KR101204237B1 - Base station, MoBILE Communication TERMINAL and Method for GENERATING BEAM FORMING MATRINX IN the base station - Google Patents

Abstract

A method of generating a beamforming matrix of a base station, a terminal, and a base station is disclosed. The disclosed base station is a base station having n transmit antennas, wherein n is two or more natural numbers, and transmits a first signal formed using a non-orthogonal beamforming matrix to a plurality of terminals through the plurality of transmit antennas. A transmitting unit for transmitting; A receiving unit receiving a second signal including feedback information on the first signal from at least one terminal;
A terminal selector which selects at least one terminal to communicate using the second signal; And a matrix generator for generating a beamforming matrix for data transmission to the selected at least one terminal by using the second signal. According to the present invention, even if the number of terminals communicating with the base station in the MIMO communication system can generate a beamforming matrix that can maximize the transmission capacity.

Description

Base station, MoBILE Communication TERMINAL and Method for GENERATING BEAM FORMING MATRINX IN the base station}

One embodiment of the present invention relates to a method for generating a beamforming matrix of a base station, a terminal, and a base station. More particularly, the method for generating a beamforming matrix of a base station and a base station selects a terminal from the base station and generates beamforming metrics for the selected terminal. It is about.

A so-called MIMO wireless communication system that transmits and receives data between a base station and a terminal using a plurality of transmit antennas and a plurality of receive antennas can increase data transmission throughput in a multi-user environment through simultaneous transmission of a plurality of user data. have.

는 기지국과 단말기간의 무선통신 채널(이하, ‘MIMO 채널’이라 함)에 의해 다음의 수학식1 같은 형태로 단말기에 전달된다.Symbol vector transmitted from the base station in the MIMO wireless communication system used in the multi-antenna system for mobile broadcasting

Is transmitted to the terminal in the form of the following Equation 1 by a wireless communication channel (hereinafter referred to as 'MIMO channel') between the base station and the terminal.

[ Equation 1 ]

는

차원의 송신벡터,

는 단말기 k와 기지국 사이의 MIMO 채널 메트릭스로서, 송신 안테나의 수가

, 수신 안테나의 수가

인 경우

의 크기를 갖는다. 그리고

는

차원의 노이즈 벡터이다.here,

The

Dimensional Transmission Vector,

Is the MIMO channel metric between terminal k and the base station, where the number of transmit antennas

, The number of receiving antennas

If

Has the size of. And

The

Dimensional noise vector.

는 특이값 분해(SVD: singular value decomposition)에 의해

의 세 개의 메트릭스의 조합으로 나타내어질 수 있다.

와

는 각각

,

차원의 유니터리(unitary) 메트릭스이며,

는

차원의

의 특이값을 가지는 대각 메트릭스이다.Where channel metrics

Is determined by singular value decomposition (SVD).

It can be expressed as a combination of three metrics of.

Wow

Respectively

,

Unitary metrics for dimensions,

The

Dimension

Diagonal matrix with the singular value of.

에 관한 정보를 갖고 있는 경우, 기지국은 송신벡터

에

의 에르미트 공액(Hermitian conjugate)인

를 곱하여 전송하고, 단말기에서는 수신된 벡터

에

의 에르미트 공액인

를 곱함으로써, 송신 벡터

가 다음의 수학식2와 같이 페러렐 가우시안 채널을 통해 전송된 것과 같은 효과를 거둘 수 있다.Channel metrics at base station

If it has information about the base station,

on

Hermitian conjugate of

Multiply by and transmit the received vector

on

Hermit conjugate

By multiplying by

As shown in Equation 2 below, the same effects as those transmitted through the parallel Gaussian channel can be obtained.

& Quot; (2 ) & quot ;

는 페러렐(parallel) 가우시안 채널의 잡음 신호를 나타낸다.here,

Denotes a noise signal of a parallel Gaussian channel.

는 고유채널(Eigen channel)이라고 불리는

의

개의 대각 성분을 채널 메트릭스

의 특이값으로서 갖는다. 기지국은

을 이용하여 워터필링(water-filling) 기법에 의해 송신 벡터

의 송신전력을 결정할 수 있으며, 이것은 MIMO 채널에서 송신 전력을 결정하는 최적 기법으로 알려져 있다.Diagonal metrics

Is called the Eigen channel

of

Diagonal components with channel metrics

It has as a singular value of. The base station

Transmission vector by water-filling technique using

It is possible to determine the transmit power of the signal, which is known as the optimal technique for determining the transmit power in the MIMO channel.

에 관한 완전한 정보(full information)를 보유할 필요가 있다. 따라서 이 경우, 단말기에서 상당량의 채널 상태 정보(CSI: channel state information)를 기지국으로 피드백 전송하는 오버헤드가 발생한다. 이러한 피드백 오버헤드를 줄이기 위해 랜덤 빔형성(beam forming) 기법이 적용될 수 있다.However, the channel matrix at the base station is

You need to have full information about. Therefore, in this case, an overhead of feedback transmission of a considerable amount of channel state information (CSI) to the base station occurs in the terminal. In order to reduce such feedback overhead, a random beamforming technique may be applied.

1 is a diagram illustrating an example of a communication system to which a conventional random beamforming technique is applied.

개의 송신 안테나(105)를 구비하고 있다. 기지국(100)의 랜덤 빔형성 생성기(103)는 앞서 설명한

에 해당하는 유니터리 메트릭스인

를 랜덤 하게 생성한다.

블록(101)은 랜덤 빔형성 생성기(103)에서 랜덤 하게 생성된

를 심벌 벡터

및 파워 메트릭스

에 곱하여 송신 안테나(105)를 통해 k 번째 단말기(110)로 전송한다. 1 shows the configuration of the base station 100 and the k-th terminal 110, respectively, the base station 100

Two transmission antennas 105 are provided. The random beamforming generator 103 of the base station 100 is described above.

Is the unitary metric

Generates randomly.

Block 101 is randomly generated in the random beamforming generator 103

Symbol vector

And power metrics

Multiply by and transmit to the k-th terminal 110 through the transmit antenna 105.

개의 수신 안테나(111)를 통해 벡터

를 수신한다. 벡터

는 다음의 수학식 3과 같이 표현할 수 있다.k-th terminal 110

Via two receive antennas 111

Receive vector

Can be expressed as Equation 3 below.

& Quot; (3 ) & quot ;

,

는

차원의 직교 빔형성 메트릭스이며,

는

차원의 파워 메트릭스 이다.

s는

차원의 심볼 벡터를 각각 의미한다. here,

,

The

Orthogonal beamforming matrix of dimensions,

The

Dimensional power metrics.

s

Each of the dimension symbols means a vector.

를 추정하며, 이로부터 특이값 분해에 의해 유니터리 메트릭스

를 추출하고, 이를

블록 (113)으로 전달한다.

블록 (113)은 수신된 벡터

에

의 에르미트 공액인

를 곱하여 벡터

를 얻는다.The channel estimation of the k-th terminal 110 and the SVD block 115 is a channel matrix

Is estimated from this unity matrix by singular value decomposition.

And extract it

Pass to block 113.

Block 113 is the received vector

on

Hermit conjugate

Multiply by vector

Get

이고 각 빔형성 벡터에 동일한 파워가 할당되었다고 가정하면

에 대한 복조신호는 다음의 수학식4와 같이 표현될 수 있다.At this time,

Assuming that the same power is assigned to each beamforming vector

The demodulated signal for may be expressed as Equation 4 below.

[ Equation 4 ]

는

의 q번째 특이값이다.

라면

에 대한 SINR 측정블록(117)에서 추정된 SINR은 다음의 수학식5와 같이 표현할 수 있다.here,

The

The qth singular value of.

Ramen

The SINR estimated in the SINR measurement block 117 may be expressed as Equation 5 below.

[ Equation 5 ]

은 노이즈 분산 값이다. here,

Is the noise variance value.

와 비슷한

를 가진다. 하지만, 단말기의 수가 적을 경우에는

와 비슷한

를 가지는 단말기를 찾기가 어렵다.In the conventional random beamforming technique, the base station 100 selects a terminal having a maximum SINR value and performs data communication. Therefore, when there are many terminals communicating with the base station 200 in the MIMO system, the terminal selected by the base station 100 is

Similar to

. However, if the number of terminals is small

Similar to

It is difficult to find a terminal having.

Therefore, in the conventional random beamforming technique using the orthogonal beamforming matrix, when there are many terminals communicating with the base station 100 in the MIMO system, the communication performance is good, but when the number of terminals is small, the multi-terminal gain is not sufficiently obtained. This happens.

와 닮은 채널 특성을 가지는 단말기를 찾지 못함으로써 많은 성능 감소를 가지는 문제점이 발생한다.That is, orthogonal beamforming matrix

There is a problem that there is a lot of performance reduction by not finding a terminal with channel characteristics similar to.

In order to solve the problems of the prior art as described above, the present invention is to provide a method for generating a beamforming matrix of a base station, a terminal and a base station for good communication performance even when the number of terminals communicating with the base station in the MIMO communication system is small. .

Other objects of the present invention may be derived by those skilled in the art through the following examples.

According to a preferred embodiment of the present invention to achieve the above object, n-n is a base station having a transmission antenna of two or more natural numbers, a base formed by using a non-orthogonal beam forming matrix A transmitter for transmitting one signal to a plurality of terminals through the plurality of transmit antennas; A receiving unit receiving a second signal including feedback information on the first signal from at least one terminal; A terminal selector which selects at least one terminal to communicate using the second signal; And a matrix generator for generating a beamforming matrix for data transmission to the selected one or more terminals using the second signal.

Here, the feedback information may include a phase difference code between the n signal-to-noise ratios (SINR) and the n signal-to-noise ratios estimated using the first signal in each of the one or more terminals.

The receiver may receive the second signal from a terminal having an estimated transmission capacity estimated using the n signal-to-noise ratios of the at least one terminal having a value larger than a preset transmission capacity threshold.

The terminal selector may select the first terminal that transmits the largest signal-to-noise ratio (SINR) among the terminals that transmit the second signal.

Here, the matrix generator may generate the orthogonal beamforming matrix for the first terminal using the magnitude, phase, and phase difference code extracted from the n signal-to-noise ratios.

The terminal selector may further select a second terminal having an orthogonality with the selected first terminal greater than or equal to a preset orthogonal threshold among the terminals transmitting the second signal.

Herein, when the second terminal is additionally selected in addition to the first terminal, the matrix generator generates a beamforming matrix for communication with the first terminal and the second terminal, and reduces interference between a plurality of selected terminals. The beamforming matrix may be generated by using a zero-forcing beam forming method.

According to another embodiment of the present invention, there is provided a terminal comprising: a terminal receiver configured to receive a first signal formed using a non-orthogonal beamforming matrix from a base station having n transmit antennas, wherein n is a natural mission of two or more; A feedback information generator configured to generate feedback information on the first signal; And a terminal transmitter for transmitting the feedback information to the base station, wherein the feedback information includes n signal-to-noise ratios (SINRs) estimated using the non-orthogonal beamforming matrix and a phase difference code between the n signal-to-noise ratios. A terminal is provided, which is characterized by the above-mentioned.

Further, according to another embodiment of the present invention, in a method of generating a beamforming matrix of a base station having n-n being two or more natural numbers transmission antennas, the first signal formed by using a non-orthogonal beamforming matrix is described. Transmitting to a plurality of terminals via a plurality of transmit antennas; Receiving from the at least one terminal a second signal comprising feedback information for the first signal; Selecting at least one terminal to communicate using the second signal; And generating a beamforming matrix for data transmission to the selected one or more terminals by using the second signal.

According to the present invention, even if the number of terminals communicating with the base station in the MIMO communication system can generate a beamforming matrix that can maximize the transmission capacity.

1 is a diagram illustrating an example of a communication system to which a conventional random beamforming technique is applied.
2 is a block diagram showing a detailed configuration of a base station according to an embodiment of the present invention.
3 is a flowchart illustrating the overall flow of a method for generating a beamforming matrix of a base station according to an embodiment of the present invention.
4 is a diagram illustrating an example of a communication system according to an embodiment of the present invention.
FIG. 5 is a graph illustrating average transmission capacity according to SNR values when two transmitting and receiving antennas are serviced and a single terminal is serviced according to an embodiment of the present invention.
FIG. 6 is a graph illustrating an average transmission capacity according to an SNR value when a transmitting / receiving antenna is serviced to a single terminal when two or four antennas according to an embodiment of the present invention.
7 is a graph illustrating an average transmission capacity according to the number of terminals when two transmitting and receiving antennas according to an embodiment of the present invention.
8 is a graph illustrating an average transmission capacity according to the number of terminals when four transmitting and receiving antennas according to an embodiment of the present invention.
9 is a graph showing an average SINR feedback number according to the number of terminals according to an embodiment of the present invention.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to or limited by the embodiments. Like reference symbols in the drawings denote like elements.

2 is a block diagram showing a detailed configuration of a base station according to an embodiment of the present invention.

2, the base station 200 according to an embodiment of the present invention may include a transmitter 201, a receiver 203, a terminal selector 205, and a matrix generator 207.

The transmitter 201 transmits the first signal formed by using the non-orthogonal beamforming matrix to the plurality of terminals through n transmit antennas, where n is a natural number of two or more, in order to receive SINR feedback information from each terminal.

The receiver 203 receives a second signal including feedback information about the first signal from at least one terminal.

Here, the feedback information may include n signal-to-noise ratios (hereinafter referred to as SINRs) and / or phase difference codes between the n signal-to-noise ratios estimated using non-orthogonal beamforming metrics in each of the at least one terminal. have.

According to an embodiment of the present invention, the receiving unit 203 has an estimated transmission capacity estimated using n signal-to-noise ratios of at least one or more terminals communicating with the base station 200 has a value larger than a preset transmission capacity threshold. The second signal may be received from the terminal.

The terminal selector 205 selects the first terminal that transmits the largest signal-to-noise ratio among the terminals that transmit the second signal.

Subsequently, the matrix generator 207 forms an orthogonal beamforming matrix for the selected terminal using magnitude, phase, and phase difference codes extracted from the n signal-to-noise ratios.

According to an embodiment of the present invention, the terminal selector 205 may include a second orthogonality with the selected orthogonal threshold value greater than or equal to a preset orthogonal threshold among the terminals transmitting the second signal from the base station 200. You can choose more terminals.

In this case, the matrix generator 207 generates a beamforming matrix for communication with the first terminal and the second terminal in the base station 200, and zero-forcing beamforming to reduce interference between the plurality of selected terminals. The beamforming matrix may be generated by using a beam forming method.

The process of generating the beamforming matrix in the base station 200 will be described in more detail through the following equation.

,

는

로서 다음의 수학식 6과 같이 표현할 수 있다.Suppose that the base station 200 has two transmit antennas and the k-th terminal has been selected by the terminal selection unit 205.

,

The

As shown in Equation 6 below.

[ Equation 6 ]

이고,

는

의 매그니튜드(magnitude) 값이고

는 위상(phase) 값이다.here,

ego,

The

Is the magnitude value of

Is the phase value.

를 이용하여 형성된 제1 신호를 전송하고 이에 대한 피드백 정보를 받는다고 가정하는 경우 피드백 정보에 포함된 SINR 값은 다음의 수학식 7과 같이 표현할 수 있다.
In general, the effect of the noise value is smaller than the effect on the interference. Therefore, the orthogonal beamforming matrix by the conventional random beamforming technique

If it is assumed that the first signal formed by using and receive feedback information for this SINR value included in the feedback information can be expressed as in the following equation (7).

[ Equation 7 ]

Here, in the conventional random beamforming method of transmitting a signal using an orthogonal beamforming matrix, only a magnitude value of a can be extracted from SINR.

According to an embodiment of the present invention, after the transmitter 201 transmits the first signal using the non-orthogonal beamforming matrix, the receiver 203 receives the second signal including feedback information about the first signal. Receive from

라는 비직교 빔형성 메트릭스를 이용하여 형성된 제1 신호를 전송하면, 제1 신호에 대한 피드백 정보인 SINR은 다음의 수학식8과 같이 나타낼 수 있다.

When the first signal formed using the non-orthogonal beamforming matrix is transmitted, SINR, which is feedback information about the first signal, may be expressed as Equation 8 below.

[ Equation 8 ]

As such, the SINR, which is feedback information on the first signal formed using the non-orthogonal beamforming matrix, includes information on a complex exponential value, unlike the SINR of the orthogonal beamforming matrix. Accordingly, the phase value and the magnitude value may be estimated using two SINR values as shown in Equation 9 below.

[ Equation 9 ]

값을 이용하여, 최종적으로 메트릭스 생성부(207)에서 k번째 단말기에 대한 직교 빔형성 메트릭스를 생성할 수 있다.The value of a

Using the value, the matrix generator 207 may finally generate an orthogonal beamforming matrix for the k-th terminal.

는 다음의 수학식10과 같이 생성될 수 있다.
Where orthogonal beamforming matrix

May be generated as in Equation 10 below.

[ Equation 10 ]

조건을 만족하게 된다. 하지만

이기 때문에

가

로 되지 않을 수 있다. 다시 말하면,

과

가 원래는 뒤바뀐 경우로

가 다음의 수학식 11과 같이 표현될 수 있기 때문이다.Therefore, if an orthogonal beamforming matrix is generated as in Equation 10,

The condition is satisfied. However

Because

end

May not be. In other words,

and

If is originally reversed

Is because Equation 11 can be expressed as

[ Equation 11 ]

를 찾기 위해서, 각 단말기에서 수신되는 피드백 정보는

의 위상 차 부호 값을 추가로 포함할 수 있으며, 1bit의 추가적인 bit를 필요로 하게 된다.So properly

In order to find the feedback information received from each terminal

A phase difference code value of may be additionally included, and an additional bit of 1 bit is required.

In this case, the second signal including the feedback information received from the terminal may be expressed by Equation 12 below.

[Equation 12]

Next, a process of generating an orthogonal beamforming matrix when the base station 200 includes two or more transmitting antennas will be described.

는 다음의 수학식13과 같이 나타낼 수 있다.Orthogonal Beamforming Matrix Assuming Two or More Transmitting Antennas

Can be expressed as Equation 13 below.

[ Equation 13 ]

이고,

이다. 높은 SINR을 가정한다면 SINR을 다음의 수식 14와 같이 나타낼 수 있다.The condition for maintaining orthogonality is

ego,

to be. Assuming a high SINR, SINR can be expressed as Equation 14 below.

[ Equation 14 ]

Thus, as in the case of two transmit antennas, the SINR reflects only the magnitude value. As in the case of the two transmit antennas, a non-orthogonal beamforming matrix is constructed. If is a 2D vector, the non-orthogonal beamforming matrix can be expressed by the following equation (15).

[ Equation 15 ]

는 하기의 수학식 16과 같이

개의 채널 메트릭스로 나눌 수 있다.Where channel metrics

Is as shown in Equation 16 below.

It can be divided into channel metrics.

[ Equation 16 ]

Where is the subchannel matrix of. Is the right singular matrix, and is the left singular matrix. And denotes the diagonal matrix of.

If it is (), a reception vector can be constructed. Thus, and, and So, where the th and th values have nonzero values. Is a vector of dimensions, where the first and second values also have nonzero values. Thus,, where is the singular value of.

Subsequently, the reconstruction signal for may be expressed as in Equation 17 below.

[ Equation 17 ]

Here it is. The SINR values of and calculated using can be expressed by Equation 18 below.

[ Equation 18 ]

Here it is. Therefore, using and can be estimated as. Is defined as the estimation matrix for. Therefore, the orthogonal beamforming matrix can be expressed as Equation 19 below.

[수학식 19]

[ Equation 19 ]

Where and Therefore, the SINR value in this case is

3 is a flowchart illustrating the overall flow of a method for generating a beamforming matrix of a base station according to an embodiment of the present invention. Hereinafter, a process performed at each step will be described with reference to FIG. 3.

First, in step S300, the first signal formed using the non-orthogonal beamforming matrix is transmitted to the plurality of terminals.

In operation S305, a second signal including feedback information about the first signal is received from at least one terminal.

In this case, the base station 200 receives the second signal from a terminal having an estimated transmission capacity estimated using the n signal-to-noise ratios of at least one terminal having a value larger than a preset transmission capacity threshold.

In more detail, each terminal estimates based on the SINR estimated using the first signal to estimate the expected transmission capacity, and through this, the base station 200 estimates the terminal's own transmission when using the service. Estimate the dose.

Thereafter, as shown in Equation 20 below, only the terminal having a value whose estimated transmission capacity is larger than the transmission capacity threshold will transmit the second signal to the base station 200.

[수학식 20]

[ Equation 20 ]

은 k번째 단말기의 예상 전송 용량,here,

Is the estimated transmission capacity of the kth terminal,

은 전송 용량 임계치를 각각 의미한다.

Denotes a transmission capacity threshold, respectively.

Subsequently, in step S310, the terminal that transmits the largest SINR value is selected based on the SINR value included in the second signal. The selection of the terminal can be expressed as Equation 21 below.

[ Equation 21 ]

Here u denotes a set of terminals likely to be selected by the base station 200.

In step S315, an orthogonal beamforming matrix is generated for the selected terminal based on the SINR value of the selected terminal.

In step S320, the base station 200 further selects a terminal having the largest orthogonality value among terminals whose orthogonality with the selected first terminal is greater than or equal to a preset orthogonal threshold. Orthogonality may be expressed as Equation 22 below.

[수학식 22]

[ Equation 22 ]

Here, the base station 200 removes the previously selected terminal from the selectable terminal set, and calculates. If is set to, since is a high sum rate can be obtained. In this case, when there are two transmitting antennas, it can be obtained with high probability.

Therefore, in this case, it is more advantageous to service a plurality of terminals than to service a single terminal. On the other hand, it is difficult to obtain high transmission capacity because of the low orthogonality between and. Therefore, in this case, it is more advantageous to service one terminal.

As such, the base station 200 determines whether to serve a single terminal or multiple terminals. If a terminal having a high correlation with the base station 200 is found, since a higher transmission capacity can be obtained using the terminal, if the value of the terminal having the largest orthogonality variable value in the terminal set is greater than the orthogonal threshold, Is set and the terminal is additionally selected.

When a plurality of terminals are selected in the base station 200, in step S325, beamforming metrics for communication with the plurality of terminals are generated, but zero-forcing beam forming to reduce interference between the plurality of selected terminals. Method to generate the beamforming matrix.

The generation of the beamforming matrix may be expressed as in Equation 23 below.

[수학식 23]

& Quot; (23 ) & quot ;

Here, denotes a transmission vector at the base station 200. If is used for a single terminal in the base station 200, the interference effect between the transmission vectors does not occur, but if the base station 200 serves a plurality of terminals, the transmission is performed. Since interference between vectors occurs, the base station 200 may reduce the influence of the interference between the transmission vectors by configuring a using a zero-forcing beam forming scheme.

The zero forcing beamforming method is an algorithm for obtaining a multi-user diversity gain, and details of the zero forcing beamforming algorithm are obvious to those skilled in the art and will be omitted.

4 is a diagram illustrating an example of a communication system according to an embodiment of the present invention.

개의 송신 안테나(401)를 구비하고 있다.4, the configuration of the base station 200 and the k-th terminal 420 is shown, the base station 200 is

Two transmitting antennas 401 are provided.

개의 송신 안테나(401)를 통해 k번째 단말기(420)에 전송한다.The base station 200 receives the first signal formed using the non-orthogonal beamforming matrix.

It transmits to the k-th terminal 420 through the transmitting antenna 401.

개의 수신 안테나(421)를 통해 제1 신호를 수신하고, 피드백 정보 생성부(423)는 제1 신호를 이용하여 추정된 SINR 및 SINR 간 위상 차 부호를 포함하는 제2 신호를 기지국(200)으로 전송한다.k-th terminal 420

The first signal is received through the two receiving antennas 421, and the feedback information generator 423 sends the second signal including the phase difference code between the SINR and the SINR estimated using the first signal to the base station 200. send.

The terminal selecting unit 205 of the base station 200 selects a terminal using second signals received from the plurality of terminals, and the matrix forming unit 207 uses the orthogonal beamforming matrix based on the SINR information of the selected terminal. Will generate

Thereafter, the base station 200 performs data communication with the selected terminal using an orthogonal beamforming matrix.

FIG. 5 is a graph illustrating average transmission capacity according to SNR values when two transmitting and receiving antennas are serviced and a single terminal is serviced according to an embodiment of the present invention.

In FIG. 5, an Opportunistic BF scheme, a Quantized Selection (QS) scheme, and a conventional RBF scheme are compared with a single terminal selection scheme (SU-RBF NOBM) and a multiple terminal selection scheme (MU-RBF NOBM).

According to an embodiment of the present invention, the terminal is divided into a case of feeding back only SINR and a case of additionally feeding back 1 bit for a phase difference code value of the SINR. For the sake of fair comparison, the existing techniques also show the performance of additional feedback of 1 bit.

Referring to FIG. 5, it can be seen that the single terminal selection technique (SU-RBF NOBM) and the multiple terminal selection technique (MU-RBF NOBM) perform better than the conventional techniques.

FIG. 6 is a graph illustrating an average transmission capacity according to an SNR value when serving a single terminal when two transmitting and receiving antennas are provided according to an embodiment of the present invention.

Referring to FIG. 6, it can be seen that the single terminal selection technique (SU-RBF NOBM) and the multiple terminal selection technique (MU-RBF NOBM) according to an embodiment of the present invention exhibit better performance than the conventional techniques. .

7 is a graph illustrating an average transmission capacity according to the number of terminals when two transmitting and receiving antennas according to an embodiment of the present invention.

PU2RC is a representative multi-antenna transmission technique serving multiple terminals. Referring to FIG. 7, when the number of terminals is small, the single terminal selection technique (SU-RBF NOBM) and the multi-terminal selection technique (MU-RBF NOBM) proposed by the present invention show better performance, and the number of terminals is almost the same. You can see that.

8 is a graph illustrating an average transmission capacity according to the number of terminals when four transmitting and receiving antennas according to an embodiment of the present invention.

Referring to FIG. 8, when the number of terminals is small, when a single terminal selection technique (SU-RBF NOBM) and a multiple terminal selection technique (MU-RBF NOBM) according to an embodiment of the present invention exhibit better performance, and the number of terminals increases, You can see almost the same performance.

9 is a graph showing an average SINR feedback number according to the number of terminals according to an embodiment of the present invention.

Referring to FIG. 9, when there are two transmit / receive antennas, the conventional RBF scheme feeds back twice as many terminals, and the other schemes feed back as many terminals. However, the proposed technique does not perform feedback when the SINR value is lower than a specific reference value. Therefore, as the number of terminals increases, the average feedback number becomes smaller than other techniques.

In addition, embodiments of the present invention may be implemented in the form of program instructions that can be executed through various computer means and recorded on a computer readable medium. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. The program instructions recorded on the medium may be those specially designed and constructed for the present invention or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks, and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Examples of program instructions, such as magneto-optical and ROM, RAM, flash memory and the like, can be executed by a computer using an interpreter or the like, as well as machine code, Includes a high-level language code. The hardware device described above may be configured to operate as at least one software module to perform the operations of one embodiment of the present invention, and vice versa.

In the present invention as described above has been described by the specific embodiments, such as specific components and limited embodiments and drawings, but this is provided to help a more general understanding of the present invention, the present invention is not limited to the above embodiments. For those skilled in the art, various modifications and variations are possible from these descriptions. Accordingly, the spirit of the present invention should not be construed as being limited to the embodiments described, and all of the equivalents or equivalents of the claims, as well as the following claims, belong to the scope of the present invention .

블록
103: 랜덤 빔형성 생성기105: 송신 안테나
110: k번째 단말기111: 수신 안테나
113:

블록115: 채널 추정 및 SVD 블록
117: SINR 측정 블록
200: 기지국201: 송신부
203: 수신부205: 단말기 선택부
207: 메트릭스 생성부
401: 송신 안테나420: k번째 단말기
421: 수신 안테나423: 피드백 정보 생성부200: base station 101:

block
103: random beamforming generator 105: transmit antenna
110: k-th terminal 111: receiving antenna
113:

Block 115: Channel Estimation and SVD Blocks
117: SINR measurement block
200: base station 201: transmitter
203: receiver 205: terminal selector
207: matrix generator
401: transmitting antenna 420: k-th terminal
421: receiving antenna 423: feedback information generation unit

Claims (13)

A base station having n transmit antennas, wherein n is two or more natural numbers,
A transmitter for transmitting a first signal formed by using a non-orthogonal beam forming matrix to a plurality of terminals through the plurality of transmit antennas;
A receiving unit receiving a second signal including feedback information on the first signal from at least one terminal;
A terminal selector which selects at least one terminal to communicate using the second signal; And
A matrix generator configured to generate a beamforming matrix for data transmission to the selected at least one terminal by using the second signal;
And the feedback information comprises a phase difference code between the n signal-to-noise ratios (SINRs) and the n signal-to-noise ratios estimated using the first signal at each of the at least one terminal. delete The method of claim 1,
The receiving unit
And receiving the second signal from a terminal having an estimated transmission capacity estimated using the n signal-to-noise ratios of the at least one or more terminals having a value larger than a preset transmission capacity threshold. The method of claim 3,
The terminal selector
And selecting a first terminal transmitting the largest signal-to-noise ratio (SINR) among the terminals transmitting the second signal. 5. The method of claim 4,
The matrix generator
And generating the orthogonal beamforming matrix for the first terminal using the magnitude, phase, and phase difference code extracted from the n signal-to-noise ratios. 5. The method of claim 4,
The terminal selector
And selecting a second terminal having an orthogonality with the selected first terminal more than a preset orthogonal threshold value among the terminals transmitting the second signal. The method according to claim 6,
The matrix generator
When the second terminal is additionally selected in addition to the first terminal
Generate a beamforming matrix for communication with the first terminal and the second terminal,
And generating the beamforming matrix using a zero-forcing beamforming scheme to reduce interference between a plurality of selected terminals. In the terminal,
A terminal receiver for receiving a first signal formed using a non-orthogonal beamforming matrix from a base station having n transmit antennas, wherein n is a natural number of two or more;
A feedback information generator configured to generate feedback information on the first signal; And
A terminal transmitter for transmitting the feedback information to the base station,
And the feedback information comprises a phase difference code between the n signal-to-noise ratios (SINRs) and the n signal-to-noise ratios estimated using the non-orthogonal beamforming matrix. 9. The method of claim 8,
The transmitting unit
And transmitting the feedback information to the base station when the estimated transmission capacity estimated using the n signal-to-noise ratios has a value larger than a preset transmission capacity threshold. A method of generating a beamforming matrix of a base station having n transmit antennas, wherein n is two or more natural numbers,
Transmitting a first signal formed using a non-orthogonal beamforming matrix to a plurality of terminals via the plurality of transmit antennas;
Receiving from the at least one terminal a second signal comprising feedback information for the first signal;
Selecting at least one terminal to communicate using the second signal; And
Generating a beamforming matrix for data transmission to the selected one or more terminals using the second signal;
The feedback information includes a method for generating a beamforming matrix of a base station, wherein the at least one terminal includes a phase difference code estimated between the n signal-to-noise ratios (SINRs) and the n signal-to-noise ratios using the first signal. . delete The method of claim 10,
The step of selecting the terminal
Selecting a first terminal that transmits the largest signal-to-noise ratio (SINR) among the terminals that transmit the second signal; And
Further selecting the second terminal when a second terminal having an orthogonality with respect to the selected first terminal is greater than or equal to a preset orthogonal threshold among the terminals transmitting the second signal;
Method for generating a beamforming matrix of the base station comprising a. The method of claim 12,
Generating the beamforming matrix
Generating an orthogonal beamforming matrix for communication with the first terminal when only the first terminal is selected in the base station;
When the second terminal is additionally selected in addition to the first terminal, generating a beamforming matrix for communication with the first terminal and the second terminal by using a zero-forcing beam forming method. A method for generating a beamforming matrix of a base station.

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