KR20130017881A - Apparatus and method for designing beamforming in multiple input single output - Google Patents

Abstract

PURPOSE: A beam-forming design device in multi-input and single-output and a method thereof are provided to improve a VSINR(Virtual Signal-to-Interference and Noise Ratio) based on a single user detection method. CONSTITUTION: A voltage calculation unit(210) calculates a diagonal matrix, desired signal voltages, and noise voltages in a receiver by using a weighted transmission ratio and VSINR for a user having a transmitter and the receiver. Coefficient calculation unit(120) calculates a plurality of weighted coefficients using the diagonal matrix calculated by the voltage calculation unit. A beam-forming calculation unit(130) calculates a beam-forming vector of the transmitter using the weighted coefficients calculated by the coefficient calculation unit. The power calculation unit calculates the diagonal matrix in the receiver using the desired signal voltage and the noise voltage in the receiver. [Reference numerals] (120) Coefficient calculation unit; (130) Beam-forming calculation unit; (140) Display unit; (150) Storage unit; (210) Voltage calculation unit

Description

Beamforming Design Apparatus and Method for Multiple Input Single Output {APPARATUS AND METHOD FOR DESIGNING BEAMFORMING IN MULTIPLE INPUT SINGLE OUTPUT}

The present invention relates to a multi-input single output, and more particularly, to an apparatus and method for designing beamforming in a multi-input single output.

The cellular system divides a large service area into small cells and intentionally installs base stations (BSs) that manage the areas so as not to cause interference and interference with each other, thereby improving repetitive use of the same frequency. That's the way. At this time, the base stations are interconnected by a fixed network capable of communicating data between the base stations. A mobile station (MS) is used over a wireless communication link by the base station of the cell in which the mobile station is located.

An ad-hoc network is a temporary network that is configured autonomously by mobile terminals using a wireless interface. The ad-hoc network is autonomously configured by nodes and operates independently of an infrastructure network. Ad-hoc nodes communicate with each other using a wireless interface, overcome the limitations of the communication distance of the wireless interface by the multi-hop routing function, and the network topology is dynamically changed because the nodes are free to move.

Meanwhile, since cellular systems and ad hoc networks are inevitably interference-limited, research on interference channels (ICs) has been important. However, the capacitive region of the interference channel is not fully characterized when there are two users. The best approach achievable in the conventional case is based on rate division taking into account the possibility of Multi User Detection (MUD) at each receiver.

Looking at the conventional patent, Korean Patent No. 10-07063644 describes a technique that can maximize the desired signal while reducing or eliminating interference signals in consideration of interference with other users using multi-user detection. In addition, Korean Patent No. 10-0626214 describes a technique of calculating a data rate for a mobile terminal by combining a multi-user detection method and a single user detection method, and transmitting a signal to the mobile terminal according to the sum of the transmission rates.

However, the conventional patent describes a technique using multi-user detection, and it is very complicated to optimize the transmission power using such multi-user detection. Accordingly, since it is reasonable to design input signals on the assumption of single user detection (SUD) in which each receiver treats interference signals as noise, research on this has been actively conducted in recent years.

Embodiments of the present invention provide an apparatus and method for designing beamforming in a multi-input single output for designing beamforming that maximizes a virtual signal-to-interference and noise ratio (VSINR) based on single user detection. To provide.

In addition, an embodiment of the present invention provides an apparatus and method for beamforming design in a multi-input single output for designing beamforming to maximize the weighted sum rate.

In addition, an embodiment of the present invention provides an apparatus and method for beamforming design in a multi-input single output for designing beamforming using local channel state information (CSI).

According to one aspect of the present invention, an apparatus for designing beamforming at multiple input single output is provided.

According to an embodiment of the present invention, an apparatus for designing beamforming in a multi-input single output includes: a receiver using a weighted sum rate and a virtual signal to interference and noise ratio for a user who pairs a transmitter and a receiver; A power calculation unit for calculating the interference and noise power, a desired signal power, and a diagonal matrix in a; A coefficient calculator for calculating a plurality of weighting coefficients using the diagonal matrix calculated by the power calculator; And a beamforming calculator configured to calculate a beamforming vector of the transmitter using the plurality of weighting coefficients calculated by the coefficient calculator.

In addition, according to an aspect of the present invention, a method of designing a beamforming by a beamforming design apparatus in a multi-input single output is provided.

According to an embodiment of the present invention, in a method of designing beamforming by a beamforming design apparatus in a multi-input single output, a weighted sum rate and a virtual signal to interference and noise ratio for a user who configures a transmitter and a receiver in pairs Calculating interference and noise power, desired signal power, and diagonal matrix at the receiver; Calculating a plurality of weighting coefficients using the calculated diagonal matrix; And calculating a beamforming vector of the transmitter using the calculated plurality of weighting coefficients.

The apparatus and method for beamforming design in a multi-input single output according to an embodiment of the present invention can improve the performance by designing beamforming that maximizes the virtual signal-to-interference and noise ratio and the weighted sum rate based on single-user detection. have.

In addition, the beamforming design apparatus and method of the multi-input single output according to an embodiment of the present invention can reduce the overhead significantly because the beamforming is designed using local channel state information.

1 is a block diagram illustrating an apparatus for designing beamforming in a multi-input single output according to an embodiment of the present invention.
2 is a block diagram schematically illustrating a user according to an embodiment of the present invention.
3 is a flowchart illustrating a beamforming design method according to an embodiment of the present invention.
4 is an exemplary view showing a user according to an embodiment of the present invention.
5 is a flow chart showing a beamforming design method according to another embodiment of the present invention.
6 to 8 are graphs showing simulation results by applying the beamforming design method according to an embodiment of the present invention.

DETAILED DESCRIPTION Hereinafter, an operation principle of an embodiment of a beamforming design apparatus and method in a multi-input single output according to the present invention will be described in detail with reference to the accompanying drawings and the description. It should be understood, however, that the drawings and the following detailed description are exemplary and explanatory of various embodiments for effectively illustrating the features of the present invention. Therefore, the present invention should not be limited to the following drawings and descriptions.

In addition, in the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. In addition, terms to be described below are terms defined in consideration of functions in the present invention, which may vary according to a user's or operator's intention or custom. Therefore, the definition should be made based on the contents throughout the present invention.

In addition, the following embodiments will be used to appropriately modify, integrate, or separate terms, such that those skilled in the art to which the present invention pertains may clearly understand the technical features of the present invention. The present invention is by no means limited thereto.

An embodiment of the present invention to be described later will be described in detail a method of designing beamforming by maximizing a weighted sum rate, a virtual signal-to-interference, and a noise ratio for a user who configures a transmitter and a receiver in pairs. In addition, an embodiment of the present invention will be described in detail a method for designing beamforming by using channel state information of a user.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram illustrating a beamforming design apparatus in a multi-input single output according to an embodiment of the present invention.

Referring to FIG. 1, the beamforming design apparatus 100 may include a power calculator 110, a coefficient calculator 120, a beamforming calculator 130, a display 140, and a storage 150.

The power calculation unit 110 uses a weighted sum rate (WSR) and a virtual signal-to-interference and noise ratio (VSINR) for a user to reduce the interference and noise power of the receiver, Calculate the desired signal power, diagonal matrix. Here, the user is configured by pairing the K-th receiver 230 and the K-th transmitter 210 as shown in FIG. 2. Each of the first to K th receivers 230 transmits information to the first to K th transmitters 210 as shown in FIG. 2. Hereinafter, the first to K th receivers 230 will be collectively referred to as a receiver, and the first to K th transmitters 210 will be collectively referred to as a transmitter.

In detail, the power calculator 110 calculates the slope of the weighted sum rate and the slope of the virtual signal to interference and noise ratio to maximize the weighted sum rate and the virtual signal to interference and noise ratio for the user. The power calculator 110 calculates interference and noise power and desired signal power in the receiver based on the slope of the weighted sum transmission rate and the slope of the virtual signal to interference and noise ratio to maximize the virtual signal to interference and noise ratio. The power calculating unit 110 calculates the diagonal matrix in the receiver using the calculated interference and noise power and the desired signal power in the receiver. The power calculator 110 provides the calculated diagonal matrix to the coefficient calculator 120.

The coefficient calculator 120 calculates a plurality of weighting coefficients using a diagonal matrix. In other words, the coefficient calculating unit 120 first initializes the weighting coefficient. The coefficient calculator 120 receives the diagonal matrix of the receiver from the power calculator 110. The coefficient calculating unit 120 calculates a plurality of weighting coefficients by using a diagonal matrix and a vector of all elements of the receiver provided from the power calculating unit 110. That is, the coefficient calculating unit 120 updates the initialized weighting coefficients with a plurality of weighting coefficients calculated based on the diagonal matrix of the receiver and the vector of all elements 1. The coefficient calculator 120 provides the calculated weighting coefficients to the beamforming calculator 130.

The beamforming calculator 130 calculates a beamforming vector of the transmitter based on the plurality of weighting coefficients. That is, the beamforming calculator 130 receives a plurality of weighting coefficients from the coefficient calculator 120. The beamforming operator 130 extracts at least one weighting factor that maximizes the virtual signal-to-interference and noise ratio from the plurality of weighting coefficients. The beamforming operation unit 130 calculates the beamforming vector of the transmitter using the extracted at least one weighting system and channel vectors of the receiver and the transmitter.

The display unit 140 is a means for displaying the operation information and the result information generated during the operation of the beamforming design apparatus 100 for the administrator to check. For example, the display unit 140 may display a process of calculating the interference and noise power, the desired signal power, and the diagonal matrix in the receiver by the power calculator 110, and in the receiver calculated by the power calculator 110. The interference and noise power, the desired signal power, and the diagonal matrix can be displayed. The display unit 140 may display a process of calculating a plurality of weighting coefficients in the coefficient calculating unit 120, and may display a plurality of weighting coefficients calculated through the coefficient calculating unit 120. In addition, the display unit 140 may display a process of calculating the beamforming vector through the beamforming operation unit 130, and may display a beamforming vector calculated by the beamforming operation unit 130.

If the display unit 140 is a device capable of displaying the beamforming vector calculated by the beamforming operation unit 130, the type thereof is irrelevant. For example, the display unit 140 may be one of a liquid crystal display (LCD), an organic light emitting display (OLED), and an electrophoretic display (EPD).

The storage unit 150 stores various programs for controlling the overall operation of the beamforming design apparatus 100. The storage unit 150 stores various data generated by program execution and acquired data. For example, the storage unit 150 may store the interference and noise power, the desired signal power, and the diagonal matrix in the receiver calculated by the power calculator 110. The storage unit 150 may store a plurality of weighting coefficients calculated by the coefficient calculating unit 120, and may store the beamforming vector calculated by the beamforming operation unit 130.

Meanwhile, the storage 150 may provide necessary data at the request of the power calculator 110, the coefficient calculator 120, the beamforming calculator 130, and the display 140. The storage unit 150 may be formed of an integrated memory or may be divided into a plurality of memories. For example, the storage unit 150 may include a read only memory (ROM), a random access memory (RAM), a flash memory, and the like.

3 is a flowchart illustrating a beamforming design method according to an embodiment of the present invention.

On the other hand, the configuration of the beamforming design apparatus 100 according to an embodiment of the present invention described with reference to FIG. 1 can be integrated or subdivided, regardless of the name, the component that performs the above-described function is It will be apparent that the configuration of the beamforming design apparatus 100 according to an embodiment of the present invention may be achieved. Therefore, hereinafter, in describing the beamforming design method according to the present invention, the main body of each step will be described based on the beamforming design apparatus 100 instead of the corresponding component.

로 각각 표시한다. 항등 행렬은 I로 표시한다. 모든 N-차원 열 벡터들의 집합은 C^N으로 주어진다.In the following, transpose, Hermitian transpose, Euclidean 2-norm operators are defined as (·) ^T , (·) ^H and

Mark each as The identity matrix is denoted by I. The set of all N-dimensional column vectors is given by C ^N.

Referring to FIG. 3, the beamforming design apparatus 100 calculates interference and noise power, desired signal power, and diagonal matrix in a receiver using a weighted sum rate and a virtual signal to interference and noise ratio for a user (310). . First, the transmitter 210 is equipped with M antennas 215 as shown in FIG. Each of the transmitter 210 and the receiver 230 has K pieces as shown in FIG. 4. In an embodiment of the present invention, it is assumed that M ≧ K. In this case, the received signal at the receiver 230 may be defined as shown in [Equation 1].

[Equation 1]

는 수신기에서의 수신 신호,

는 송신기j와 수신기k의 채널 벡터,

는 수신기에서의 부가 백색 가우스 잡음(additive complex Gaussian noise vector),

는 수신기에 예정된 데이터 심볼,

는 송신기에서의 빔포밍 벡터를 나타낸다. 이때, 빔포밍 벡터(

)는 송신기의 전력 제한을 충족시키기 위해 [수학식 2]를 조건으로 한다.
here,

Is the received signal at the receiver,

Is the channel vector of transmitter j and receiver k,

Is the additive white Gaussian noise vector at the receiver,

Is the data symbol scheduled for the receiver,

Denotes a beamforming vector at the transmitter. In this case, the beamforming vector (

) Is subject to Equation 2 to meet the power limitation of the transmitter.

&Quot; (2) "

는 송신기에서의 빔포밍 벡터를 나타낸다.here,

Denotes a beamforming vector at the transmitter.

Under the assumption of single user detection (SUD), an individual transmission rate of a user may be defined through Equation 3.

&Quot; (3) "

는 사용자의 개별 전송률을 나타낸다. 그리고,

은 개별 신호 대 간섭 및 잡음비(Signal-to-Interference and Noise Ratio: 이하, SINR로 통칭함)을 나타내며, [수학식 4]와 같이 정의한다.
here,

Represents the individual transmission rate of the user. And,

Denotes an individual signal-to-interference and noise ratio (hereinafter referred to as SINR), and is defined as shown in [Equation 4].

&Quot; (4) "

은 개별 SINR을 나타낸다. here,

Represents an individual SINR.

In order to maximize SINR and weighted sum rate, it may be defined as shown in [Equation 5].

[Equation 5]

는 사용자의 개별 전송률이다. 상기 [수학식 5]는 비볼록성(non-convexity)으로 인해 복잡하다. 최적의 가중 합 전송률은 성취 가능한 전송률 영역의 파레토(Pareto) 경계에서 일어나므로, 전송률 영역과 파레토 경계의 구체적인 정의를 다음과 같이 나타낸다.here,

Is the individual baud rate of the user. Equation 5 is complicated by non-convexity. Since the optimal weighted sum rate occurs at the Pareto boundary of the attainable rate region, a concrete definition of the rate region and Pareto boundary is shown as follows.

Definition 1, the achievable data rate for channel implementation is defined as [Equation 6].

&Quot; (6) "

는 채널 구현에 대한 성취 가능한 전송률,

는 사용자의 개별 전송률을 나타낸다.here,

Is the attainable bit rate for the channel implementation,

Represents the individual transmission rate of the user.

Definition 2 The Pareto boundary is composed of Pareto optimal points, called Pareto optimals, which are referred to as Pareto optimals, in the absence of other rate tuples. Pareto boundaries are defined as shown in Equation 7.

[Equation 7]

은 전송률 튜플이며,

는 다른 전송률 튜플을 나타낸다.

는 원소별 부등식을 나타낸다.here,

Is the rate tuple,

Denotes a different rate tuple.

Denotes an inequality by element.

)의 외부 경계임을 확인할 수 있다. 즉, 가중 합 전송률의 최대화를 위한 파레토 최적 점들만 고려할 수 있다.In the beamforming design apparatus 100, the Pareto boundary is defined as a data rate region through Definitions 1 and 2.

You can see that it is the outer boundary of). That is, only Pareto optimal points for maximizing the weighted sum rate may be considered.

)이 K개의 선형 독립 벡터들로 구성되는 것을 가정하면, 모든 송신기들에서 최대 전력 전송이며, 최적성의 어떠한 손실도 없는 [수학식 8]과 같이 정의할 수 있다. 이에 따라, 빔포밍 설계 장치(100)는 전력 제어를 적용할 필요가 없다.
Beamforming design device 100 is M ≥ K, the set (

A) consists of K linear independent vectors, which is the maximum power transmission in all transmitters and can be defined as Equation 8 without any loss of optimality. Accordingly, the beamforming design apparatus 100 does not need to apply power control.

[Equation 8]

는 송신기에서의 빔포밍 벡터를 나타낸다.here,

Denotes a beamforming vector at the transmitter.

The beamforming design apparatus 100 defines a virtual signal-to-interference and noise ratio (hereinafter, collectively referred to as VSINR) for a user as shown in [Equation 9].

&Quot; (9) "

는 사용자에 대한 VSINR,

는 가중 계수를 나타낸다. 이때, j와 k는 서로 같지 않다. 가중 계수를 적절히 선택하는 조건하에 VSINR을 최대화하는 빔포밍 벡터는 [수학식 10]과 같이 정의한다.
here,

Is the VSINR for the user,

Denotes the weighting factor. At this time, j and k are not equal to each other. The beamforming vector maximizing VSINR under the condition of properly selecting the weighting coefficient is defined as shown in [Equation 10].

&Quot; (10) "

는 송신기k의 빔포밍 벡터,

는 가중 계수,

는 송신기j와 수신기k의 채널 벡터를 나타낸다.here,

Is the beamforming vector of transmitter k,

Is a weighting factor,

Denotes the channel vector of the transmitter j and the receiver k.

The beamforming design apparatus 100 calculates the weighted sum rate and the slope of each VSINR to maximize the weighted sum rate. The weighted sum rate and the slope of each VSINR are defined as shown in [Equation 11].

&Quot; (11) "

는 가중 합 전송률의 기울기,

는 가중치,

는 VSINR의 기울기를 나타낸다. 그리고,

는 수신기에서의 신호 및 잡음 전력을 나타내며, [수학식 12]와 같이 정의할 수 있다.

는 수신기에서의 희망 신호 전력을 나타내고, [수학식 13]과 같이 정의할 수 있다.
here,

Is the slope of the weighted sum rate,

Is the weight,

Represents the slope of VSINR. And,

Denotes the signal and noise power at the receiver, and can be defined as shown in Equation 12.

Represents the desired signal power at the receiver, and may be defined as in Equation 13.

[Equation 12]

는 수신기에서의 신호 및 잡음 전력,

는 송신기j와 수신기k의 채널 벡터를 나타낸다. 따라서, 빔포밍 설계 장치(100)는 [수학식 12]를 이용하여 수신기에서의 신호 및 잡음 전력을 연산할 수 있다.
here,

Is the signal and noise power at the receiver,

Denotes the channel vector of the transmitter j and the receiver k. Therefore, the beamforming design apparatus 100 may calculate signal and noise power at the receiver by using Equation 12.

&Quot; (13) "

는 수신기에서의 희망 신호 전력을 나타내며,

는 송신기에서의 빔포밍 벡터를 나타낸다. 즉, 빔포밍 설계 장치(100)는 [수학식 13]을 이용하여 수신기에서의 희망 신호 전력을 연산할 수 있다.here,

Represents the desired signal power at the receiver,

Denotes a beamforming vector at the transmitter. That is, the beamforming design apparatus 100 may calculate the desired signal power at the receiver by using Equation 13.

The beamforming design apparatus 100 calculates a diagonal matrix at the receiver by using interference, noise power, and desired signal power at the receiver (320). In detail, the beamforming design apparatus 100 may confirm that the slope of the weighted sum transmission rate and the slope of the VSINR become zero at the same point in [Equation 11]. Here, the slope of 0 means that each cost function has reached a stationary point, which can be thought of as a local optimal point, so the slope is equal to two equations. To calculate the weighting factor.

The beamforming design apparatus 100 may be defined as shown in [Equation 14] when k and l are not equal.

&Quot; (14) "

)에 대한 선형 방정식으로 [수학식 15]로 변환할 수 있다. 이때, k와 l은 같지 않다.
The beamforming design apparatus 100 calculates the weighting coefficient (Equation 14).

) Can be converted into Equation 15. K and l are not equal.

&Quot; (15) "

에 걸쳐 방정식들을 조합하면, [수학식 16]과 같은 간결한 행렬식을 획득할 수 있다.
Beamforming design device 100 is all

By combining the equations over, we can obtain a concise determinant such as [Equation 16].

&Quot; (16) "

는 대각 행렬을 나타내며,

는 계수 전치 행렬을 나타낸다.

및

는 [수학식 17]과 같이 정의할 수 있다.
Where 1 _K-1 is a vector of length K-1 in which all elements are 1,

Represents the diagonal matrix,

Denotes the coefficient transpose matrix.

And

Can be defined as shown in [Equation 17].

&Quot; (17) "

는 대각 행렬,

는 수신기에서의 희망 신호 전력,

는 수신기에서의 신호 및 잡음 전력을 나타낸다. 그리고,

는 계수 전치 행렬을 나타낸다. 즉, 빔포밍 설계 장치(100)는 [수학식 17]에 수신기에서의 희망 전력(

) 및 수신기에서의 신호 및 잡음 전력(

)을 대입하여 대각 행렬(

)을 연산한다.here,

Is a diagonal matrix,

Is the desired signal power at the receiver,

Denotes the signal and noise power at the receiver. And,

Denotes the coefficient transpose matrix. That is, the beamforming design apparatus 100 expresses the desired power at the receiver in [Equation 17].

) And signal and noise power at the receiver (

) To substitute for the diagonal matrix (

).

The beamforming design apparatus 100 calculates a plurality of weighting coefficients using a diagonal matrix (330). In other words, the beamforming design apparatus 100 converts the equation as shown in Equation 18 to calculate a plurality of weighting coefficients in Equation 16.

&Quot; (18) "

는 계수 전치 행렬,

는 대각 행렬, 1_K-1은 모든 원소가 1인 길이 K-1의 벡터를 나타낸다. 빔포밍 설계 장치(100)는 [수학식 18]에 대각 행렬(

) 및 모든 원소가 1인 길이 K-1의 벡터를 대입하여 계수 전치 행렬을 연산할 수 있다. 그리고, 빔포밍 설계 장치(100)는 계수 전치 행렬을 기반으로 복수의 가중 계수(

)를 연산한다.here,

Is the coefficient transpose,

Is a diagonal matrix, and 1 _K-1 represents a vector of length K-1 in which all elements are one. The beamforming design apparatus 100 uses a diagonal matrix (Equation 18).

) And a coefficient transpose matrix can be calculated by substituting a vector of length K-1 having all elements 1. In addition, the beamforming design apparatus 100 uses a plurality of weighting coefficients based on the coefficient transpose matrix.

) Is calculated.

The beamforming design apparatus 100 calculates a beamforming vector of a transmitter using a plurality of weighting coefficients (340). In other words, the beamforming design apparatus 100 extracts at least one weighting factor maximizing VSINR from a plurality of weighting coefficients, and uses the at least one weighting factor extracted based on Equation 10 to transmit the beamforming of the transmitter. Calculate a vector Meanwhile, the beamforming design apparatus 100 may repeat steps 310 to 340 until convergence.

를 의미한다. 이때, k=1, ......, K이다.5 is a flowchart illustrating a beamforming design method according to another embodiment of the present invention. Referring to FIG. 5, the beamforming design apparatus 100 calculates a slope of a beamforming vector of a transmitter (510). Specifically, the beamforming design method of FIG. 5 will be described with an example of a distributed beamforming technique that operates only with local channel state information (hereinafter, referred to as CSI). In this case, the local CSI is applied to the channel vectors connected to the transmitter l.

. At this time, k = 1, ..., K.

만을 사용하여 송신기의 빔포밍 벡터(

)의 연산을 가능하게 하기 위해 높은 SINR 및 신호 대 잡음(Signal-to-Noise Ratio: 이하, SNR로 통칭함)의 근사식들을 적용하여 [수학식 5]에서 가중 합 전송률을 K개 별개의 문제들로 분리한다. 특히, 빔포밍 설계 장치(100)는 사용자가 2일 경우(K=2)에는 높은 SNR 근사식을 유도할 수 있다.Beamforming design device 100

Using only the beamforming vector of the transmitter (

In order to enable the calculation of the equations, we apply approximations of high SINR and signal-to-noise ratio (hereinafter referred to as SNR) to determine the weighted sum rate in Equation 5. To separate them. In particular, the beamforming design apparatus 100 may induce a high SNR approximation equation when the user is 2 (K = 2).

The beamforming design apparatus 100 applies a high SINR approximation to Equation 19.

&Quot; (19) "

)에만 종속하는 항들을 모으면 [수학식 20]과 같이 정의할 수 있다.
The beamforming design apparatus 100 uses the beamforming vector of the transmitter in Equation (19).

If you collect terms that depend only on), you can define them as shown in Equation 20.

&Quot; (20) "

이기 때문에, 사용자가 2일 경우에 있어서는

이 송신기의 빔포밍 벡터(

)에만 종속한다는 것을 확인할 수 있다. 빔포밍 설계 장치(100)는

의 일반 구성들에 대한 분리된 문제들을 얻기 위해 또 다른 근사식을 적용한다. 높은 SNR에서는 성능 감소가 주로 사용자 간 간섭으로부터 나오기 때문에 제로 포싱(Zero-Forcing: ZF) 빔포밍이 최적에 가까운 가중 합 전송률 성능을 보인다는 것에 주의해야 한다. 따라서, 빔포밍 설계 장치(100)는 최적의 가중 합 전송률 성능을 얻기 위해서 항들(

)이 매우 작아야 한다. 그러므로, 빔포밍 설계 장치(100)는

을 송신기의 빔포밍 벡터(

) 및 CSI들이

에만 종속하는 [수학식 21]의 근사식으로 정의할 수 있다.
When the beamforming design device 100 is K = 2

Therefore, when the user is 2

The beamforming vector of this transmitter (

You can see that it depends only on Beamforming design device 100

Apply another approximation to get separate problems for the general components of It should be noted that at high SNR, zero-forcing (ZF) beamforming yields near-optimal weighted sum-rate performance because performance reduction is primarily due to user-to-user interference. Accordingly, the beamforming design apparatus 100 may determine terms (i.e., in order to obtain an optimal weighted sum rate performance).

Should be very small. Therefore, the beamforming design apparatus 100

The beamforming vector of the transmitter

) And CSI

It can be defined as an approximation of [Equation 21], which depends only on.

&Quot; (21) "

)을 [수학식 22]의 것에 대한 해로서 연산할 수 있다.
As a result, the beamforming design apparatus 100 may determine that the transmitter 1 uses only the local CSI.

) Can be calculated as a solution to [Equation 22].

&Quot; (22) "

의 기울기를 [수학식 23]과 같이 정의할 수 있다.
The beamforming design apparatus 100 may employ the VSINR approach to calculate Equation 22. Beamforming design device 100

The slope of can be defined as [Equation 23].

&Quot; (23) "

는

의 기울기를 나타낸다. 즉, 빔포밍 설계 장치(100)는 [수학식 23]을 이용하여

의 기울기를 연산할 수 있다.here,

The

Indicates the slope of. That is, the beamforming design apparatus 100 may use Equation 23.

The slope of can be calculated.

와 VISNR 사이에 연계를 이루기 때문에 [수학식 23] 및 [수학식 11]에서 VSINR의 기울기(

)이 [수학식 24]의 조건일 경우에 동일한 점에서 0이 된다는 것을 판단할 수 있다.
The beamforming design apparatus 100 calculates a distributed diagonal matrix (520). In other words, the beamforming design apparatus 100

Because of the association between and VISNR, the slope of VSINR in Equations 23 and 11

) Can be determined to be 0 at the same point when the condition of Equation (24).

&Quot; (24) "

는 계수 전치 행렬을 나타낸다.

는 분산 대각 행렬을 나타내며, [수학식 25]와 같이 정의할 수 있다.
Where 1 _K-1 is a vector of length K-1 in which all elements are 1,

Denotes the coefficient transpose matrix.

Represents a variance diagonal matrix and can be defined as shown in Equation 25.

&Quot; (25) "

)을 연산할 수 있다.That is, the beamforming design apparatus 100 uses a distributed diagonal matrix (Equation 25).

) Can be calculated.

The beamforming design apparatus 100 calculates a plurality of weighting coefficients using the distributed diagonal matrix (530). In other words, the beamforming design apparatus 100 converts the equation as shown in Equation 25 to calculate a plurality of weighting coefficients in Equation 24.

&Quot; (25) "

는 계수 전치 행렬,

는 분산 대각 행렬, 1_K-1은 모든 원소가 1인 길이 K-1의 벡터를 나타낸다. 빔포밍 설계 장치(100)는 [수학식 18]에 분산 대각 행렬(

) 및 모든 원소가 1인 길이 K-1의 벡터를 대입하여 계수 전치 행렬을 연산할 수 있다. 그리고, 빔포밍 설계 장치(100)는 계수 전치 행렬을 기반으로 복수의 가중 계수를 연산한다.here,

Is the coefficient transpose,

Is a distributed diagonal matrix, and 1 _K-1 represents a vector of length K-1 in which all elements are 1. The beamforming design apparatus 100 uses a distributed diagonal matrix (Equation 18).

) And a coefficient transpose matrix can be calculated by substituting a vector of length K-1 having all elements 1. The beamforming design apparatus 100 calculates a plurality of weighting coefficients based on the coefficient transpose matrix.

The beamforming design apparatus 100 calculates a beamforming vector of a transmitter using a plurality of weighting coefficients (540).

6 to 8 are graphs showing simulation results by applying a beamforming design method according to an embodiment of the present invention.

First, suppose spatially uncorrelated rayleigh fading channels with unit variance in all simulations.

Reference numeral 610 shown in FIGS. 6 to 8 denotes a technique using Maximum-Ratio Transmission (MRT). The technique using maximum non-transmission maximizes its channel gain by ignoring interference.

Reference numeral 620 denotes a technique using zero-forcing (ZF). The technique using zero forcing is a technique for optimizing beamformers while removing interference to other users.

)을 이용하여 VISNR을 최대화하는 기술이다.Reference numeral 630 denotes a technique using VSINR. The technique using VSINR is based on the unweighted coefficient (

) To maximize VISNR.

Reference numeral 640 denotes a technique using an exhaustive search. The technique using the global search is a technique to perform the global search to maximize the weighted sum rate using the parameterization.

Reference numeral 650 denotes a technique using maximization of the VSINR and weighted sum rate according to an embodiment of the present invention.

Reference numeral 660 denotes a technology using CSI according to another embodiment of the present invention.

6 shows [w1, w2] = [3, 1] for interference channels (IC) of a multiple input single output (MIS) having an antenna M of 2 and a user of 2. FIG. The sum of the weighted sum data rates for. Referring to FIG. 6, the proposed schemes start with only one initial point, but the proposed centralized scheme 650 exhibits near optimal performance, and the proposed distributed scheme 660 provides almost the same performance as the centralized scheme. You can check it.

FIG. 7 shows the sum of the weighted sum transmission rates for [w1, w2] = [5, 1] in the interference channel of the multi-input single output of which the antenna M is 2 and the user is 2. FIG. Referring to FIG. 7, it can be seen that as the ratio of maximum (w1, w2) / minimum (w1, w2) increases, the proposed centralized and distributed methods increase.

FIG. 8 shows the sum of weighted sum transmission rates for [w1, w2, w3] = [10, 5, 1] for an interference channel of a multi-input single output with 3 antennas M and 3 users. Referring to FIG. 8, it is difficult to implement a global search method because global search for K (K-1) = 6 real variables and K ² = 9 complex variables for parameterization must be performed, respectively. However, the distributed scheme proposed in the present invention can obtain a performance gain of about 6 dB compared to the VSINR maximized scheme 630 without any additional CSI exchange overhead.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art to which the present invention pertains without departing from the spirit and scope of the present invention as set forth in the claims below It will be appreciated that modifications and variations can be made.

Claims (6)

An apparatus for designing beamforming at multiple input single output,
A power calculation unit for calculating interference and noise power, desired signal power, and diagonal matrix in the receiver using a weighted sum rate and a virtual signal-to-interference and noise ratio for a pair of transmitters and receivers;
A coefficient calculator for calculating a plurality of weighting coefficients using the diagonal matrix calculated by the power calculator; And
And a beamforming calculator configured to calculate a beamforming vector of the transmitter using the plurality of weighting coefficients calculated by the coefficient calculator.
The method according to claim 1,
The power calculation unit,
Calculate the slope of the weighted sum rate and the slope of the virtual signal to interference and noise ratio to maximize the weighted sum rate and the virtual signal to interference and noise ratio, Calculates the interference and noise power and the desired signal power at the receiver based on the slope, and calculates the diagonal matrix at the receiver using the interference and noise power and the desired signal power at the receiver. Beamforming design device at a single output.
The method according to claim 1,
The beamforming calculation unit,
Extracting at least one weighting factor that maximizes the virtual signal-to-interference and noise ratio from the plurality of weighting factors, and using the extracted at least one weighting factor and channel vectors of the receiver and the transmitter to form a beamforming vector of the transmitter Beamforming design apparatus for a multi-input single output, characterized in that for calculating.
In the beamforming design apparatus for designing beamforming in a multi-input single output,
Calculating interference and noise power, desired signal power, and diagonal matrix in the receiver using a weighted sum rate and a virtual signal-to-interference and noise ratio for a pair of transmitters and receivers;
Calculating a plurality of weighting coefficients using the calculated diagonal matrix; And
And calculating a beamforming vector of the transmitter using the calculated plurality of weighting coefficients.
5. The method of claim 4,
Computing the interference and noise power, the desired signal power, the diagonal matrix in the receiver,
Calculating a slope of the weighted sum rate and a slope of the virtual signal to interference and noise ratio to maximize the weighted sum rate and the virtual signal to interference and noise ratio;
Calculating interference and noise power and desired signal power at the receiver based on the slope of the weighted sum rate and the slope of the virtual signal to interference and noise ratio; And
And calculating a diagonal matrix at the receiver using interference, noise power, and desired signal power at the receiver.
5. The method of claim 4,
Computing the beamforming vector of the transmitter,
Extracting at least one weighting factor from the plurality of weighting factors to maximize the virtual signal to interference and noise ratio; And
And calculating a beamforming vector of the transmitter by using the extracted at least one weighting factor and channel vectors of the receiver and the transmitter.

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