KR20200001397A - Basement apparatus, and control method thereof - Google Patents

Abstract

The present invention relates to a terminal (user) selection technique for increasing a performance rate (sum rate) of simultaneous data transmission in a multi-user multiple-input multiple-output (MU-MIMO) downlink environment.

Description

Base station apparatus and operation method of base station apparatus {BASEMENT APPARATUS, AND CONTROL METHOD THEREOF}

The present invention relates to a terminal (user) selection technique for improving the performance rate (sum rate) of simultaneous data transmission in a multi-user multiple-input multiple-output (MU-MIMO) downlink environment.

In order to increase transmission efficiency of data between a base station apparatus and a terminal in a wireless communication network, a multiple input multiple output (hereinafter referred to as MIMO) technology may be used.

MIMO technology refers to an antenna system capable of multiple inputs and outputs, and can increase network capacity by using a plurality of antennas of a base station apparatus and a terminal, and according to a data transmission / reception method, a single user MIMO (hereinafter referred to as SU-MIMO) The method may be classified into a multi-user MIMO (hereinafter referred to as MU-MIMO) scheme.

In particular, MU-MIMO is a technology that expects higher channel capacity than SU-MIMO through multiuser gain and spatial diversity. To get the maximum sum rate, MU-MIMO receives data among many users in a cell at the same time. The most important thing is how to select a terminal (user) group.

In this regard, conventional terminal (user) selection techniques sequentially select terminals for simultaneous data transmission, and in this terminal selection process, only one first terminal is selected.

However, in this case, if the first terminal is not included in the optimal terminal group (set), error propagation that does not always have an optimal value also based on the subsequent terminal is sequentially selected based on the first terminal (error propagation) can cause problems.

Accordingly, the present invention is to propose a new technique that can minimize the problem of error propagation of the existing terminal selection technology in the MU-MIMO environment.

The present invention has been made in view of the above circumstances, and an object of the present invention is to select a new terminal (user) that can improve the performance rate (sum rate) of simultaneous data transmission in a MU-MIMO downlink environment. To propose a technique.

A base station apparatus according to an embodiment of the present invention for achieving the above object, the generation unit for generating a reference terminal group by selecting one or more reference terminals based on the channel information of each of the plurality of terminals; A configuration unit configured to select at least one terminal capable of simultaneously transmitting data with the reference terminal in the reference terminal group and configure a subgroup for each reference terminal in the reference terminal group; And a determination unit which determines, as a simultaneous transmission group, a subgroup in which a performance index according to simultaneous data transmission is maximum among the subgroups for each reference terminal.

In detail, the channel information is represented by a channel matrix relating to a channel between the antenna of the base station apparatus and the antenna of the terminal in relation to the downlink channel between the base station apparatus and the terminal, and the generation unit includes the order of the channel matrix. A terminal group having a determinant value of a correlation matrix based on a) may be selected as a reference terminal.

Specifically, the configuration unit may select each reference terminal in the reference terminal group as the first terminal in the subgroup.

In detail, the configuration unit may sequentially select terminals having channel information orthogonal to each previously selected terminal after selecting the first reference terminal for each subgroup.

Specifically, the configuration unit, if the terminal having the channel information orthogonal to each terminal previously selected after the reference terminal for each subgroup is first selected, the terminal having the highest determinant value among the two or more terminals You can configure subgroups by selecting.

Specifically, the performance indicator is the total sum of data reception performances predicted for each terminal when the base station apparatus simultaneously transmits data of each terminal for each subgroup through block diagonal precoding. Can be defined.

In accordance with an aspect of the present invention, there is provided a method of operating a base station apparatus, including: a reference terminal group generation step of selecting one or more reference terminals based on channel information of each of a plurality of terminals to generate a reference terminal group; A subgroup configuration step of configuring a subgroup by selecting at least one terminal capable of simultaneously transmitting data with the reference terminal in the reference terminal group for each reference terminal in the reference terminal group; And a simultaneous transmission group determining step of determining, as a simultaneous transmission group, a subgroup in which a performance index according to simultaneous data transmission is maximum among the subgroups for each reference terminal.

Specifically, the channel information is represented by a channel matrix relating to a channel between the antenna of the base station apparatus and the antenna of the terminal in relation to the downlink channel between the base station apparatus and the terminal, wherein the reference terminal group generation step is the channel matrix. A reference terminal group may be generated by selecting, as a reference terminal, a terminal whose determinant value of a correlation matrix based on a dimension of a value greater than or equal to a threshold value.

Specifically, in the subgroup configuring step, each reference terminal in the reference terminal group may be selected as the first terminal in the subgroup.

Specifically, in the subgroup configuring step, after selecting the first reference terminal for each subgroup, the terminal having channel information orthogonal to each previously selected terminal may be sequentially selected.

Specifically, in the subgroup configuring step, when the reference terminal for each subgroup is first selected and there are two or more terminals having channel information orthogonal to each previously selected terminal, the determinant value of the two or more terminals is increased. The largest terminal can be selected to form a subgroup.

Specifically, the performance indicator is the total sum of data reception performances predicted for each terminal when the base station apparatus simultaneously transmits data of each terminal for each subgroup through block diagonal precoding. Can be defined.

According to an operation method of a base station apparatus and a base station apparatus of the present invention, in selecting a user (terminal) for simultaneous data transmission in a MU-MIMO downlink environment, a primary terminal group satisfying a specific criterion when selecting a first terminal (primary user) By selecting a group, a problem of error propagation that can occur when only a single terminal is selected can be minimized, thereby improving the performance rate of the data simultaneous transmission.

1 is an exemplary view showing a wireless communication network according to an embodiment of the present invention.
2 is an exemplary diagram of a MU-MIMO downlink system model considered in an embodiment of the present invention.
3 is a block diagram showing the configuration of a base station apparatus according to an embodiment of the present invention.
4 is an exemplary view for explaining a terminal selection process according to an embodiment of the present invention.
5 is a flowchart illustrating a method of operating a base station apparatus according to an embodiment of the present invention.

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

1 is an exemplary view showing a wireless communication network according to an embodiment of the present invention.

As shown in FIG. 1, a wireless communication network according to an embodiment of the present invention includes a base station apparatus 10 and a plurality of terminals 20 that receive downlink data from the base station apparatus 10.

The base station apparatus 10 adopts a multiple input multiple output (hereinafter referred to as MIMO) technology in order to increase data transmission efficiency. In particular, the base station apparatus 10 adopts the MU- to expect high channel capacity through multiuser gain and spatial diversity. Follow MIMO technology.

Accordingly, the base station apparatus 10 may simultaneously transmit data to the plurality of terminals 20 using the same time and the same frequency resource according to the application of the MU-MIMO technology.

However, since the total number of antennas of the base station apparatus 10 cannot be larger than the total number of antennas of the terminal receiving data, the number of terminals that can simultaneously transmit data in the base station apparatus 10 is limited.

As a result, a problem of terminal selection regarding how to select a subgroup of a terminal receiving data simultaneously among many terminals, which is a core issue of MU-MIMO technology, occurs.

In this regard, as an optimal terminal selection method, that is, a terminal selection method having a maximum performance rate, a full search (FS) considering the total number of terminals and the number of all cases made by the number of terminals that can be selected ) Method exists.

However, this FS method is accompanied with the problem that the complexity (complexity) for calculating the optimal terminal group increases exponentially as the number of terminals that can be selected increases.

In order to solve this problem, various user selection techniques have been developed in consideration of a trade-off between a performance rate and a complexity.

In this regard, conventional terminal (user) selection techniques sequentially select terminals for simultaneous data transmission, and follow the method of selecting only one terminal in the terminal selection process.

However, in this case, if the previous terminal is erroneously selected when the terminals are sequentially selected, that is, if the user is not included in the optimal terminal group, the selection of the next terminal may not be included in the optimal terminal group.

In other words, if the first terminal is not included in the optimal terminal group (set), the performance rate (sum rate) based on the terminal after being sequentially selected based on the first terminal also does not always have an optimal value propagation error ( error propagation).

Accordingly, one embodiment of the present invention is to propose a new technology that can improve the performance indicator (sum rate) of data simultaneous transmission by minimizing the problems of the conventional terminal selection technology.

와

는 각각 행렬의 transpose와 conjugate transpose를 나타내며,

,

그리고

은 각각 행렬의 expectation, trace 그리고 determinant를 나타내며,

는 정방 행렬의 identity matrix를 나타내며, 마지막으로,

은 집합의 크기를 나타낸다.Meanwhile, bold and lowercase bold described below mean a matrix and a vector, respectively.

Wow

Denotes the transpose and conjugate transpose of the matrix, respectively.

,

And

Represents the expectation, trace and determinant of the matrix, respectively

Represents the identity matrix of the square matrix. Finally,

Represents the size of the set.

In addition, in the case of a performance rate (sum rate) of simultaneous data transmission according to an embodiment of the present invention, it may be derived through a process of decoding a received signal of a terminal.

Figure 2 shows an exemplary diagram of the MU-MIMO downlink system model considered in an embodiment of the present invention.

개의 단말 가운데 적절한 단말 선택 알고리즘(user selection algorithm)에 의해

명의 사용자가 선택되며, 선택된

명의 사용자에 대한 데이터는 블록 대각화 프리코딩(Block Diagonalization Precoding)을 거쳐

개의 기지국 안테나를 통해 전송된다.As shown in FIG. 2, the data that can be transmitted simultaneously by the base station apparatus 10 has a limit.

By appropriate user selection algorithm among the two terminals

Users selected,

Data for two users is subject to Block Diagonalization Precoding

Are transmitted through the base station antennas.

는

명의 선택된 사용자들 가운데

-th 사용자의 안테나 개수를 뜻하고,

는 기지국과

-th 사용자 사이의 채널을 뜻하며, 이때,

이고,

는

의 차수(dimension)을 갖는 채널행렬로, 이러한 채널행렬의 각 요소(element)는 a random variable of complex-valued zero-mean unit-variance Gaussian distribution이며,

는 기지국장치(10)에서

-th 단말을 위해 생성한 데이터로,

를 만족한다.here,

Is

Of selected users

-th means the number of antennas of the user,

With the base station

-th means channel between users,

ego,

Is

A channel matrix with a dimension of, where each element of the channel matrix is a random variable of complex-valued zero-mean unit-variance Gaussian distribution

In the base station apparatus 10

-th generated data for the terminal,

Satisfies.

개의 단말 중 임의의 단말의 수신신호를 살펴보고, 수신신호를 디코딩하는 과정을 통해서 성능지표(sum rate)의 계산식을 다음과 같이 유도해볼 수 있다.Based on this

By looking at the received signal of any of the terminals of the terminal, and through the process of decoding the received signal can be derived the formula of the (sum rate) as follows.

-th 사용자의 수신신호 벡터

는 아래 [수식 1]과 같다.In the system model of Figure 2

-th user's received signal vector

Is shown in Equation 1 below.

[Equation 1]

-th 단말에게 전송될 desired signal part로, 기지국장치(10)에서

-th 단말로 보내려는 데이터

가 precoder

에 적용되어 채널

를 통해

-th 단말에게 수신된다.Where the first term on the right is

-th as the desired signal part to be transmitted to the terminal, the base station apparatus 10

-th Data to send to terminal

Autumn precoder

Applied to Channel

Through the

-th is received by the terminal.

-th 단말에게 수신되는 interference signal part로,

명의 선택된 단말 중

-th 단말 이외의 단말에게 전송하고자 하는 데이터로부터 야기되는 간섭신호이다.Also, the second term on the right side of the above formula

-th interference signal part received to the terminal,

Of selected terminals

-th Interference signal resulting from data to be transmitted to terminals other than the terminal.

는 Additive White Gaussian Noise (AWGN)로,

를 만족한다.And

Is Additive White Gaussian Noise (AWGN),

Satisfies.

는 BD를 사용하는데, BD는 단말들이 common resource를 share하면서 발생하는 co-channel interference를 완벽히 제거할 수 있으며, 아래 [수식 2]를 만족한다.Where precoder

Uses a BD, which can completely eliminate co-channel interference generated while the terminals share a common resource, and satisfies Equation 2 below.

[Formula 2]

개의 선택된 단말에 대한 성능지표(sum rate) 계산식은 다음과 같이 도출될 수 있다.As such, when the BD is used as the precoder in the base station apparatus 10,

The calculation formula of the sum rate for the selected terminals may be derived as follows.

를 아래 [수식 3]과 같이 정의한다.first,

Is defined as in [Equation 3] below.

[Equation 3]

는

의 null space에 포함되며,

의 null space를 구하기 위해서, 아래 [수식 4]에서와 같이

에 대해 Singular Value Decomposition (SVD)를 수행한다.Referring to [Equation 2] above,

Is

In the null space of the,

To find the null space of a, use Equation 4 below.

Perform Singular Value Decomposition (SVD) on.

[Equation 4]

의 각 column은

의 left-hand side singular vector이고, diagonal matrix

는

의 singular values를 포함한다.Where unitary matrix

Each column of

The left-hand side singular vector of the diagonal matrix

Is

Contains singular values.

의 각 row는

의 right-hand side singular vector이다. And unitary matrix

Each row in

Right-hand side singular vector

는

과

의 concatenation으로 표현되는데,

를

의 rank라고 할 때,

는

의 첫 번째 column 부터

번째 column 으로 구성된 행렬을 뜻하고,

는

의

번째 column 부터

번째 column 으로 구성된 행렬을 뜻한다.Also, in [Equation 4]

Is

and

Expressed as the concatenation of

To

When we say rank,

Is

From the first column of

Means the matrix of the second column,

Is

of

From the first column

The matrix consists of the first column.

는

의 null space의 orthogonal basis로 구성된다.

를 SVD 하면 아래 [수식 5]와 같이 나타낼 수 있다.At this time,

Is

It consists of an orthogonal basis of null space.

SVD can be expressed as [Equation 5] below.

[Equation 5]

는

로 정의 할 수 있고, 각 단말의 receive filter

는

로 정의 할 수 있다.Furthermore, BD precoder through [Equation 4] and [Equation 5]

Is

Defined by the receive filter of each terminal

Is

Can be defined as

는 아래 [수식 6]과 같이 나타낼 수 있다.At this time, decoded signal of each terminal

Can be expressed as in Equation 6 below.

[Equation 6]

명의 선택된 단말의 성능지표(sum rate)에 대한 계산식

은 [수식 6]을 통해 아래 [수식 7]과 같이 표현할 수 있다.Finally, in one embodiment of the present invention

Equation for sum rate of selected terminals

Equation 6 can be expressed as Equation 7 below.

[Formula 7]

Hereinafter, a terminal (user) selection technique capable of maximizing a performance index (sum rate) derived through the above-described process will be proposed.

Specifically, a base station apparatus 10 capable of maximizing a performance index (sum rate) is proposed.

In this regard, Figure 3 shows the configuration of a base station apparatus 10 according to an embodiment of the present invention.

As shown in FIG. 3, the base station apparatus 10 according to an embodiment of the present invention includes a generation unit 11 for generating a primary user group, a configuration unit 12 constituting a subgroup, And a determination unit 13 for determining a simultaneous transmission group.

In addition, the base station apparatus 10 according to an embodiment of the present invention may further include a configuration of a transmission unit 14 for simultaneously transmitting each data to the terminal determined the simultaneous transmission group.

The whole or at least part of the configuration of the base station apparatus 10 may be implemented in the form of a hardware module or a software module, or may be implemented in the form of a combination of a hardware module and a software module.

Here, the software module may be understood as, for example, an instruction executed by a processor controlling an operation in the base station apparatus 10, and the instruction may have a form mounted in a memory in the base station apparatus 10.

On the other hand, the base station apparatus 10 according to an embodiment of the present invention has a configuration in addition to the above-described configuration, further comprising a communication unit 15 which is an RF module that is responsible for the actual communication function with each terminal determined as a simultaneous transmission group. Can be.

Here, the communication unit 15 may include, but is not limited to, for example, an antenna system, an RF transceiver, one or more amplifiers, tuners, one or more oscillators, a digital signal processor, a codec chipset, a memory, and the like. Any known circuit to be performed may be included.

As a result, the base station apparatus 10 according to an embodiment of the present invention can realize a maximization of a performance index through the above-described configuration. Hereinafter, for each component in the base station apparatus 10 for realizing this, It will be described in more detail.

The generation unit 11 performs a function of generating a reference terminal group by selecting a reference terminal from a plurality of terminals.

Specifically, the generation unit 11 generates a reference terminal group by selecting a terminal satisfying a specific criterion among the plurality of terminals located in the coverage of the base station apparatus 10 as the reference terminal.

In this case, the generation unit 11 may select a reference terminal based on the channel information of each of the plurality of terminals, the channel information is related to the downlink channel between the base station apparatus and the terminal, between the antenna of the base station apparatus and the antenna of the terminal It can be expressed as a channel matrix for the channel of.

Here, the channel information is received from each of the plurality of terminals together with the eigen values of the correlation matrix based on the dimension of the channel matrix. In particular, the correlation matrix here is to be used as a specific condition for selecting a reference terminal. Can be.

In summary, when the channel information is received from the plurality of terminals, the generation unit 11 determines whether the determinant value of the correlation matrix based on the received channel information is greater than or equal to the threshold value, and the determination result determines that the determinant value is critical. The terminal that is greater than or equal to the value can be selected as the reference terminal belonging to the reference terminal group.

In other words, for example, as shown in (a) of FIG. 4, a specific condition in which the determinant value of the correlation matrix is greater than or equal to a threshold value among the entire terminals 1, 2, ..., K _T located in the coverage of the base station apparatus 10 is determined. At least some of the terminals Z ₁ , Z ₂ ,..., Z _{r that} are _satisfied may be selected to generate a reference terminal group as shown in FIG. 4 (b).

For better understanding of the description, the operation of the generation unit 11 for generating the reference terminal group will be described in more detail with reference to a formula.

,

) 및 상관행렬(

)의 고유값(eigen values;

,

)을 수신할 수 있으며, 이때의 기준단말을 선택을 위한 특정 기준은, 아래 [수식 8]과 같은 상관행렬(

)을 활용한 디터미넌트인

로 정의될 수 있다.First, channel information from each terminal (

,

) And correlation matrix (

Eigen values;

,

), And the specific criterion for selecting the reference terminal at this time is the correlation matrix (Equation 8)

Determinant using

It can be defined as.

는 참조문헌 1[M. Sharif and B. Hassibi, "On the capacity of mimo broadcast channel with partial side information", IEEE Trans. Inf. Theory, vol. 51, no. 2, pp. 506-522, 2005.]에 의해 아래 [수식 8]을 만족한다.At this time,

Reference 1 [M. Sharif and B. Hassibi, "On the capacity of mimo broadcast channel with partial side information", IEEE Trans. Inf. Theory, vol. 51, no. 2, pp. 506-522, 2005. satisfies Equation 8 below.

Equation 8

은 참고문헌 2[G. Strang, “Linear Algebra and Its Applications,” Brooks/Cole, 2006, pp.237-240.]에 의해

이 되며,

의 최대값에 대한 boundary 값은 위 참고문헌 1에 의해 아래 [수식 9]를 만족한다.Right from above [Equation 8]

Is described in Ref. 2 [G. Strang, “Linear Algebra and Its Applications,” Brooks / Cole, 2006, pp. 237-240.

Becomes

The boundary value for the maximum value of is satisfied by Equation 9 below by Ref.

[Equation 9]

where

개의 단말 중 어떤 단말이 기준단말그룹으로 선택될 수 있는지 결정하기 위해, 각 단말의

이 임계 값 보다 큰지 작은지 판단해야 하는데, 이때의 임계 값

를 [수식 9]의

값으로 정한다.At this time,

To determine which of the terminals can be selected as the reference terminal group, each terminal

You need to determine if it is greater or less than this threshold,

Of Equation 9

Set by value.

은

의 최대값에 대한 lower bound 값보다 큰 단말들의 집합이다.In other words, the terminals belonging to the reference terminal group

silver

Is a set of terminals larger than the lower bound value for the maximum value of.

를 이용하여, 기준단말그룹(

)에 속하는 각 단말을 아래 [수식 10]에서와 같이 선택할 수 있다.Furthermore, the threshold

By using the reference terminal group (

Each terminal belonging to) can be selected as shown in Equation 10 below.

Equation 10

The configuration unit 12 performs a function of configuring a subgroup for each reference terminal in the reference terminal group.

More specifically, when the generation of the reference terminal group through the selection of the reference terminal is completed, the configuration unit 12 selects a terminal capable of simultaneously transmitting data with the reference terminal in the reference terminal group for each terminal belonging to the reference terminal group Configure subgroups.

In this case, the configuration unit 12 may configure a subgroup by sequentially selecting terminals from the reference terminal group for each terminal belonging to the reference terminal group, as many terminals as possible for simultaneous transmission of data by the base station apparatus 10.

Meanwhile, in the subgroup configuration, the configuration unit 12 sequentially selects a terminal having channel information orthogonal to each previously selected terminal after the reference terminal is first selected for each subgroup, and in particular, the previous terminal. When two or more terminals having channel information orthogonal to each selected terminal may select a terminal having the highest determinant value of the correlation matrix among the two or more terminals.

In summary, for example, as shown in FIG. 4 (b), when the reference terminal group as shown in FIG. 4 (b) is generated, the first terminal Z ₁ is selected from the reference terminal group in FIG. 4 (c). Subsequently, a subgroup # 1 may be configured by sequentially selecting a next terminal having channel information orthogonal to the previously selected terminal, and in particular, the subgroup configuration process may include all terminals z ₁ and z in the reference terminal group. ₂ , ..., z _r ) may be repeated to be the first terminal, and subgroups # 1, # 2, ..., #r may be configured for each terminal in the reference terminal group.

The determination unit 13 determines a simultaneous transmission group among subgroups for each reference terminal.

More specifically, when the configuration of the subgroup for each reference terminal in the reference terminal group is completed, the determination unit 13 checks the performance indicators according to simultaneous data transmission for each subgroup, and the result indicates that the maximum performance indicator is The subgroup to be determined is a simultaneous transmission group.

In this case, the sum rate of each subgroup may receive data predicted for each terminal in the subgroup when simultaneous transmission of data of each terminal for each subgroup through block diagonal precoding. It can refer to the sum of the performance, which can be understood through the process of deriving the sum rate in [Equation 7] described above.

For better understanding of the description, the operation of the configuration unit 12 for configuring the above-described subgroups and the operation of the determination unit 13 for determining the simultaneous transmission group will be described in more detail with reference to the following equation.

First, when at least some of the terminals z ₁ , z ₂ ,..., Z _r satisfying a specific condition whose determinant value of the correlation matrix is greater than or equal to a threshold value are selected, an initialization process is performed to configure a subgroup. This initialization process can be understood as the process of [Equation 11] to [Equation 13] below.

[Equation 11]

Equation 12

Equation 13

를 초기 선택하고,

를 update하는 아래 [수식 14] 내지 [수식 16]의 초기선택과정을 처리할 수 있으며, 여기서,

는 단말

로 전송할 다운링크 데이터로 이해될 수 있다.When this initialization process is completed, as the reference terminal in the reference terminal group,

Initial selection,

To update the process of the initial selection process of [Equation 14] to [Equation 16] below, where,

Terminal

It can be understood as downlink data to be transmitted to.

[Equation 14]

Equation 15

[Formula 16]

과 orthogonal한 행렬

를 계산하는 직교성분석과정을 처리한다.Also, once this initial selection process is complete, for each user

And orthogonal matrix

Process the orthogonal analysis process to calculate.

에서

는 orthogonal matrices의 집합이며,

는 아래 [수식 17]과 같이 정의될 수 있다.At this time,

in

Is a set of orthogonal matrices,

May be defined as in Equation 17 below.

[Equation 17]

,

,

와 orthogonal한

component를 구하는 수식으로서, 참조문헌 3[T. Oh, S. Hyeon, H. Go, S. Choi, "A user selection algorithm providing maximum sum-rate for multiuser mimo system," IEICE Trans. on Commun., vol.E93-B, no.5, pp.1302-1305, May 2010.]으로부터 이해될 수 있으며,

는

를 SVD한 식

에서

의 처음

columns으로 이루어진 행렬을 의미한다.Where Equation 17 is

With orthogonal

As an expression for obtaining a component, reference 3 [T. Oh, S. Hyeon, H. Go, S. Choi, "A user selection algorithm providing maximum sum-rate for multiuser mimo system," IEICE Trans. on Commun., vol. E93-B, no. 5, pp. 1302-1305, May 2010.

Is

SVD expression

in

First time

A matrix of columns.

를 아래 [수식 18] 과 같이 update 해주는 후보단말업데이트과정을 처리하게 되는데, 이는 다음 단말을 선택할 때 set

을 통해 이전에 선택된 단말들의 채널 정보와 직교(orthogonal)한 채널정보를 갖는 단말 중 다음 사용자를 선택하기 위함이다.In addition, when this orthogonality analysis process is completed,

The process of updating the candidate terminal to update as shown in [Equation 18] below, which is set when selecting the next terminal

This is to select a next user among terminals having channel information orthogonal with channel information of previously selected terminals.

Equation 18

번째 사용자를 선택하고,

와

를 업데이트하는 추가선택과정을 다음 [수식 19] 내지 [수식 21]을 통해 처리한다.Furthermore, when the candidate terminal update process is completed, the next terminal in the subgroup, that is,

The first user,

Wow

The additional selection process for updating the is processed through the following [Equation 19] to [Equation 21].

Formula 19

Equation 20

[Equation 21]

라면,

을 하고 전술의 직교성분석과정으로 이동하게 되며, 그렇지 않은 경우

의 sum rate (

)를 [수식 7]을 이용해서 계산할 수 있다.At this time,

Ramen,

And move on to the orthogonal analysis of tactics, otherwise

Sum rate (

) Can be calculated using Equation 7.

라면,

,

로 설정하고 전술의 초기선택과정으로 이동하여 이후 과정을 반복하게 되며, 그렇지 않은 경우, 즉, 기본단말그룹 내 모든 단말에 대한 서브그룹이 생성된 경우라면, 가장 큰 sum rate (

)을 갖는

를 찾아,

에 해당하는 서브그룹을 최적의 서브그룹(optimal user set) 즉, 동시전송그룹으로 선택하는 다음 [수식 22] 및 [수식 23]의 과정을 처리할 수 있다.Also,

Ramen,

,

Set to and go to the initial selection process described above to repeat the subsequent process, otherwise, that is, if the subgroup is generated for all the terminals in the basic terminal group, the largest sum rate (

Having

Find it,

The process of the following [Equation 22] and [Equation 23] of selecting the subgroup corresponding to the optimal subgroup (optimal user set), that is, the simultaneous transmission group may be processed.

 Formula 22

Formula 23

The transmitter 14 performs a function of transmitting data to each terminal in the simultaneous transmission group.

More specifically, when the simultaneous transmission group is determined from a subgroup for each reference terminal in the reference terminal group, the transmitter 14 performs block diagonalization precoding for each data of each terminal in the determined simultaneous transmission group. After processing, the base station apparatus transmits the data to each terminal in the simultaneous transmission group through the antenna.

As described above, according to the configuration of the base station apparatus 10 according to an embodiment of the present invention, when selecting the first terminal in order to sequentially select the terminal, instead of selecting a single terminal, based on a specific criterion By selecting a primary user group, error propagation, which is a problem of the existing terminal selection method, can be minimized. In addition, all the terminals included in the reference terminal group are repeated so as to serve as the first terminal, to form as many subgroups as the number of terminals included in the reference terminal group, the highest performance index (sum rate) By determining the subgroup as the final simultaneous transmission group, it is possible to improve the performance index (sum rate) in simultaneous data transmission.

Hereinafter, a method of operating the base station apparatus 10 according to an embodiment of the present invention will be described with reference to FIG. 5.

First, the generation unit 11 generates a reference terminal group by selecting a terminal satisfying a specific criterion among the plurality of terminals located in the coverage of the base station apparatus 10 as the reference terminal (S11-S12).

In this case, the generation unit 11 may select a reference terminal based on the channel information of each of the plurality of terminals, the channel information is related to the downlink channel between the base station apparatus and the terminal, between the antenna of the base station apparatus and the antenna of the terminal It can be expressed as a channel matrix for the channel of.

Here, the channel information is received from each of the plurality of terminals together with the eigen values of the correlation matrix based on the dimension of the channel matrix. In particular, the correlation matrix here is to be used as a specific condition for selecting a reference terminal. Can be.

In summary, when the channel information is received from the plurality of terminals, the generation unit 11 determines whether the determinant value of the correlation matrix based on the received channel information is greater than or equal to the threshold value, and the determination result determines that the determinant value is critical. The terminal that is greater than or equal to the value can be selected as the reference terminal belonging to the reference terminal group.

In other words, as shown in FIG. 4A, the specific condition that the determinant value of the correlation matrix among the entire terminals 1, 2,..., K _T located in the coverage of the base station apparatus 10 is greater than or equal to a threshold value. At least some of the terminals Z ₁ , Z ₂ ,..., Z _r satisfying the C ₁ may be selected to generate a reference terminal group as shown in FIG. 4 (b).

Subsequently, when the generation of the reference terminal group through selection of the reference terminal is completed, the configuration unit 12 selects a terminal capable of simultaneously transmitting data with the reference terminal in the reference terminal group for each terminal belonging to the reference terminal group. A group is formed (S13).

In this case, the configuration unit 12 may configure a subgroup by sequentially selecting terminals from the reference terminal group for each terminal belonging to the reference terminal group, as many terminals as possible for simultaneous transmission of data by the base station apparatus 10.

Meanwhile, in the subgroup configuration, the configuration unit 12 sequentially selects a terminal having channel information orthogonal to each previously selected terminal after the reference terminal is first selected for each subgroup, and in particular, the previous terminal. When two or more terminals having channel information orthogonal to each selected terminal may select a terminal having the highest determinant value of the correlation matrix among the two or more terminals.

In other words, as shown in FIG. 4 (b), when the reference terminal group as shown in FIG. 4 (b) is generated, the first terminal Z ₁ is selected from the reference terminal group in FIG. 4 (c). Subsequently, a subgroup # 1 may be configured by sequentially selecting a next terminal having channel information orthogonal to the previously selected terminal, and in particular, the subgroup configuration process may include all terminals z ₁ , in the reference terminal group. z ₂ , ..., z _r ) may be repeated to be the first terminal, and subgroups # 1, # 2, ..., #r may be configured for each terminal in the reference terminal group.

Furthermore, when the configuration of the subgroups for each reference terminal in the reference terminal group is completed, the determination unit 13 confirms the performance indicators according to simultaneous data transmission for each subgroup, and the result indicates that the performance index becomes the maximum. The group is determined to be a simultaneous transmission group (S14-S15).

In this case, the sum rate of each subgroup may receive data predicted for each terminal in the subgroup when simultaneous transmission of data of each terminal for each subgroup through block diagonal precoding. It can refer to the sum of the performance, which can be understood through the process of deriving the sum rate in [Equation 7] described above.

Subsequently, when a simultaneous transmission group is determined from subgroups of each reference terminal in the reference terminal group, the transmitter 14 processes block diagonalization precoding for data of each terminal in the determined simultaneous transmission group. Thereafter, the base station apparatus transmits simultaneously to each terminal in the simultaneous transmission group through the antenna (S16).

As described above, according to the operation method of the base station apparatus 10 according to an embodiment of the present invention, when selecting the first terminal in order to sequentially select the terminal, rather than selecting a single terminal, based on a specific criterion By selecting a primary user group, error propagation, which is a problem of the existing terminal selection method, can be minimized. In addition, all the terminals included in the reference terminal group are repeated so as to serve as the first terminal, to form as many subgroups as the number of terminals included in the reference terminal group, the highest performance index (sum rate) By determining the subgroup as the final simultaneous transmission group, it is possible to improve the performance index (sum rate) in simultaneous data transmission.

On the other hand, the operation method of the base station apparatus 10 according to an embodiment of the present invention, may be implemented in the form of program instructions that can be executed by various computer means may be recorded on a computer readable medium. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. Program instructions recorded on the media may be those specially designed and constructed for the purposes of the present invention, or they may be of the kind well-known and available to those having skill in the computer software arts. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic disks, such as floppy disks. Magneto-optical media, and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like. The hardware device described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

Although the present invention has been described in detail with reference to preferred embodiments, the present invention is not limited to the above-described embodiments, and the present invention belongs to the present invention without departing from the gist of the present invention as claimed in the following claims. Anyone skilled in the art will have the technical idea of the present invention to the extent that various modifications or changes are possible.

According to an operation method of a base station apparatus and a base station apparatus according to the present invention, it is possible to improve the performance index (sum rate) of simultaneous data transmission in a multi-user multiple-input multiple-output (MU-MIMO) downlink environment. However, the invention is an industrially available invention because the possibility of marketing or operating the applied device is not only sufficient for the use of the related technology as well as the use of the related technology as well as the degree to which it can be clearly realized in reality.

10: base station apparatus
11: generator 12: component
13: decision unit 14: transmission unit
20: terminal (user)

Claims (12)

A generation unit for generating a reference terminal group by selecting one or more reference terminals based on channel information of each of the plurality of terminals;
A configuration unit configured to select at least one terminal capable of simultaneously transmitting data with the reference terminal in the reference terminal group and configure a subgroup for each reference terminal in the reference terminal group; And
And a determination unit which determines, as a simultaneous transmission group, a subgroup in which a performance index according to simultaneous data transmission is maximum among the subgroups for each reference terminal. The method of claim 1,
The channel information,
Regarding the downlink channel between the base station apparatus and the terminal, the channel matrix of the channel between the antenna of the base station apparatus and the antenna of the terminal is represented.
The generation unit,
And selecting a terminal having a determinant value of a correlation matrix based on the dimension of the channel matrix as a reference terminal as a reference terminal to generate a reference terminal group. The method of claim 1,
The component part,
And selecting each reference terminal in the reference terminal group as the first terminal in the subgroup. The method of claim 1,
The component part,
And a terminal having channel information orthogonal to each previously selected terminal after sequentially selecting the first reference terminal for each subgroup. The method of claim 2,
The component part,
When the reference terminal for each subgroup is first selected and there are two or more terminals having channel information orthogonal to each previously selected terminal, the terminal is configured by selecting the terminal having the highest determinant value among the two or more terminals. Base station apparatus, characterized in that. The method of claim 1,
The performance index,
The base station apparatus, characterized in that the base station apparatus is defined as the total sum of data reception performance predicted for each terminal when the data of each terminal is simultaneously transmitted for each subgroup through Block Diagonalization Precoding. . Generating a reference terminal group by selecting one or more reference terminals based on channel information of each of the plurality of terminals;
A subgroup configuration step of configuring a subgroup by selecting at least one terminal capable of simultaneously transmitting data with the reference terminal in the reference terminal group for each reference terminal in the reference terminal group; And
And a simultaneous transmission group determining step of determining, as a simultaneous transmission group, a subgroup in which a performance index according to simultaneous data transmission is maximum among the subgroups for each reference terminal. The method of claim 7, wherein
The channel information is,
Regarding the downlink channel between the base station apparatus and the terminal, the channel matrix of the channel between the antenna of the base station apparatus and the antenna of the terminal is represented.
The reference terminal group creation step,
And selecting a terminal having a determinant value of a correlation matrix based on the dimension of the channel matrix as a reference terminal as a reference terminal to generate a reference terminal group. The method of claim 7, wherein
The subgroup configuration step,
And selecting each reference terminal in the reference terminal group as the first terminal in the subgroup. The method of claim 7, wherein
The subgroup configuration step,
And after selecting the first reference terminal for each subgroup, sequentially selecting terminals having channel information orthogonal to each previously selected terminal. The method of claim 8,
The subgroup configuration step,
When the reference terminal for each subgroup is first selected and there are two or more terminals having channel information orthogonal to each previously selected terminal, a terminal is configured by selecting a terminal having the highest determinant value among the two or more terminals. Operation method of a base station apparatus, characterized in that. The method of claim 7, wherein
The performance index,
The base station apparatus, characterized in that the base station apparatus is defined as the total sum of data reception performance predicted for each terminal when the data of each terminal is simultaneously transmitted for each subgroup through Block Diagonalization Precoding. Method of operation.

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