KR101322819B1 - Methods of interference alignment for time-varying multiuser mimo interference channels - Google Patents

Abstract

PURPOSE: An interference alignment method for time-varying multiuser MIMO interference channels is provided to sequentially generate beamforming matrices of a terminal by using given dummy beamforming matrices. CONSTITUTION: A second transmission unit receives a first arbitrary dummy beamforming matrix and channel information between a first reception unit and the second transmission unit from the first reception unit and generates a second transmission beamforming matrix (S303). A third transmission unit receives the first arbitrary dummy beamforming matrix and channel information between the first reception unit and the third transmission unit from the first reception unit and generates a third transmission beamforming matrix. A first transmission unit receives a second dummy beamforming matrix and channel information between a second reception unit and the first transmission unit from the second reception unit and generates a first transmission beamforming matrix (307). [Reference numerals] (AA) Start; (BB) End; (S301) First reception unit produces a promised arbitrary dummy beamforming matrix; (S302) Second and third transmission units receive information about a channel from the first reception unit; (S303) Second and third transmission units form a transmission beamforming matrix according to the received information; (S304) Second reception unit receives the channel information from the third transmission unit; (S305) Second reception unit produces a dummy beamforming matrix according to the received information; (S306) First transmission unit receives the channel information from the second reception unit; (S307) First transmission unit produces a transmission beamforming matrix according to the received information; (S308) Each transmission unit normalizes the transmission matrixes; (S309) First and second reception units produce a reception beamforming matrix meeting the dummy matrixes at right angles; (S310) Third reception unit produces a reception beamforming matrix minimizing interference

Description

METHODS OF INTERFERENCE ALIGNMENT FOR TIME-VARYING MULTIUSER MIMO INTERFERENCE CHANNELS}

The present invention relates to interference alignment, and more particularly, to a partial interference alignment method.

An interference channel (IC) is a channel situation in which information is sent from each transmitter to each receiver, and signals from other transmitters in the same space are all interfered with. Interference Alignment (IA) classifies one's spaces into two spaces in an interference channel situation, aligns signals of one's transmitters into one space, and arranges interference signals from another transmitter into one space. Zero Forcing).

Assuming that K transmitters in the same space transmit information to each designated receiver in an interference channel situation, using a method of canceling interference by using the orthogonality of a signal, a user may use 1 of his available channel capacity. Since / K can be used, the channel capacity does not increase with the number of users. However, using the interference alignment method, when multiple users communicate in the same space interference channel, each user can use 1/2 of the available channel capacity. K / 2.

However, interference alignment is a problem that can be realized only when a user in the same space knows global channel knowledge corresponding to spatial information of other users who interfere in the same space.

To solve this problem, Distributed IA has been disclosed. Distributed interference alignment enables interference alignment using only local channel knowledge by using repetitive transmission of channel information between a transmitter and a receiver through channel symmetry and cognitive principles. However, there is a problem that the number of transmission of channel information repeated between a transmitting end and a receiving end is large to perform distributed interference alignment.

Republic of Korea Patent Publication KR 10-2011-0086449 (Subspace interference alignment method, Korea Electronics and Telecommunications Research Institute, published on July 28, 2011)

SUMMARY OF THE INVENTION An object of the present invention is to provide a partial interference alignment method which achieves a transmission gain similar to that of a conventional distributed interference alignment technique while being performed by transmitting a limited number of transmitting and receiving channel information.

The interference alignment method of the present invention for achieving the above object is a interference alignment method in a time-varying multi-user multi-antenna interference channel environment comprising a first, second, third transmitter and first, second, third receiver, the second The transmitting end receiving an arbitrary first dummy beamforming matrix and channel information between the first receiving end and the second transmitting end from the first receiving end to generate a second transmission beamforming matrix; A third transmitting end receiving an arbitrary first dummy beamforming matrix and channel information between the first receiving end and the third transmitting end from the first receiving end to generate a third transmitting beamforming matrix; And a first transmitting end receiving a second dummy beamforming matrix from the second receiving end, wherein the second dummy beamforming matrix receives a transmission beamforming matrix of the third transmitting end and channel information between the third transmitting end and the second receiving end. Generated-and receiving channel information between the second receiver and the first transmitter to generate a first transmit beamforming matrix.

를 이용하여 상기 제 2 송신 빔형성 행렬을 생성하고 - 여기서

는 상기 제 2 송신단의 제 2 빔형성 행렬이고,

는 제 2 송신단에서 제 1 수신단으로의 채널 정보를 나타내는 행렬이며,

은 상기 제 1 수신단의 제 1 더미 빔형성 행렬임-, 상기 제 3 송신단이

를 이용하여 상기 제 3 송신 빔형성 행렬을 생성할 수 있다 - 여기서

는 상기 제 3 송신단의 제 3 빔형성 행렬이고,

는 제 3 송신단에서 제 1 수신단으로의 채널 정보를 나타내는 행렬이며,

은 상기 제 1 수신단의 제 1 더미 빔형성 행렬임-.The second transmitting end and the third transmitting end generating the transmission beamforming matrix may include:

Generate the second transmit beamforming matrix using

Is a second beamforming matrix of the second transmitter,

Is a matrix representing channel information from the second transmitter to the first receiver,

Is a first dummy beamforming matrix of the first receiving end, wherein the third transmitting end is

Can generate the third transmit beamforming matrix using

Is a third beamforming matrix of the third transmitter,

Is a matrix representing channel information from a third transmitting end to a first receiving end,

Is a first dummy beamforming matrix of the first receiving end.

-여기서 상기

는 상기 제 3 송신단의 제 3 빔형성 행렬이고, 상기

는 제 3 송신단에서 제 2 수신단으로의 채널 정보를 나타내는 행렬이며, 상기

은 상기 제 2 수신단의 제 2 더미 빔형성 행렬임-를 이용하여 상기 더미 빔형성 행렬을 생성할 수 있다.The generating of the second dummy beamforming matrix by the second receiving end is performed by the second receiving end.

-Remind me here

Is a third beamforming matrix of the third transmitter,

Is a matrix representing channel information from a third transmitting end to a second receiving end.

May generate the dummy beamforming matrix using the second dummy beamforming matrix of the second receiver.

- 여기서 상기

는 상기 제 1 송신단의 제 1 빔형성 행렬이고, 상기

는 제 1 송신단에서 제 2 수신단으로의 채널 정보를 나타내는 행렬이며, 상기

은 상기 제 2 수신단의 제 2 더미 빔형성 행렬임 -를 이용하여 상기 제 1 송신 빔 형성 행렬을 생성할 수 있다.The first transmitting end generates the first transmission beamforming matrix by the first transmitting end.

Where said

Is a first beamforming matrix of the first transmitter,

Is a matrix representing channel information from a first transmitting end to a second receiving end.

Is a second dummy beamforming matrix of the second receiver, to generate the first transmission beamforming matrix.

The interference alignment method may further include normalizing the transmission beamforming matrix by the first, second, and third transmitters.

을 이용하여 - 여기서 상기

는 상기 제 k 송신단의 빔형성 행렬이고, 상기 k는 1과 3사이의 정수이며, 상기

는 행렬

의 d번째로 작은 고유값에 대한 고유벡터를 의미함 - 수행될 수 있다.The normalization step is

Using-where the above

Is a beamforming matrix of the k-th transmitter, k is an integer between 1 and 3,

The matrix

Means the eigenvector for the d-th smallest eigenvalue of-can be performed

The interference alignment method may further include generating, by the first and second receivers, a reception beamforming matrix orthogonal to the dummy beamforming matrix.

을 이용하여 - 여기서 상기

는 상기 제 k 수신단의 수신 빔형성 행렬이고, 상기 k는 1 또는 2 임- 수행될 수 있다.Generating the receive beamforming matrix

Using-where the above

Is the reception beamforming matrix of the k-th receiving end, and k may be 1 or 2.

The interference alignment method may further include generating, by the third receiving end, a reception beamforming matrix for minimizing interference.

을 이용하여 - 여기서 상기

는 행렬

의 d번째로 작은 고유값에 대한 고유벡터를 의미하고, 상기

는 제 3 수신단의 채널 정보를 특이값 분해(Singular Value Decomposition; SVD) 또는 고유값 분해 (Eigen Value Decomposition; EVD)한 값임 - 생성될 수 있다.The third receive beamforming matrix of the third receiver is

Using-where the above

The matrix

Means the eigenvector for the d-th smallest eigenvalue of

Is a value obtained by singular value decomposition (SVD) or eigen value decomposition (EVD) of channel information of the third receiver.

The interference alignment method may be performed in an interference channel situation in which there is no base station.

In addition, the partial interference alignment method of the present invention for achieving the above object, the interference alignment method in a time-varying multi-user multi-antenna interference channel environment, comprising: subdividing the N transmission and reception pairs into a sub transmission and reception set; And performing the interference sorting of any one of claims 1 and 11 with respect to the partial sub transmission / reception set.

The sub transmission / reception set may include a maximum of three pairs of transmission / reception sets.

According to the partial interference alignment method according to the above-described embodiment of the present invention, the beamforming matrix of the UE is sequentially generated using a predetermined random beamforming matrix, thereby performing repeated transmission of channel information for performing interference alignment. By reducing the overhead, a limited number of transmissions of channel information can achieve a conventional distributed interference alignment or a sum rate similar to that of a single user MIMO.

1 is a conceptual diagram of a K-user multiple input multiple output (MIMO) system in an interference channel without a base station.
2 is a flow chart illustrating performance of a conventional distributed interference alignment.
3 is a flowchart illustrating an order in which a partial interference alignment method according to an embodiment of the present invention is performed in a situation where three users communicate in an interference channel.
4 is a chart comparing the sum rate performance according to the partial interference alignment method and the conventional alignment method according to an embodiment of the present invention.
5 is a diagram illustrating the number of repetitive transmission times according to the signal-to-noise ratio (SNR) in the partial interference alignment method and the conventional method according to an embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail.

It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

When a component is referred to as being "connected" or "connected" to another component, it may be directly connected to or connected to that other component, but it may be understood that other components may be present in between. Should be. On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the relevant art and are to be interpreted in an ideal or overly formal sense unless explicitly defined in the present application Do not.

1 is a conceptual diagram of k user multiple input multiple output (MIMO) systems in an interference channel without a base station. Each transmitting end 111, 112, 113 and each receiving end 121, 122, 123 are shown.

Since there is no base station, each transmitting end (111, 112, 113) and the receiving end (121, 122, 123) can only know the channel information of the region received by them. The transmitting end and receiving end of the k-th user have M ^[k] and N ^[k] antennas, respectively, and each transmitting end (111, 112, 113) transmits d ^[k] data streams to the designated receiving end (121, 122, 123). do. The k-th user includes a k-th transmitter and a k-th receiver. Transmitters and receivers belonging to one user alternately transmit and receive data, and signals belonging to different users act as interference signals to other users.

번째 송신단에서의 파워는

로 계산되며, 송신단 안에서 각각의 데이터 스트림은

의 파워를 가진다. 여기서,

는 간섭 대 신호 비 (Interference to Signal Ratio; SIR)를 의미한다. In Equation 1, Y ^[k] is a received signal of the k-th receiving end represented by the N ^[k] x 1 matrix. X ^[l] is a transmission signal of the l & lt ^{; th} > Here, X ^[l] = V ^[l] xd ^[l] , and V ^[k] is a transmission beamforming matrix represented by the M ^[l] xd ^[l] matrix. Z ^[k] is a complex white Gaussian noise with a mean of 0 and a variance of 1 and is represented by an N ^[k] x 1 matrix. The rail-rail fading channel H ^[kl] represents a channel from the transmitting end to the receiving end, and is represented by an N ^[k] x M ^[l] matrix.

Power at the first transmit end

In the transmitter, each data stream

Has the power of. here,

Denotes an interference to signal ratio (SIR).

After transmitting information from the transmitting end (111, 112, 113) to the receiving end (121, 122, 123), the former receiving end (121, 122, 123) is replaced by the previous receiving end (111, 112, 113) by changing the role of the transmitting and receiving end To send information. The channel of the k-th receiver in the reverse direction is defined as in Equation 2. An example applied to the Min Leakage algorithm is described below.

2 is a flow chart illustrating performance of a conventional distributed interference alignment. In the conventional distributed interference alignment technique, the transmitter transmits channel information, the receiver receives channel information, generates a beamforming matrix, calculates the power of the interference signal, and performs the interference alignment, but the power of the interference signal converges as a result. In this case, a method of transmitting channel information between the transmitting and receiving end and completing the interference alignment is used.

In the conventional distributed interference alignment method, each of the transmitters 111, 112, and 113 generates an arbitrary transmission beamforming matrix (S201) and transmits channel information. Next, each receiving end 121, 122, 123 receives local channel information from each transmitting end (S202). In addition, interference between signals is eliminated by generating an interference suppression matrix that minimizes interference at each receiving end 121, 122, and 123 (S203). The received signal of the k-th receiver, which computed the interference suppression matrix, is defined as in Equation 3. The interference suppression matrix of each of the receivers 121, 122, and 123 may be generated by using Equations 4 and 5 below.

는 행렬

의 d번째로 작은 고유값에 대한 고유벡터를 의미한다. 이후 수신단은 수학식 6과 같이 간섭 억제 행렬을 송신 빔형성 행렬로 사용하여 채널 정보를 전송한다(S204). here

The matrix

Eigenvectors for the d-th smallest eigenvalue of. Thereafter, the receiving end transmits channel information using the interference suppression matrix as a transmission beamforming matrix as shown in Equation 6 (S204).

Each transmitter 111, 112, and 113 receives channel information from each receiver 121, 122, and 123 (S205), and generates a transmission beamforming matrix using the received channel information as described above ( S206).

Next, each of the transmitters 111, 112, and 113 measures the power of the interference signal by using Equation 7.

Each transmitter 111, 112, 113 stops repetitive transmission of channel information when it is determined that the interference power has converged as a result of measuring the power of the interference signal. That is, in the conventional distributed interference alignment, the interference signal is aligned by repeatedly transmitting channel information of the transmitting and receiving end until the power of the interference signal is converged.

On the contrary, if it is determined that the power of the interference signal is not converged, each transmitter 111, 112, 113 transmits channel information back to each receiver 121, 122, 123 (S207). Here, each of the receivers 121, 122, and 123 may regenerate the reception beamforming matrix, determine whether the interference signal converges, and determine whether to transmit channel information to each of the transmitters 111, 112, and 113 again. .

The distributed interference sorting method through the transmission of repeating channel information is easily applicable to various numbers of users and can achieve high sum-rate, but it is required to repeat transmission of channel information of a high number of times.

 In addition, the conventional distributed interference alignment is limited in the number of users that the technique can be implemented depending on the number of antennas of the transmitting and receiving end. If all transmitters 111, 112, 113 and receivers 121, 122, 123 have the same number of antennas, M and N, respectively, and all transmitters 111, 112, 113 assume a symmetric system for transmitting d data, the prior art Execution is possible only when the condition as in Equation 8 is satisfied.

3 is a flowchart illustrating an order in which a partial interference alignment method according to an embodiment of the present invention is performed in a situation where three users communicate in an interference channel. Hereinafter, the partial interference alignment method according to an embodiment of the present invention and the transmitting end (111, 112, 113) having the number of antennas (M = N = 2 xd) of twice the degree of freedom (DoF) and A description will be given in a situation where three pairs of transmitting and receiving terminals (users) composed of the receiving terminals 121, 122, and 123 communicate.

를 생성한다(S301).

는 각 수신단(121, 122, 123)에 기 설정되어 있는 값으로, 각 수신단(121, 122, 123) 모두가 같은 값으로 가지고 있을 수 있다. 여기서 더미 빔행렬

는

인 임의의 행렬이다.First, the receiver 1 has an arbitrary dummy beam matrix.

To generate (S301).

Is a value that is set in advance in each of the receivers 121, 122, and 123, and all of the receivers 121, 122, and 123 may have the same value. Where dummy beam matrix

The

Is an arbitrary matrix

및 채널정보를 전송한다. 2, 3번째 송신단은 수신단 1의 임의의 더미 빔행렬

및 수신단 1과 자신간의 채널 정보를 수신하고(S302), 수신 정보에 따라 송신 빔형성 행렬

,

을 생성한다(S303). 여기서, 송신단 2의 송신 빔형성 행렬

는 수학식 10를 이용하여 생성될 수 있고, 송신단 3의 송신 빔형성 행렬

은 수학식 11을 이용하여 생성될 수 있다. 그리고 송신단 3은 송신 빔형성 행렬

및 채널 정보를 송신한다.Next, the receiver 1 receives an arbitrary dummy beam matrix.

And channel information. 2nd and 3rd transmitters are random dummy beam matrix of receiver 1

And receiving channel information between the receiver 1 and itself (S302) and transmitting beamforming matrix according to the received information.

,

To generate (S303). Here, the transmission beamforming matrix of the transmitter 2

Can be generated using Equation 10, and the transmit beamforming matrix of the transmit end 3

May be generated using Equation 11. And the transmit end 3 is a transmit beamforming matrix.

And channel information.

및 송신단 3과 수신단 2 사이의 채널 정보를 수신받는다(S304). 그리고 더미 빔행렬

를 생성한다(S305).

는 수학식 12를 사용하여 생성될 수 있다. Next, the receiving end 2 is a transmit beamforming matrix of the transmitting end 3

And channel information between the transmitter 3 and the receiver 2 (S304). And dummy beam matrix

To generate (S305).

May be generated using Equation 12.

및 채널 정보를 전송하면, 송신단 1이 빔행렬

및 수신단 2와 송신단 1 사이의 채널 정보를 수신받는다(S306). 송신단 1은 전술한 바와 같이 첫 번째 송신단의 송신 빔형성 행렬을 생성한다(S307). 여기서, 송신단 1은 수학식 13을 이용하여 송신 빔형성 행렬을 생성할 수 있다.Next, the receiving end 2 is a dummy beam matrix

And transmitting the channel information, the transmitting end 1 beam matrix

And channel information between the receiver 2 and the transmitter 1 (S306). As described above, the transmitter 1 generates a transmission beamforming matrix of the first transmitter (S307). Here, the transmitter 1 may generate a transmission beamforming matrix using Equation 13.

Next, each transmitting end 111, 112, and 113 normalizes the transmission beamforming matrix (S308). Each transmitter 111, 112, and 113 may normalize the size of each transmission beamforming matrix using Equation 14.

에 직교하고 정규화된 수신 빔형성 행렬을 생성할 수 있다.Next, the receivers 1 and 2 generate a reception beamforming matrix orthogonal to the dummy beam matrix using the dummy beam matrix (S309). Each receiving end (121, 122, 123) using the equation (15)

An orthogonal and normalized receive beamforming matrix may be generated.

Finally, the receiver 3 generates a reception beamforming matrix to minimize interference (S310). The receiver 3 may generate a reception beamforming matrix using Equation 16.

이고 3명의 유저가 M=N=2, d=1 인 환경에서 측정된 모의 실험 결과이다.4 is a chart comparing the sum-rate performance of the partial interference alignment method and the conventional method according to an embodiment of the present invention. 4 is the interference to signal ratio

And three users, M = N = 2, d = 1.

In the case of using the conventional distributed interference alignment method using the sufficient number of repeated transmission of channel information (DIA), in the case of using the conventional distributed interference alignment method by limiting the number of repetitive transmission of the channel information to two times (DIA-2iteration), a single user M The sum rate according to the signal-to-noise ratio is shown in the case of = N = 2, d = 2 and in the case of using the partial interference alignment method (PIA) according to an embodiment of the present invention.

은

송신단에서

수신단으로의 채널의 파워이다. 합전송률은 수학식 18로 측정되었으며, 충분한 채널 정보 반복 전송 횟수를 사용한 종래의 간섭 정렬 방법을 사용한 경우(DIA) 반복 전송후의 간섭 전력의 차가 0.001 이하가 되면 간섭 전력이 수렴되었다고 판단하여 반복 전송을 중지하고 합전송률을 구하였다.here

silver

At the sending end

The power of the channel to the receiver. The sum rate was measured by Equation 18. When the conventional interference alignment method using sufficient number of repeated repetitive transmissions of channel information is used (DIA), when the difference in the interference power after repeated transmission becomes 0.001 or less, it is determined that the interference power has converged. Stop and get the sum rate.

As shown in FIG. 4, the partial interference alignment method according to an embodiment of the present invention has a lower sum rate than the conventional distributed interference alignment method having a sufficient number of repetitive transmissions of channel information, but has a limited number of interferences ( For example, when the number of repeated channel transmissions is 2), it can be confirmed that the highest sum rate can be achieved.

5 is a diagram illustrating the performance of the number of repetitive transmissions according to the signal-to-noise ratio (SNR) of the partial interference alignment method and the conventional method according to an embodiment of the present invention. 5 shows a result of comparing actual transmission times according to each alignment method. As shown in FIG. 5, the conventional distributed interference alignment technique requires more repetitive channel transmissions as the SNR increases, whereas the proposed scheme requires a constant number of repetitive transmissions of 2 regardless of the SNR.

As described above, the partial interference alignment method according to an embodiment of the present invention generates the reception beamforming matrix promised to one terminal and sequentially generates the beamforming matrix of the terminal. Although there is a disadvantage in that not all interference can be eliminated, it is possible to reduce the repetitive transmission overhead of channel information for executing the distributed interference matrix to a practical value.

In addition, the partial interference alignment method according to another embodiment of the present invention may be applied to a case having a different number of users or other situations according to the illustrated method. For example, when the number of users increases, all users except one user can arrange interference with two other users. Therefore, in the present invention, when the number of antennas is fixed and the number of users increases, the receiving end allows some interference but can perform the interference alignment for the partial users.

In addition, the partial interference sorting method according to another embodiment of the present invention may be performed by subdividing the entire set of users into a subset consisting of three users. The present invention may solve the overhead of repetitive transmission of channel information required for conventional distributed interference alignment by performing partial interference alignment for a subset of users.

Claims (13)

In the interference alignment method in a time varying multi-user multi-antenna interference channel environment comprising a first, second, third transmitter and first, second, third receiver,
Generating, by the second transmitting end, an arbitrary first dummy beamforming matrix from the first receiving end and channel information between the first receiving end and the second transmitting end to generate a second transmission beamforming matrix;
Generating, by the third transmitting end, an arbitrary first dummy beamforming matrix from the first receiving end and channel information between the first receiving end and the third transmitting end to generate a third transmitting beamforming matrix; And
Wherein the first transmitting end is configured to receive a second dummy beamforming matrix from the second receiving end, wherein the second dummy beamforming matrix is a transmission beamforming matrix of the third transmitting end and channel information between the third transmitting end and the second receiving end. Receiving and generating channel information between the second receiving end and the first transmitting end to generate a first transmit beamforming matrix.
The method of claim 1, wherein the second transmitter and the third transmitter generate the transmission beamforming matrix.
The second transmitting end

Generate the second transmit beamforming matrix using

Is a second beamforming matrix of the second transmitter,

Is a matrix representing channel information from the second transmitter to the first receiver,

Is a first dummy beamforming matrix of the first receiving end,
The third transmitting end

Generate the third transmit beamforming matrix using

Is a third beamforming matrix of the third transmitter,

Is a matrix representing channel information from the third transmitter to the first receiver,

Is a first dummy beamforming matrix of the first receiving end. 3. The method of claim 2, wherein the generating of the second dummy beamforming matrix by the second receiving end comprises:

Where said

Is a third beamforming matrix of the third transmitter,

Is a matrix representing channel information from the third transmitter to the second receiver,

Generates the dummy beamforming matrix using the second dummy beamforming matrix of the second receiver. 4. The method of claim 3, wherein the generating of the first transmit beamforming matrix by the first transmitting end comprises:

Where said

Is a first beamforming matrix of the first transmitter,

Is a matrix representing channel information from the first transmitting end to the second receiving end.

Is the second dummy beamforming matrix of the second receiving end to generate the first transmit beamforming matrix. 5. The method of claim 4, wherein the interference alignment method further comprises the step of: the first, second, and third transmitters normalizing the transmission beamforming matrix. 6. The method of claim 5 wherein the normalization step is

Using-where the above

Is a beamforming matrix of the k-th transmitter, k is an integer between 1 and 3,

The matrix

Means the eigenvector for the d-th smallest eigenvalue of-the interference alignment method. 7. The method of claim 6, wherein the interference alignment method further comprises the step of generating, by the first and second receivers, a reception beamforming matrix orthogonal to the dummy beamforming matrix. 8. The method of claim 7, wherein generating the receive beamforming matrix

Using-where the above

Is a reception beamforming matrix of the k-th receiving end, and k is 1 or 2. 10. The method of claim 8, wherein the interference alignment method further comprises the step of generating, by the third receiving end, a reception beamforming matrix that minimizes interference. The method of claim 9, wherein the third receiving beamforming matrix of the third receiving end is

Using-where the above

Is the matrix

Means the eigenvector for the d-th smallest eigenvalue of

Is a value obtained by singular value decomposition (SVD) or eigen value decomposition (EVD) of channel information of the third receiver. 11. The method of claim 10,
And the interference alignment method is performed in an interference channel situation in which there is no base station. An interference alignment method in a time varying multi-user multi-antenna interference channel environment,
Subdividing the N transmit / receive pairs into a sub transmit / receive set; And
12. The method of claim 1, further comprising performing the interference sorting of any one of claims 1 and 11 on the partial sub-transmitted and received sets. 13. The method of claim 12,
And the sub transmission / reception set includes a maximum of three pairs of transmission / reception sets.

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