KR102114837B1 - Method and apparatus for transmitting and receiving a signal in a wireless communication system - Google Patents

Abstract

In the present invention, in a wireless communication system, a receiver receives a plurality of signals from a transmitter using a plurality of antennas, estimates a gain and an angle of angle (Agle of Departure) for at least one of the plurality of signals, and Sort the indexes for the signal gains in a large order, and based on the aligned indexes, sort the information related to the launch angles for each of the plurality of signals in the order of the signal gains, and at least one of the information related to the sorted launch angles. One is sent to the transmitter as feedback information.

Description

Method and apparatus for transmitting / receiving signals in a wireless communication system {METHOD AND APPARATUS FOR TRANSMITTING AND RECEIVING A SIGNAL IN A WIRELESS COMMUNICATION SYSTEM}

The present invention relates to a method and apparatus for transmitting and receiving signals in a wireless communication system.

When conventional pre-coder (ZF) and regularized zero-forcing (RZF) techniques are used, the transmitter must acquire information on all channels used by each receiver. Accordingly, in an environment in which massive multiple input multiple output (MIMO) is easy to use, such as a millimeter wave (mmWave) communication system, the burden of transmitting and receiving a large number of feedback information increases. In addition, as power of a transmission signal is allocated differently for each antenna, radio frequency (RF) -chain as many as the number of transmission antennas is required, and thus, there is a problem in that a hardware cost is high in an mmWave environment.

In consideration of these problems, methods that use information such as signal gain on the mmWave channel, angle of departure (hereinafter referred to as 'AOD') and angle of arrival (hereinafter referred to as 'AOA') are used. Is being proposed. Among the above methods, there are a beam steering method and a null steering method.

The beam steering method is a method in which a transmitter transmits a beam in a desired direction based on AOD information. However, since the beam steering method does not consider interference with other receivers, it can be effectively used in a single-user environment, but is not suitable in a multi-user environment. Therefore, when the beam steering method is used in a multi-user environment, there is a disadvantage in that the overall rate of the receiver is reduced.

On the other hand, the null adjustment method provides a interference control effect as a method of preventing a transmitter from transmitting a beam in an unwanted direction based on AOD information. However, when the null adjustment method is used indiscriminately in a wireless communication environment in which multiple users and multiple signals are formed, there is a problem in that a transmission power must be amplified as a null is formed in a similar direction.

The present invention proposes a method and apparatus for transmitting and receiving signals in a wireless communication system.

In addition, the present invention proposes a method and apparatus for controlling interference while reducing the amount of feedback information while using fewer RF chains than the number of antennas in a wireless communication system.

In addition, the present invention proposes a method and apparatus for improving a transmission rate while preventing a power amplification phenomenon of a null adjustment type preprocessor in a multi-user mmWave environment.

The method proposed in the present invention; In a signal transmission method of a transmitter in a wireless communication system, a process of transmitting a plurality of signals to a receiver using a plurality of antennas, and an angle of departure information for at least one of the plurality of signals are received from the receiver If it is, the process of determining a signal transmission direction based on the launch angle information, the process of transmitting a signal using a predetermined transmission power in the determined signal transmission direction, and the signal transmission direction other than the determined signal transmission direction is null It includes a process of performing (null) transmission, and the launch angle information includes launch angle information for at least one of the plurality of signals arranged in order of large signal gain.

The device proposed by the present invention; In a transmitter in a wireless communication system, a plurality of antennas, a transmitter for transmitting a plurality of signals to a receiver using the plurality of antennas, and an angle of launch (Angle of Departure) information for at least one of the plurality of signals from the receiver When receiving the launch angle information, and the launch angle information, determines a signal transmission direction based on the launch angle information, controls the transmitter to transmit a signal using a predetermined transmission power in the determined signal transmission direction, and the determined It includes a control unit for performing null transmission in the signal transmission direction other than the signal transmission direction, and the launch angle information includes launch angle information for at least one of the plurality of signals arranged in order of large signal gain.

The present invention can control interference while reducing the amount of feedback information while using fewer RF chains than the number of antennas in a wireless communication system. In addition, the present invention has the advantage of improving the transmission rate while preventing the power amplification phenomenon of the null adjustment type preprocessor in a multi-user mmWave environment.

1 is a graph showing transmission power for each transmission direction of a transmitter in a wireless communication system in which a general null adjustment method is used,
2 is a view showing a wireless communication system according to an embodiment of the present invention,
3 is a view showing a transmitter and a receiver of a wireless communication system according to an embodiment of the present invention,
4 is a view showing a process of transmitting feedback information to a plurality of receivers according to an embodiment of the present invention,
5 is a graph showing transmission power for each transmission direction of a transmitter according to an embodiment of the present invention,
6 is a view showing a baseband precoder and an RF chain unit configured based on a null steering beamformer according to an embodiment of the present invention,
7 is a flowchart illustrating the operation of a receiver according to an embodiment of the present invention,
8 is a flowchart illustrating an operation of a transmitter according to an embodiment of the present invention.
9 is a graph showing performance according to an interference control method according to an embodiment of the present invention.

Hereinafter, the operation principle of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, when it is determined that detailed descriptions of related known functions or configurations may unnecessarily obscure the subject matter of the present invention, detailed descriptions thereof will be omitted. In addition, terms to be described later are terms defined in consideration of functions in the present invention, which may vary according to a user's or operator's intention or practice. Therefore, the definition should be made based on the contents throughout this specification.

The present invention provides an interference control method and apparatus in a wireless communication system.

Prior to the description of the embodiment of the present invention, a null steering method generally used for interference control will be described.

)과 신호를 송신하기 원하지 않는 방향(

)을 동시에 고려하여 간섭을 제어하는 방식이다. 상기 송신기가 신호를 송신할 수 있는 각 방향을 어레이 벡터(array vector)를 사용하여 행렬 N으로 나타내면 다음 수학식 1과 같다.The null adjustment method is a direction in which the transmitter wants to transmit a signal (

) And the direction in which you do not want to transmit the signal (

) At the same time to control interference. When each direction in which the transmitter can transmit a signal is represented by a matrix N using an array vector, Equation 1 is given.

When the matrix N is determined as described above, a null steering vector (f) may be determined based on Equations 2 and 3 below.

In Equations 2 and 3, H denotes Hermitian operation, and ⁺ denotes a pseudo inverse. In addition, in Equations 2 and 3, the transmission power of the first array vector is set to 1, and the remaining transmission power is set to 0, as an example.

When the null adjustment vector is determined, the transmitter performs null transmission in a corresponding direction and transmits a signal in the other direction based on the determined null adjustment vector. This will be described in detail with reference to FIG. 1 as follows.

1 is a graph showing transmission power for each transmission direction of a transmitter in a wireless communication system in which a general null adjustment method is used.

,

)(100, 120)을 결정한다. 그리고 상기 송신기는 상기 결정된 방향(

,

)(100, 120)에서 널 송신을 수행한다. In the graph illustrated in FIG. 1, the horizontal direction represents an angle of angle (hereinafter referred to as “AOD”), and the vertical direction represents transmission power. Referring to FIG. 1, when a null steering vector is determined, the transmitter should perform a null transmission based on the determined null steering vector (

,

) (100, 120). And the transmitter is the determined direction (

,

) (100, 120) to perform a null transmission.

,

)(100, 120)을 제외한 나머지 방향 중 신호를 송신하기 원하는 방향(

)(140)에서는 가장 큰 송신 전력을 사용하여 신호를 송신한다. 여기서 상기 널 송신이라는 것은 송신 전력을 0으로 설정하는 것을 의미할 수 있다. In addition, the transmitter is the determined direction (

,

) (100, 120), the direction in which you want to transmit the signal (

) 140, the signal is transmitted using the largest transmission power. Here, the null transmission may mean setting the transmission power to 0.

As described above, the transmitter performs null transmission in an undesired direction and transmits a signal with the greatest intensity in the desired direction, so that it can accurately transmit a signal to the corresponding receiver while controlling interference to other receivers.

In an embodiment of the present invention, a method for improving a sum rate while preventing power amplification of a preprocessor in a multi-user millimeter wave (mmWave) communication environment using the null adjustment method as described above present.

A wireless communication system according to an embodiment of the present invention is as shown in FIG. 2.

2 is a view showing a wireless communication system according to an embodiment of the present invention.

Referring to FIG. 2, the wireless communication system may include a transmitter 200 and a plurality of receivers, for example, receiver 1 210, receiver 2 220 and receiver 3 230. The transmitter 200 may be a base station that transmits signals, and the receiver 1 210, receiver 2 220 and receiver 3 230 may be mobile terminals that receive signals from the base station. The receiver 1 210, the receiver 2 220 and the receiver 3 230 are located at different locations. Accordingly, the directions in which the receiver 1 210, the receiver 2 220, and the receiver 3 230 receive signals transmitted by the transmitter 200 are also different.

For example, the receiver 1 210 may receive a signal transmitted in the θ ₁ direction among signals transmitted by the transmitter 200, and the receiver 2 220 may be a signal transmitted by the transmitter 200 Among them, a signal transmitted in the θ ₂ direction may be received, and the receiver 3 230 may receive a signal transmitted in the θ ₃ direction among signals transmitted by the transmitter 200.

Accordingly, the transmitter 200 may receive feedback information including AOD information for each signal from each receiver, determine a direction in which to transmit the signal, and transmit a signal using the largest transmission power in the corresponding direction. . In addition, in the direction in which the transmitter 200 interferes with other receivers, interference may be controlled by using the null adjustment method described above.

3 is a view showing a transmitter and a receiver of a wireless communication system according to an embodiment of the present invention.

FIG. 3 shows an example of a transmitter and a receiver included in the wireless communication system as shown in FIG. 2. Referring to FIG. 3, each of the transmitter 300 and the plurality of receivers 320-1 to 320-K may perform communication using a plurality of antennas. And although not shown in FIG. 3, the transmitter 300 and the plurality of receivers 320-1 to 320-K each store a memory for storing various data and information generated by performing the wireless communication, and the transmitter And a control unit for controlling the overall operation of each of the plurality of receivers.

The transmitter 300 has N _t transmit antennas, and the plurality of receivers 320-1 to 320-K used by K users each have N _r transmit antennas. The transmitter 300 has N _RF of radio frequency: may transmit a full-N _ts transmit streams through (Radio Frequency RF) chain (chain) unit (310-1 ~ 310- N _RF). In addition, the plurality of receivers 320-1 to 320-K may receive N _s streams through respective channels ( H ₁ ... H _K , where H _K represents a channel of the K- th receiver).

On the other hand, if the channel ( H _k ) of the k- th receiver among the total K receivers (320-1 to 320-K) has L signals (ray), it is expressed by Equation 4 below.

은 k번째 수신기의 l번째 신호에 대한 이득(gain)을 나타내고,

는 k번째 수신기의 l번째 신호에 대한 AOD를 나타내고,

은 k번째 수신기의 l번째 신호에 대한 도래각(Angle of Arrival)(이하 'AOA'라 칭함)를 나타내고, H는 허미시안 연산을 나타낸다. 그리고 상기 수학식 4에서 어레이 벡터인 a _r (θ) 및 a _t (θ) 는 각각 다음 수학식 5 및 6에 나타난 바와 같이 균일 선형 배열(Uniform Linear Array: ULA) 형태로 구성될 수 있다. In Equation 4 above

Denotes the gain for the l- th signal of the k- th receiver,

Denotes the AOD for the l- th signal of the k- th receiver,

Denotes the angle of arrival (hereinafter referred to as 'AOA') for the l th signal of the k th receiver, and H denotes the Hermitian operation. In addition, the array vectors a _r (θ) and a _t (θ) in Equation 4 may be configured in the form of a Uniform Linear Array (ULA) as shown in Equations 5 and 6, respectively.

In Equations 5 and 6, d denotes an antenna spacing, and λ denotes a wave length of a signal.

In the transmitter, the signal s: [ N _ts ⅹ1] corresponding to the total number of streams ( N _ts = N _s ⅹ K ) is a baseband precoder ( F _bb : [ N _RF ⅹ N _ts ]) (300) And RF chain ( F _RF : [ N _t ⅹ N _RF ]) (310-1 ~ 310- N _RF ). Here, the baseband precoder 300 and the RF chain parts 310-1 to 310- N _RF , which may be collectively referred to as a pre-processing part, may be represented by a component represented by a single matrix. In the embodiment of the present invention, it is defined as a null steering beamformer ( F _null : [ N _t ⅹ N _ts ]) and is represented by Equation 7 below.

In Equation 7, f _{k, 1} denotes the first stream to be transmitted to the k th receiver, f _{k, 2} denotes the second stream to be transmitted to the k th receiver, and f _{k, Ns} to be transmitted to the k th receiver N _s th stream.

를 통해 하기 다음 수학식 8과 같은 수신 신호를 획득할 수 있다.When the transmitter transmits a signal of F _null to K receivers, the k- th receiver receives the corresponding signal through a plurality of antennas, and a combiner

Through the received signal as shown in Equation 8 below can be obtained.

In Equation 8, y _k denotes a received signal of the k- th receiver, and n _k denotes a noise received by the k- th user.

In an embodiment of the present invention, a method is proposed in which interference control can be performed using the null-adjusted beamformer defined as above. Hereinafter, the interference control method proposed in the embodiment of the present invention will be described in detail.

4 is a diagram illustrating a process in which a plurality of receivers transmit feedback information to a transmitter according to an embodiment of the present invention.

4, K receivers 420-1 to 420-K respectively transmit AOD information as feedback information to a transmitter including the null steering beamformer 400. The K receivers (420-1 ~ 420-K) shown in Figure 4 may correspond to the K receivers (320-1 ~ 320-K) shown in Fig. The process of transmitting the feedback information will be described in detail as follows.

First, of the K receivers 420-1 to 420-K, the k- th receiver receives L signals from the transmitter and estimates gain, AOD, and AOA for the L signals. In addition, the k- th receiver sorts the indexes for the L signals in the order in which the gain for the L signals is large, and stores index information according to the sorted order. Here, the stored index information Q _k may be expressed as Equation 9 below.

Equation (9) shows that the indexes of L signals for the k- th receiver are arranged in order of high signal gain.

Based on the stored index information, the k- th receiver sorts AOA in order of gain for the L signals, and configures a combiner for the k- th receiver based on the aligned AOA information. The combiner may be configured based on Equation 10 below.

는 상기 k번째 수신기가 수신한 신호에 대한 AOA를 나타낸다.In Equation 10, W _{k, i} denotes a combined signal for signals (eg, N _S streams) received by the k th receiver through a plurality of antennas, and a _r () denotes an array vector,

Denotes AOA for the signal received by the k- th receiver.

Subsequently, the k- th receiver sorts AOD in order of gain for the L signals. Then, the k- th receiver feeds the aligned AOD information to the transmitter. Here, when the feedback AOD information is expressed by Equation 11, Equation 11 below is expressed.

는 상기 k번째 수신기가 피드백하는 AOD 정보를 나타내고, B는 상기 k번째 수신기가 피드백하는 AOD 정보의 개수를 나타낸다

. 상기 L개의 신호 전체에 대한 AOD 정보가 피드백되면 피드백량이 많아지게 되므로, 상기 B는 통신 환경에 따라 다양하게 조정될 수 있다. In Equation 11 above

Denotes AOD information fed back by the k- th receiver, and B denotes the number of AOD information fed back by the k- th receiver.

. When the AOD information for all the L signals is fed back, the amount of feedback increases, so the B can be adjusted in various ways depending on the communication environment.

When the AOD information is fed back from all of the K receivers 420-1 to 420-K, the transmitter may determine a null adjustment vector for the i th stream of the k th receiver using the fed back AOD information.

이고 m > 1이면, 널에 대한 어레이 벡터는

와 같이 나타낼 수 있다. 그러면 상기 송신기는 어레이 벡터들로 구성된 행렬 N _k,i 를 다음 수학식 12와 같이 나타낼 수 있다.First, a matrix N _{k, i} ( m ) consisting of array vectors is defined as representing the m- th column vector of N _{k, i} , and the array vector for the transmission direction is

And m > 1, the array vector for null is

Can be represented as Then, the transmitter may express a matrix N _{k, i} composed of array vectors as in Equation 12 below.

Then, the transmitter may _calculate the null adjustment vector based on Equations 13 to 15 using N _{k, i} , and finally determine the transmit power.

When the above process is performed, a result as shown in FIG. 5 may appear.

5 is a graph showing transmission power for each transmission direction of a transmitter according to an embodiment of the present invention.

Referring to FIG. 5, the array vector N _{k, i} (1) 520 for the transmission direction has the largest transmission power, and the array vector for null (hereinafter referred to as the “null vector”) N _{k , i} ( m ) 500 can be seen to have the smallest transmission power (eg, transmission power is set to 0).

의 크기가 커져 정규화로 인한 성능 열화 현상이 나타남을 의미한다. 이를 방지하기 위해 N _k,i 구성 시 상관(correlation) 값이 어레이 벡터를 제외시키는 방안이 필요하다. 이를 위해 본 발명의 실시 예에서는 하기 수학식 16을 사용한다. On the other hand, in the process of calculating the null adjustment vector, if a similar array vector (ie, an array vector having similar directions) is present, the minimum eigen-value of N _{k, i} appears as a very small value. This results in the maximum eigen-value diverging in the process of calculating the pseudo inverse matrix N _{k, i} ⁺ .

It means that the performance deterioration due to normalization appears due to the increase in the size of. In order to prevent this _, a method of excluding the array vector whose correlation value is required when constructing N _{k, i} is necessary. For this, in the embodiment of the present invention, Equation 16 below is used.

Equation 16 shows that when determining a new null vector, the correlation value with the previously constructed array vector is compared, so that the corresponding array vector can be used when the correlation value is less than or equal to a specific threshold.

가 결정되면, 널 조정 벡터의 특성에 따라 각 벡터의 엘리먼트(element)의 크기가 서로 비슷한 크기의 범위를 가짐을 알 수 있다. 이러한 특성을 기반으로 널 조정 빔포머(F _null )를 하이브리드(hybrid) 빔포밍 시스템에 적용하기 위해 하기 수학식 17 내지 19가 사용될 수 있다.Meanwhile, the null adjustment vector for the streams of all receivers

When is determined, it can be seen that the size of the elements of each vector has a similar size range according to the characteristics of the null adjustment vector. Based on these characteristics, the following equations 17 to 19 may be used to apply a null steering beamformer ( F _null ) to a hybrid beamforming system.

Since the RF chain portion of the transmitter includes a phase shift, elements in the RF chain portion cannot have a size. Accordingly, as shown in Equation 17, the RF chain part F _RF may be configured to include elements based on a phase component of a _null steering beamformer F _null .

In addition, the baseband precoder ( F _BB ) may include elements determined by performing a pseudo inverse matrix operation of a matrix including elements of the RF chain, as shown in Equation 18 above. This method can be applied because the elements of the null adjustment vector have similar size values, and it can be confirmed that the baseband precoder includes diagonal matrix elements.

As a result, the RF chain portion ( F _RF ) and the baseband precoder ( F _BB ) may include elements similar to the _null steering beamformer ( F _null ) as shown in Equation 19. If this is represented by a drawing, it is as shown in FIG. 6.

6 is a view showing a baseband precoder and an RF chain unit configured based on a null steering beamformer according to an embodiment of the present invention. As shown in FIG. 6, the baseband precoder 620 and the RF chain part 640 may include elements similar to the null steering beamformer 600. When such a configuration is used, the number of RF chains can be reduced by the total number of streams smaller than the number of antennas.

Next, the operation of the transmitter and the receiver according to an embodiment of the present invention will be described with reference to FIGS. 7 and 8, respectively.

7 is a flowchart illustrating an operation of a receiver according to an embodiment of the present invention.

Referring to FIG. 7, in step 700, the receiver receives L signals from the transmitter. In addition, the receiver estimates gain, AOA and AOD for the L signals in step 702.

Subsequently, in step 704, the index information for the L signals is sorted and stored in the order of highest signal gain. In step 706, the receiver sorts the AOA in order of large signal gain and combines the received signals based on the stored index information.

In step 708, the AOD sorts the AOD in the order of the highest signal gain based on the stored index information, and feeds back the information on the aligned AOD to the transmitter.

8 is a flowchart illustrating an operation of a transmitter according to an embodiment of the present invention.

Referring to FIG. 8, in step 800, the transmitter receives AOD information arranged in order of large signal gain from K receivers. In step 802, the transmitter configures an array matrix for each stream of the K receivers.

In step 804, the transmitter compares the correlation values of the vectors constituting the array matrix with a threshold value. Then, in step 806, if the correlation value is smaller than a threshold, the transmitter proceeds to step 808 to calculate a null adjustment vector for each stream of the K receivers.

In step 810, the transmitter determines a radio processing operation using the phase component of the null adjustment vector. Subsequently, in step 812, the transmitter determines a baseband processing operation based on the null adjustment vector and the radio processed vector, and transmits a signal according to the determined baseband processing operation and radio processing operation in operation 814.

9 is a graph showing performance according to an interference control method according to an embodiment of the present invention.

)를 가지며, AOD(

)의 분포는 각 수신기의 중심 각도(θ _k )에서 균등 분포(uniform distribution)

를 갖도록 한다. 그리고 AOA(

)의 분포는 채널의 산란(scattering) 특성에 의해 결정되므로,

로 설정된 경우 신호의 개수는 4~10개 사이로 발생시켜 그 성능을 살펴보았다. The channel environment for examining the effect according to the embodiment of the present invention is a signal-based channel structure having a strong line of sight (LOS) component (

), And AOD (

) Is distributed uniformly at the central angle ( θ _k ) of each receiver.

To have. And AOA (

) Distribution is determined by the scattering characteristics of the channel,

When set to, the number of signals was generated between 4 and 10 and the performance was examined.

Referring to (a) and (b) of FIG. 9, it can be seen that the sum rate is gradually increased as the SNR is increased because interference is not taken into account when the beam steering method is used (see Beam steering graph). .

In addition, when a general null adjustment method considering interference is used, there is an effect of removing interference at a high SNR, but it can be seen that a performance degradation phenomenon occurs in the process of normalizing the power of the preprocessor (see Null steering graph).

If a null adjustment scheme based on correlation according to an embodiment of the present invention is considered in consideration of this, an effect of reducing performance degradation may be obtained (see a null steering (corr) graph).

On the other hand, the null adjustment method described above is a baseband based null adjustment method, and when the null adjustment method is applied to a hybrid beamforming system, the number of RF chains is about 64 (number of antennas) from 8 to 8 than the baseband based null adjustment method. It is reduced to (number of users). Here, performance degradation due to approximation may exist, but interference cancellation effect can be seen to some extent.

 9 (b) compared to FIG. 9 (a), in an environment where the number of feedback signals is larger, the null adjustment method may have higher performance, and the performance gain due to the correlation-based selection method also increases. There is this.

On the other hand, in the detailed description of the present invention, although specific embodiments have been described, various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of claims to be described later, but also by the scope and equivalents of the claims.

Claims (20)

A method for transmitting a signal from a transmitter in a wireless communication system,
A process of transmitting a plurality of signals to a receiver using a plurality of antennas,
Determining the signal transmission direction based on the launch angle information, when the launch angle information of at least one of the plurality of signals is received from the receiver;
Transmitting a signal using a predetermined transmission power in the determined signal transmission direction,
And performing a null transmission in the remaining signal transmission directions except for the determined signal transmission direction,
The launch angle information includes launch angle information for at least one of the plurality of signals arranged in the order in which signal gain is large,
The step of transmitting the signal includes the step of transmitting the signal using a null steering beamformer, wherein the null steering beamformer is based on a null steering vector determined for each receiver and vector information for radio processing. Baseband precoding operation and radio processing operation based on phase information of the null adjustment vector,
The null adjustment vector is a signal transmission method characterized in that it represents an array vector according to the signal transmission direction and direction information to perform null transmission. According to claim 1,
The process of performing the null transmission,
And setting the transmission power in the remaining signal transmission direction to zero. According to claim 1,
The process of determining the signal transmission direction,
And determining a signal transmission direction based on launch angle information for a signal having the largest signal gain among the plurality of signals. According to claim 1,
The process of determining the signal transmission direction,
Determining an array matrix for the plurality of signals,
Calculating a correlation value between vectors included in the array matrix,
And determining the signal transmission direction based on the calculated correlation value. The method of claim 4,
The process of determining the signal transmission direction based on the calculated correlation value,
Comparing the calculated correlation value with a threshold value,
Excluding at least two of the vectors from the array matrix based on the comparison result,
And determining the signal transmission direction based on the array matrix from which the at least two vectors are excluded. The method of claim 4,
The process of calculating the correlation value between the vectors included in the array matrix is
And calculating a correlation value between vectors corresponding to signals allocated to directions adjacent to each other among the vectors included in the array matrix. According to claim 1,
The process of determining the signal transmission direction,
Detecting a second direction adjacent to the first direction among the plurality of signal transmission directions;
Calculating a correlation value between signals allocated to the first direction and the second direction,
And determining to use the second direction as a signal transmission direction according to whether the calculated correlation value is smaller than a preset value. According to claim 1,
The null adjustment beamformer,
Includes a baseband precoder and a radio frequency chain,
The radio frequency chain unit performs a radio processing operation based on phase information of a null adjustment vector determined for each receiver,
The baseband precoder is a signal transmission method for performing a baseband precoding operation based on the null adjustment vector and vector information for the radio processing. delete According to claim 1,
The signal transmission method characterized in that the largest transmission power is used in the determined signal transmission direction, and the smallest transmission power is used in the remaining signal transmission direction. In a transmitter in a wireless communication system,
Multiple antennas,
A transmitter for transmitting a plurality of signals to the receiver using the plurality of antennas,
And a receiver for receiving the angle of launch (Angle of Departure) for at least one of the plurality of signals from the receiver,
A signal transmission direction is determined based on the launch angle information, and the transmission unit is controlled to transmit a signal using a preset transmission power in the determined signal transmission direction, and null () in a signal transmission direction other than the determined signal transmission direction null) a control unit that performs transmission and
A baseband precoding operation based on a null adjustment vector determined for each receiver and vector information for radio processing, and a null adjustment beamformer performing a radio processing operation based on phase information of the null adjustment vector. Includes,
The launch angle information includes launch angle information for at least one of the plurality of signals arranged in the order in which signal gain is large,
The null adjustment vector is a transmitter characterized in that it represents an array vector according to signal transmission direction and direction information to perform null transmission. The method of claim 11,
The control unit is a transmitter characterized in that the transmission power in the remaining signal transmission direction is set to zero. The method of claim 11,
The control unit determines the signal transmission direction based on the launch angle information for the signal having the largest signal gain among the plurality of signals. The method of claim 11,
The controller determines an array matrix for the plurality of signals, calculates a correlation value between vectors included in the array matrix, and determines the signal transmission direction based on the calculated correlation value. . The method of claim 14,
The control unit compares the calculated correlation value with a threshold value, excludes at least two of the vectors from the array matrix based on the comparison result, and based on the array matrix from which the at least two vectors are excluded. Transmitter characterized in that to determine the signal transmission direction. The method of claim 14,
The control unit calculates a correlation value between vectors corresponding to signals allocated to directions adjacent to each other among vectors included in the array matrix. The method of claim 11,
The control unit detects a second direction adjacent to the first direction among a plurality of signal transmission directions, calculates a correlation value of signals allocated to the first direction and the second direction, and the calculated correlation value is greater than a preset value. And determining whether to use the second direction as a signal transmission direction depending on whether it is small. The method of claim 11,
The null adjustment vector includes a baseband precoder and a radio frequency chain,
The radio frequency chain unit performs a radio processing operation based on phase information of a null adjustment vector determined for each receiver,
The baseband precoder is a transmitter that performs a baseband precoding operation based on the null adjustment vector and vector information for the radio processing. delete The method of claim 11,
The transmitter characterized in that the largest transmission power is used in the determined signal transmission direction, and the smallest transmission power is used in the remaining signal transmission direction.

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