KR101439731B1 - Apparatus and method for communication with terminal using a plurality of antennas - Google Patents

Abstract

There is provided a communication apparatus for communicating with a terminal using a plurality of antennas. The communication apparatus includes an alignment unit for aligning the plurality of antennas according to a predetermined reference, a calculation unit for calculating a system capacity for each of a plurality of windows grouped by grouping the plurality of aligned antennas into a plurality of antenna groups, And a selection unit selecting a first window having the maximum system capacity among the plurality of windows.

Description

[0001] APPARATUS AND METHOD FOR COMMUNICATION WITH TERMINAL USING A PLURALITY OF ANTENNAS [0002]

The present invention relates to an apparatus and method for communicating with a terminal using a plurality of antennas, and more particularly, to a system and method for selecting some antennas among all antennas in a multi-user multi-input multi-output (MU- To a device and method for communicating with a user terminal.

Recently, a variety of techniques have been studied for selecting antennas in massive MIMO network systems for data communication.

In existing studies, a single-user MIMO network, in which a BS (Base Station) communicates with one MS (Single Mobile Station) at a time, is generally considered. However, recently, as the amount of communication through a network increases, interest in a multi-user multi-input multi-output (MU-MIMO) network system that simultaneously communicates with a plurality of users using a large number of transmission antennas Is increasing. In this case, block-diagonalization (BD) or zero-forcing precoding technology is mainly used to reduce the co-channel interface (CCI) between users.

Also, an "antenna selection technique" in which a part of all the antennas of the BS is selected and used for communication in the linear precoding based multiuser multi-antenna (MU-MIMO) network is proposed. The problem of optimally selecting some antennas of all antennas requires numerous iterative calculations. In particular, even in the case of the linear precoding techniques, complexity due to antenna selection combination may occur in processing matrix inversion for precoding matrices. Therefore, it is required to compensate for problems such as the size, price, and complexity of the equipment according to the use of the antenna.

According to one aspect of the present invention, there is provided a communication apparatus for communicating with a terminal using a plurality of antennas, comprising: an alignment unit for aligning the plurality of antennas according to a predetermined reference; A calculation unit for calculating a system capacity for each of the plurality of windows, and a selection unit for selecting a first window having the maximum system capacity among the plurality of windows.

According to an embodiment, the communication apparatus can transmit data to the terminal using antennas included in the first window.

According to an exemplary embodiment, each of the plurality of windows may be an antenna set in which S groups adjacent to each other in the order of the sorting, and S is a natural number.

According to one embodiment, the plurality of antennas may be at least a portion of a Massive Multi-Input Multi-Output associated with the communication device.

According to one embodiment, the communication device is associated with a Multi-User Massive Multi-Input Multi-Output (MU-MIMO) system, wherein the plurality of antennas comprises at least a portion .

According to one embodiment, the predetermined criteria may be determined based on multi-user channel gains in communication with the communication device.

According to one embodiment, the predefined criteria may be to sort the plurality of antennas in descending order from the antenna with the highest multi-user channel gain.

According to one embodiment, the selector may select the first window using a sliding window algorithm.

According to another aspect of the present invention, there is provided a communication method of a communication apparatus communicating with a terminal using a plurality of antennas, the method comprising the steps of: arranging the plurality of antennas according to a predetermined reference; Calculating a system capacity for each of a plurality of windows grouped into the plurality of windows; and selecting a first window having the maximum system capacity among the plurality of windows.

According to an exemplary embodiment, each of the plurality of windows may be an antenna set in which S groups adjacent to each other in the order of the sorting, and S is a natural number.

According to one embodiment, the predetermined criteria may be determined based on multi-user channel gains in communication with the communication device.

According to one embodiment, the predefined criteria may be to sort the plurality of antennas in descending order from the antenna with the highest multi-user channel gain.

According to one embodiment, the first window may be selected using a sliding window algorithm.

According to an exemplary embodiment, the method may further include transmitting data to the terminal using antennas included in the first window.

1 is a block diagram illustrating a communication device according to one embodiment.
2 is a conceptual diagram of an apparatus for communicating with a terminal using a plurality of antennas according to an embodiment.
3 is a conceptual diagram of an apparatus for communicating with a terminal using a plurality of antennas according to another embodiment.
4 is a diagram illustrating a first window selection process based on a sliding window algorithm according to an exemplary embodiment.
5 is a diagram illustrating efficiency of a communication apparatus according to an exemplary embodiment.
6 is a diagram showing the efficiency of a communication apparatus according to another embodiment.
7 is a flowchart illustrating a method of communicating with a terminal using a plurality of antennas according to an embodiment.

In the following, some embodiments will be described in detail with reference to the accompanying drawings. However, it is not limited or limited by these embodiments. Like reference symbols in the drawings denote like elements.

Although the terms used in the following description have selected the general terms that are widely used in the present invention while considering the functions of the present invention, they may vary depending on the intention or custom of the artisan, the emergence of new technology, and the like.

Also, in certain cases, there may be terms chosen arbitrarily by the applicant for the sake of understanding and / or convenience of explanation, and in this case the meaning of the detailed description in the corresponding description section. Therefore, the term used in the following description should be understood based on the meaning of the term, not the name of a simple term, and the contents throughout the specification.

Throughout the specification, the first window means an antenna group used for communication with a user terminal among a plurality of antennas existing in a network system, and the system capacity of the network system can be selected to be maximized.

1 is a block diagram illustrating a communication device 100 that communicates with a terminal using a plurality of antennas according to an embodiment.

The communication apparatus 100 is a technique for selecting an antenna in a multi-user multi-input multi-output (MU-MIMO) system in which data is simultaneously transmitted using a large amount of transmission antennas to a plurality of users Lt; / RTI >

Massive MIMO systems can greatly improve system performance by using a large number of antennas, but it requires baseband and RF parts as many as the number of antennas, which can lead to many problems in size, complexity, and equipment cost of the device.

These problems can be largely solved by a method of adaptively selecting and transmitting only a part of all N (N is a natural number) antennas.

However, in antenna selection, a complexity corresponding to _N C _S is generated due to a problem of combining, and the complexity increases further as the number N of all antennas becomes larger.

In addition, according to the beam forming method applied to the selected antenna, the amount of computation in the base station may increase exponentially, which is difficult to implement in an actual system.

In order to compensate for this, the communication apparatus 100 intends to propose an antenna selection and communication technique capable of improving complexity and cost increase even when a large number of antennas are used.

The communication device 100 may include an arrangement unit 110, a calculation unit 120, and a selection unit 130.

The alignment unit 110 may align the plurality of antennas according to predetermined criteria.

The predefined criteria may be determined based on the multi-user channel gain in communication with the communication device 100.

In addition, the predetermined criteria may be to sort the plurality of antennas in descending order from the antenna with the highest multi-user channel gain.

The calculation unit 120 may calculate a system capacity for each of a plurality of windows grouped by grouping the plurality of aligned antennas into a plurality of antenna groups.

Each of the plurality of windows may be an antenna set grouped into S (S is a natural number) antennas neighboring each other in the order of the alignment.

The selection unit 130 may select a first window having the maximum system capacity among the plurality of windows.

The communication device 100 may transmit data to the terminal using the antennas included in the first window selected by the selection unit 130. [

In this case, the selection unit 130 may select the first window using a sliding window algorithm.

A process of selecting the first window by the selection unit 130 using a sliding window algorithm will be described later with reference to FIG.

The plurality of antennas may be at least a portion of a Massive Multi-Input Multi-Output associated with the communication device 100.

Also, the communication device 100 is associated with a multi-user multi-antenna (MU-MIMO) system, where the plurality of antennas may be at least a portion of multiple antennas included in the system.

2 is a conceptual diagram of an apparatus for communicating with a terminal using a plurality of antennas according to an embodiment.

Referring to FIG. 2, in a multiuser multi-antenna (MU-MIMO) system, one base station having N transmit antennas can simultaneously communicate with K users.

In this case, each of the K users may have a plurality of antennas, but one receiving antenna is assumed in the embodiment of FIG.

In FIG. 2, S _i denotes a signal transmitted to the i-th user, and v _i denotes an N × 1 beamforming vector.

At this time, the overall transmission signal X can be represented by an N × 1 vector as shown in Equations (1) and (2).

However, in a multi-user beamforming scheme, the overall channel can be modeled as a matrix of K x N, which can be expressed by Equation (3).

는 j번째 베이스 스테이션(Base Station)과 i번째 사용자의 수신 안테나 간의 채널 계수(Channel Coefficient)를 의미한다.In Equation (3)

Denotes a channel coefficient between a j-th base station and a reception antenna of an i-th user.

는 1×N의 행 행렬(row matrix)로서 N개의 송신 안테나와 i번째 사용자 간의 전체 채널 계수를,

는 K×1의 열 행렬(column matrix)로서 j번째 송신 안테나와 K명의 사용자 간의 전체 채널 계수를 각각 나타낸다.Also,

Denotes a 1 × N row matrix, and the total channel coefficient between the N transmit antennas and the i-th user,

Is a K × 1 column matrix representing the total channel coefficients between the jth transmit antenna and K users, respectively.

When the transmission signal X is transmitted through the channel, the signal received by the i-th user may be expressed by Equation (4).

Where n _i is a random variable of additive white Gaussian noise with an average of 0 and a variance of 1.

The Single-to-Interface plus Noise Ratio (SINR) of the i-th user can be expressed by Equation (5).

In this case, all channel coefficients are complex Gaussian random values with an average of 0 and a variance of 1, and it is assumed that each channel coefficient is independent and has an identically distributed value.

Also, the channel coefficient includes a physical quantity with a very small rate of change with respect to time during one transmission interval, and it can be assumed that the channel coefficient is a random value for each transmission interval.

Meanwhile, the communication apparatus 100 may implement another embodiment in which the remaining antennas other than the selected S antennas selected for transmitting signals among the N antennas are not used, and this may be performed as shown in FIG. 3 .

와 같이 정렬할 수 있다.The communication device 100 uses the arranging unit 110 to evaluate N antennas according to a channel gain for all users,

As shown in FIG.

에 의해,

와 같이 지표화될 수 있다.The aligned channel vector

By this,

As shown in FIG.

The antennas to be used for communication by the communication device 100 among the indexed and aligned channel vectors may be selected through a sliding window based algorithm according to an embodiment.

A first window selection process based on a sliding window algorithm according to an exemplary embodiment may be described with reference to FIG.

The plurality of antennas aligned by the aligning unit 110 may be grouped into a plurality of antenna groups and configured by a plurality of windows.

For example, each of the plurality of windows may be an antenna set grouped into S (S is a natural number less than or equal to N) antennas neighboring each other in the order of the sorting.

The system capacity for each of the plurality of windows may be calculated through the calculation unit 120 and the first window to be used in the communication apparatus 100 may be selected based on the calculation result of the system capacity.

The first window means an antenna group used for communication with a user terminal among a plurality of antennas existing in a network system, and the system capacity of the network system can be selected to be maximized.

3, when S is set to one window in the order of sorting, a plurality of windows can be generated by constructing a window while moving by one antenna element in order.

Accordingly, the plurality of windows can be generated by N-S + 1 (where N is the total number of antennas, S is the number of antennas to be selected or the number of antennas constituting each window).

The SINR of the i-th user for the w-th window among the plurality of windows can be expressed by Equation (6).

는 S개의 안테나를 포함하고 있는 w번째 윈도우로부터 얻어진 i번째 사용자의 채널 계수를 의미하며, 이는 구체적으로 수학식 7과 같이 표현될 수 있다.here,

Denotes the channel coefficient of the i-th user obtained from the w-th window including S antennas, which can be expressed as Equation (7).

Also, c _{w, which} is the sum-rate of the total user transmission rates for the w-th window, can be calculated as shown in Equation (8).

Meanwhile, the selection unit 130 selects a window having the maximum system capacity among the plurality of windows.

Accordingly, a first window having S consecutive antennas with the highest sum-rate can be expressed as Equation (9).

를 평균함으로써 구할 수 있다.Finally, the overall average sum-rate with respect to H is given by Equation 10

. ≪ / RTI >

5 is a graph showing the sum-rate when the transmission antenna is N = 100 and the SNR is 0 dB, and FIG. 6 is a graph showing the sum-rate when the transmission antenna is N = 200, respectively.

Since noise is assumed to be unit-variance, the total transmit power P available at the base station (BS) can be described by SNR.

5A shows a case where the number of users is 10 (K = 10), and FIG. 5B shows a case where the number of users is 20 (K = 20).

5, the sum-rate decreases as the number S of antennas used for transmission decreases. This is because the array gain of the base station decreases.

When the number of users K increases, the graphs of 510 and 520 of FIG. 5B show a steep reduction than the graphs of 530 and 540 of FIG. 5 (a), indicating that each user achieves a sufficient gain I can not.

This can be understood to be due to the lack of an array as the user increases, but it can be seen that the method 540 by the communication device 100 still performs better than the unilateral method 530. [

The sum-rate for the case where the number of transmit antennas N increases is shown in FIG.

6A, it can be confirmed that the sum-rate of the scheme 620 by the communication apparatus 100 is higher than that when S = N = 200 when the number S of selected antennas is 195 .

In other words, it can be seen that the sum-rate in the antenna selection method by the communication device 100 is higher than the method 610 without the antenna selection.

This is because it can be more efficiently utilized by allocating the transmission power that is evenly allocated to the antennas having the low channel gain to the antennas having the high channel gain.

7 is a flowchart illustrating a communication method of a communication device 100 that communicates with a terminal using a plurality of antennas according to an embodiment.

In step 710, the alignment unit 110 may align the plurality of antennas according to predetermined criteria.

The predetermined criteria may be determined based on multi-user channel gains communicating with the communication device 100, and may be a method of aligning the plurality of antennas in descending order from the multi-user channel gain large antenna.

In operation 720, the aligning unit 110 may group the plurality of aligned antennas into a plurality of antenna groups, and configure the plurality of antennas as a plurality of windows.

Each of the plurality of windows may be an antenna set grouped into S (S is a natural number) antennas neighboring each other in the order of the alignment.

In step 730, the calculation unit 120 may calculate the system capacity for each of the plurality of windows.

In operation 740, the selection unit 130 may select a first window having the maximum system capacity among the plurality of windows.

The communication device 100 may transmit data to the terminal using the antennas included in the first window selected by the selection unit 130. [

In this case, the selection unit 130 may select the first window using a sliding window algorithm.

The plurality of antennas may be at least a portion of a Massive Multi-Input Multi-Output associated with the communication device 100.

Also, the communication device 100 is associated with a multi-user multi-antenna (MU-MIMO) system, where the plurality of antennas may be at least a portion of multiple antennas included in the system.

The apparatus described above may be implemented as a hardware component, a software component, and / or a combination of hardware components and software components. For example, the apparatus and components described in the embodiments may be implemented within a computer system, such as, for example, a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable array (FPA) A programmable logic unit (PLU), a microprocessor, or any other device capable of executing and responding to instructions. The processing device may execute an operating system (OS) and one or more software applications running on the operating system. The processing device may also access, store, manipulate, process, and generate data in response to execution of the software. For ease of understanding, the processing apparatus may be described as being used singly, but those skilled in the art will recognize that the processing apparatus may have a plurality of processing elements and / As shown in FIG. For example, the processing unit may comprise a plurality of processors or one processor and one controller. Other processing configurations are also possible, such as a parallel processor.

The software may include a computer program, code, instructions, or a combination of one or more of the foregoing, and may be configured to configure the processing device to operate as desired or to process it collectively or collectively Device can be commanded. The software and / or data may be in the form of any type of machine, component, physical device, virtual equipment, computer storage media, or device , Or may be permanently or temporarily embodied in a transmitted signal wave. The software may be distributed over a networked computer system and stored or executed in a distributed manner. The software and data may be stored on one or more computer readable recording media.

The method according to an embodiment may be implemented in the form of a program command that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions to be recorded on the medium may be those specially designed and configured for the embodiments or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; 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 machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. For example, it is to be understood that the techniques described may be performed in a different order than the described methods, and / or that components of the described systems, structures, devices, circuits, Lt; / RTI > or equivalents, even if it is replaced or replaced.

Therefore, other implementations, other embodiments, and equivalents to the claims are also within the scope of the following claims.

Claims (15)

A communication apparatus for communicating with a terminal using a plurality of antennas,
An arranging unit arranged to arrange the plurality of antennas in descending order based on a channel gain per user communicating with the communication device;
A calculation unit for calculating a system capacity for each of a plurality of windows grouped by grouping the plurality of aligned antennas into a plurality of antenna groups; And
Selecting a first window having the maximum system capacity among the plurality of windows using a sliding window algorithm,
. The method according to claim 1,
And transmits data to the terminal using antennas included in the first window. The method according to claim 1,
Wherein each of the plurality of windows is an antenna set grouped into S antennas adjacent to each other in the order of the sorting, and S is a natural number. The method according to claim 1,
Wherein the plurality of antennas is at least a part of a Massive Multi-Input Multi-Output associated with the communication device. The method according to claim 1,
Wherein the communication device is associated with a multi-user multi-input multi-output (MU-MIMO) system, the plurality of antennas being at least a part of multiple antennas included in the system. delete The method according to claim 1,
Wherein the arranging unit aligns the plurality of antennas in descending order from an antenna having a larger channel gain per multi-user. delete A communication method of a communication apparatus for communicating with a terminal using a plurality of antennas,
Arranging the plurality of antennas in descending order based on a channel gain per user communicating with the communication device;
Calculating system capacity for each of a plurality of windows grouped by grouping the plurality of aligned antennas into a plurality of antenna groups; And
Selecting a first window having the maximum system capacity among the plurality of windows using a sliding window algorithm
/ RTI > 10. The method of claim 9,
Wherein each of the plurality of windows is an antenna set grouped into S antennas adjacent to each other in the order of the sorting, and S is a natural number. delete 10. The method of claim 9,
Wherein the aligning step arranges the plurality of antennas in descending order from an antenna having a large channel gain per multi-user. delete 10. The method of claim 9,
Transmitting data to the terminal using antennas included in the first window
Lt; / RTI > A computer-readable recording medium storing a program for performing the communication method according to any one of claims 9, 10, 12, and 14.

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