotes a predetermined metric according to channel performance. 9. The method of claim 8, Wherein the first period is different from the second period. 9. The method of claim 8, The identification information of the first matrix is divided into a DFT matrix and a phase shift matrix by a specific first matrix calculated through an eigenvalue decomposition of a channel correlation matrix for a reception signal at the receiver. The phase shift matrix is received as identification information corresponding to a phase value of the phase shift matrix. 9. The method of claim 8, Wherein the identification information of the second matrix represents a specific second matrix within a predetermined second matrix set. delete 9. The method of claim 8, Wherein the DFT matrix and the second matrix set are predetermined between the transmitting end and the receiving end. 9. The method of claim 8, Wherein the receiving end is a terminal and the transmitting end is a base station. 9. The method of claim 8, Wherein the receiving end is a base station and the transmitting end is a terminal.

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