WO2017131268A1

WO2017131268A1 - Apparatus and method for scheduling antenna system

Info

Publication number: WO2017131268A1
Application number: PCT/KR2016/001044
Authority: WO
Inventors: 조동호; 이강민; 박진솔
Original assignee: 한국과학기술원
Priority date: 2016-01-29
Filing date: 2016-01-29
Publication date: 2017-08-03

Abstract

A scheduling apparatus according to an embodiment of the present invention comprises: an antenna selection unit for selecting an antenna from among a plurality of antennas in an antenna system in which a single radio frequency (RF) chain is connected to the plurality of antennas, such that a transmission capacity supported by the antenna system is maximized; and a determination unit for, when the antenna system allocates a plurality of streams to users served by the antenna system using the selected antenna, determining whether to allocate the plurality of streams to a single user or to distributively allocate the plurality of streams to each of a plurality of users.

Description

Apparatus and method for scheduling an antenna system

The present invention relates to an apparatus and method for scheduling an antenna system. More specifically, in an antenna system in which a single RF (chain) chain is connected to a plurality of antennas, an antenna is selected based on the channel environment of the antenna, and a plurality of streams are assigned to a single user or a plurality of users. An apparatus and method for providing a technique related to doing so are provided.

In the conventionally implemented multi-input multi-output (MIMO) system, the number of antennas is 2x2, 4x4 or 8x8 and so on. However, the massive MIMO system as the next generation system has a much larger number of antennas than the MIMO system implemented previously. Such a massive MIMO system may occupy a lot of space in that the number of antennas is larger than that of the existing MIMO system system.

On the other hand, the spread of smart phones is increasing the demand for small size repeaters and base stations. In addition, the development of the Internet of Things (IoT) technology is rapidly increasing the demand for small base stations capable of supporting high capacity. In other words, small cells are becoming the center of next generation systems.

Based on this, the next-generation system is evolving with the center of a small cell having a larger number of antennas than before. Accordingly, various efforts have been made to reduce the space occupied by the antenna while showing similar performance as before.

Among them, there is a study simulating a system with QAM modulation. According to this study, performance can be maintained similarly to the existing MIMO system, and the space occupied by the antenna can be reduced. However, this study is only the result of a virtual simulation of the system. Thus, results in real systems are likely not to be the same as in this study.

In addition, there is a study on a system applying a specific antenna pattern, for example, a basis pattern. However, this research has a problem in that it cannot be applied to other antenna patterns than the basis pattern.

The problem to be solved by the present invention is to provide a technique having a performance similar to the existing while reducing the space occupied by the antenna in an antenna system in which a single (RF) radio frequency chain is connected to a plurality of antennas. .

In addition, the present invention provides a technique for increasing diversity gain and transmission capacity in a MIMO system using a single RF chain.

However, the problem to be solved by the present invention is not limited thereto.

In a scheduling apparatus according to an embodiment of the present invention, in an antenna system in which a single radio frequency (RF) chain is connected to a plurality of antennas, a transmission capacity supported by the antenna system among the plurality of antennas is maximum. An antenna selection unit for selecting an antenna so that the antenna system allocates a plurality of streams to a user provided with the service by the antenna system using the selected antennas; And a determination unit for determining whether to allocate the plurality of streams to each of the plurality of users or to distribute the plurality of streams.

The antenna system may also be a multi-input multi-output (MIMO) system.

The antenna selector may be configured such that the maximum transmission capacity of the antenna system is maximized among antennas in which a ratio between a transmission capacity of an antenna supporting maximum transmission capacity and a transmission capacity of an antenna supporting minimum transmission capacity is equal to or less than a preset value. You can choose an antenna.

In addition, the transmission capacity of each of the plurality of antennas may be calculated based on the channel state of the antenna of each of the plurality of antennas.

The determining unit may be further configured to each of the plurality of users if there is a predetermined gain in distributing the plurality of streams to each of the plurality of users rather than allocating the plurality of streams to the single user. Can be distributedly allocated.

In addition, the determination unit may determine whether there is the predefined gain by comparing the size of the transmission capacity.

In a scheduling method according to an embodiment of the present invention, in an antenna system in which a single radio frequency (RF) chain is connected to a plurality of antennas, a transmission capacity supported by the antenna system among the plurality of antennas is maximum. Selecting an antenna, and when the antenna system allocates a plurality of streams to a user provided by the antenna system using the selected antenna, whether to assign the plurality of streams to a single user. And determining whether to distribute the plurality of streams to each of a plurality of users.

The antenna system may also be a multi-input multi-output (MIMO) system.

In the selecting of the antenna, the antenna system supports transmission from among antennas in which a ratio between a transmission capacity of an antenna supporting maximum transmission capacity and a transmission capacity of an antenna supporting minimum transmission capacity is equal to or less than a preset value. The antenna can be selected for maximum capacity.

In the selecting of the antenna, the transmission capacity of each of the plurality of antennas may be calculated based on a channel state of an antenna of each of the plurality of antennas.

The determining may include determining the plurality of users to each of the plurality of users if there is a predetermined gain in distributing the plurality of streams to each of the plurality of users rather than allocating the plurality of streams to the single user. The stream of can be distributed and allocated.

In addition, the determining may be determined by comparing the size of the transmission capacity whether or not there is a predetermined gain.

A computer program stored in a computer readable recording medium according to an embodiment of the present invention is an antenna system in which a single radio frequency (RF) chain is connected to a plurality of antennas. Selecting an antenna so that a maximum transmission capacity is supported, and when the antenna system allocates a plurality of streams to a user provided with the service by the antenna system using the selected antenna, And determining whether to allocate the plurality of streams or to distribute the plurality of streams to each of a plurality of users.

A computer-readable recording medium according to an embodiment of the present invention is an antenna system in which a single radio frequency (RF) chain is connected to a plurality of antennas, and a transmission capacity supported by the antenna system among the plurality of antennas is provided. Selecting an antenna to be the maximum, and when the antenna system allocates a plurality of streams to a user who is serviced by the antenna system using the selected antenna, the plurality of streams to a single user. A program may be recorded that includes a command to perform a step of determining whether to allocate or distribute the plurality of streams to each of a plurality of users.

According to an embodiment of the present invention, in a MIMO system to which a single RF chain is applied, a high transmission capacity may be obtained while guaranteeing a degree of freedom for each stream. In addition, in allocating a plurality of streams by determining whether to allocate a plurality of streams to a single user or to distribute a plurality of streams to each of the plurality of users by determining and assigning, it is possible to obtain a benefit in terms of transmission capacity. Star fairness can also be secured.

1 is a diagram illustrating a configuration of a scheduling apparatus according to an embodiment of the present invention.

2 is a diagram illustrating a process of selecting an antenna according to an embodiment of the present invention.

3 is a diagram illustrating a process of allocating a stream to a single user or a plurality of users according to an embodiment of the present invention.

4 is a diagram illustrating a procedure of a scheduling method according to an embodiment of the present invention.

Advantages and features of the present invention, and methods for achieving them will be apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various forms, and only the embodiments of the present invention make the disclosure of the present invention complete and the general knowledge in the technical field to which the present invention belongs. It is provided to fully convey the scope of the invention to those skilled in the art, and the present invention is defined only by the scope of the claims.

Referring to FIG. 1, the scheduling apparatus includes an antenna selector 110 and a determiner 120. However, since the scheduling apparatus is illustrated in FIG. 1, the inventive concept is not limited thereto.

First, the scheduling apparatus 100 may be installed in, for example, a base station or a repeater of a mobile communication system having a single radio frequency (RF) chain connected to a plurality of antennas. In this case, the antenna system may be a multi-input multi-output (MIMO) system, but is not limited thereto.

Meanwhile, the scheduling apparatus 100 and the antenna selector 110 and the determination unit 120 included in the scheduling apparatus 100 may store a memory for storing instructions programmed to perform an operation to be described below, and the instructions. It can be implemented by a microprocessor running.

The antenna selector 110 selects a preset number of antennas from the plurality of antennas included in the above-described antenna system. For example, the antenna selection unit 110 may select at least one or more, preferably two or more antennas.

The antenna selector 110 may select an antenna having the maximum total transmission capacity supported by the selected antenna based on the transmission capacity supported by each of the plurality of antennas. This allows the antenna system to have a maximum transmission capacity.

There may be a restriction on an antenna that the antenna selector 110 can select from among a plurality of antennas. For example, the antenna selector 110 may select from among antennas in which a ratio between a transmission capacity of an antenna that supports the maximum transmission capacity and a transmission capacity of an antenna that supports the minimum transmission capacity among a plurality of antennas is less than or equal to a preset value. . That is, the difference between the transmission capacities of the antenna supporting the maximum transmission capacity and the antenna supporting the minimum transmission capacity may be less than a specific level. In this case, the transmission capacity of each of the plurality of antennas may be calculated based on the channel state of each of the plurality of antennas, and the channel state of each of the plurality of antennas may be obtained by the scheduling apparatus 100 from the antenna system.

According to this, the transmission capacity is concentrated in a specific antenna, so that the antenna system has a maximum transmission capacity (total transmission capacity) and a smaller transmission capacity (total transmission capacity) than the first case. In the second case where the unselected antennas have a transmission capacity greater than or equal to a certain level, in one embodiment, the antenna selector 110 selects the antenna to be the second case. That is, even when sacrificing the aspect of the maximum transmission capacity, by selecting the antennas having a predetermined transmission capacity or more, it is possible to guarantee the degree of freedom of the antennas.

2 is a diagram exemplarily illustrating a process of selecting an antenna by the antenna selecting unit 110 as described above. Referring to FIG. 2, n is an identification number for a user using an antenna system, N is a total number of users, i is an identification number for a stream transmitted using the antenna, and H is a total of a plurality of antennas. A matrix indicating the channel state, S 'is a matrix indicating the antenna finally selected by the antenna selector, S is a matrix indicating the selectable antenna, s' _i is an antenna used when transmitting the i-th stream among the plurality of antennas Vector, p _i is the power allocated to the antenna, x _i is the i-th stream, || Hs' _i x _i || ² is the channel capacity (transmission capacity) when transmitting the i th stream x _i using an antenna determined by the s' _i matrix, σ is the noise power density of white noise, and I _n, _intra affects the i th stream. Means intra-cell interference.

According to FIG. 2, the antenna selector 110 selects an antenna so as to have a maximum transmission capacity when transmitting the i-th stream x _i among a plurality of antennas (for example, T) of the antenna system. In this case, the result of selecting the antenna may be represented by the antenna selection matrix s' _i . In addition, the antenna selector 110 may select from among antennas in which a ratio between a transmission capacity of an antenna that supports the maximum transmission capacity and a transmission capacity of an antenna that supports the minimum transmission capacity among a plurality of antennas is equal to or less than a preset value. k (HS _n x _n ) ≦ C indicates this. That is, k (HS _n x _n ) ≤ C indicates that antennas selected from among a plurality of antennas have a transmission capacity of an antenna having a maximum transmission capacity for the nth user and a transmission capacity of an antenna having a minimum transmission capacity for the nth user. It means that the condition should be less than the preset value C.

Referring back to FIG. 1, when allocating a plurality of streams to a user using the antenna selected by the antenna selecting unit 110, the determination unit 120 assigns the plurality of streams to a single user or a plurality of users. Determine whether to distribute to It will be described in more detail below.

The determination unit 120 compares when allocating a plurality of streams to a single user and when distributing a plurality of streams to each of the plurality of users. As a result of the comparison, when a plurality of streams are distributed to each of the plurality of users and there is a predetermined gain than when allocating a plurality of streams to a single user, the determination unit 120 distributes the plurality of streams to each of the plurality of users. To allocate. Here, the predefined gain may include, for example, the performance in transmission according to the channel state of the antenna, but is not limited thereto. In other words, if all four streams are allocated to user 1 and two of the streams have poor channel condition, the two users of channel n with poor channel condition have better channel condition. Allocating is more profitable. In this case, the determination unit 120 may allocate two streams among the four streams to user No. 1 and allocate the remaining two streams to user n times.

According to this, a plurality of streams can be allocated for each user according to the channel environment of the user, thereby obtaining a gain in terms of transmission capacity and ensuring fairness for each user.

The above operation of the above-described determination unit 120 may be performed by the following procedure, but this is merely an example, and thus the inventive concept is not limited thereto. First, the determination unit 120 selects a plurality of users who are to be provided with the service by the antenna system and assigns them a sequence number. In this case, the method of selecting a user and the method of assigning a sequence number may be based on a proportional fair scheduling method. According to the proportional fair scheduling method, a plurality of users may be selected as a whole more than a predetermined number of times. However, according to an embodiment, a procedure of selecting a user and assigning a sequence number by a proportional fair scheduling method may be omitted.

Next, the determining unit 120 first sets a plurality of streams to be assigned to the users having the fastest order.

Next, the determiner 120 determines whether there is a predefined gain when distributing a plurality of streams to the next user based on the user to whom the stream is assigned. As a result of the check, if there is a predefined gain, a plurality of streams are distributed and allocated to the user who has already been assigned the stream and the next user. This process is repeated for the remaining users.

Next, the determination unit 120 allocates a plurality of streams to the users set by the determination unit 120.

3 is a diagram exemplarily illustrating a process of determining whether the decision unit 120 allocates a plurality of streams to a single user or to a plurality of users, but this is merely an example, and thus the spirit of the present invention is limited thereto. It doesn't happen. In FIG. 3, U _m is an identifier indicating a user, and a total of N users may be selected by a proportional fair scheduling method. N _{o, m} is white noise and I _m is interference. In addition, C _m represents a transmission capacity when all K streams are allocated to the m th user.

In addition, C _{n, m} represents the transmission capacity when half of the K streams are allocated to the nth user instead of the mth user, and u _n is half of the K streams to the user other than the mth user. The other user n to indicate the maximum transmission capacity. Referring to Figure 3, C _m, that is transmitted in the case of allocating half of K streams to the m-th user than to assign all of the K streams to the m-th user and assign the other half of the K streams to n-th user If the capacity is larger, the user to which the plurality of streams are allocated becomes the m th user and the n th user. That is, if the transmission capacity is larger when allocating to a plurality of users than when allocating to a single user, the determination unit 120 allocates a plurality of streams to the plurality of users.

As described above, according to an embodiment, in a MIMO system to which a single RF chain is applied, a high transmission capacity may be obtained while guaranteeing a degree of freedom for each stream. In addition, in allocating a plurality of streams by determining whether to allocate a plurality of streams to a single user or to distribute a plurality of streams to each of the plurality of users by determining and assigning, it is possible to obtain a benefit in terms of transmission capacity. Star fairness can also be secured.

4 is a diagram illustrating a procedure of a scheduling method according to an embodiment of the present invention. The method illustrated in FIG. 4 may be performed by the scheduling apparatus illustrated in FIG. 1, and the portions described in FIGS. 1 to 3 may be applied as they are omitted. In addition, since the method shown in FIG. 4 is exemplary, the spirit of the present invention is not limited thereto.

Referring to FIG. 4, in a scheduling method according to an embodiment, a transmission capacity supported by the antenna system among the plurality of antennas in an antenna system in which a single radio frequency (RF) chain is connected to a plurality of antennas Selecting an antenna to be the maximum (S110), and when the antenna system allocates a plurality of streams to a user who is provided by the antenna system using the selected antenna, And determining whether to allocate a plurality of streams or to distribute the plurality of streams to each of a plurality of users (S120).

Selecting an antenna (S110) may select an antenna having a maximum total transmission capacity supported by the selected antenna based on a transmission capacity supported by each of the plurality of antennas. In this case, as described above, the ratio between the transmission capacity of the antenna that supports the maximum transmission capacity and the transmission capacity of the antenna that supports the minimum transmission capacity among the plurality of antennas may be selected from the antennas. In addition, the process of selecting the antenna shown in FIG. 2 is applicable to the step of selecting an antenna (S110).

Determining (S120) when assigning a plurality of streams to the user by using the antenna selected by the step of selecting the antenna (S110), whether to assign the plurality of streams to a single user or distributed to a plurality of users It is a step to decide whether or not to do it. More specifically, in the determining step (S120), when a plurality of streams are allocated to a single user and when a plurality of streams are distributed to each of the plurality of users, the comparison is made. As a result of the comparison, when a plurality of streams are distributed and allocated to each of the plurality of users, when the plurality of streams have a predefined gain than the plurality of allocations to a single user, the plurality of streams are distributed and allocated to each of the plurality of users. Here, the predefined gain may include, for example, the performance in transmission according to the channel state of the antenna, but is not limited thereto.

In addition, the process of determining whether to allocate the plurality of streams shown in FIG. 3 to a single user or to the plurality of users is applicable to the determining step (S120).

On the other hand, the scheduling method according to an embodiment of the present invention can be implemented as a computer program stored in a computer readable recording medium programmed to perform each step included in the method, and also performing each step included in the method It can also be implemented as a computer readable recording medium having recorded thereon a program including instructions.

Any reference to "an embodiment", "embodiment", "exemplary embodiment", or the like herein, means that a particular feature, structure, or characteristic described in connection with the embodiment is at least one of the present invention. It is meant to be included in the embodiment of. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment. In addition, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is within the understanding of those skilled in the art to affect that feature, structure, or characteristic with respect to other embodiments of the embodiment. I think.

Although the embodiments have been described in connection with many illustrative embodiments thereof, it should be understood that numerous other changes and embodiments may be devised by those skilled in the art that would fall within the spirit and scope of the principles of the invention. More specifically, various modifications and changes are possible in the component parts and / or arrangements of the subject combination arrangements within the scope of the present disclosure, the drawings and the appended claims. In addition to variations and modifications in component parts and / or arrangements, alternative uses will also be apparent to those skilled in the art.

Claims

An antenna selector configured to select an antenna such that a single radio frequency (RF) chain is connected to a plurality of antennas so that a transmission capacity supported by the antenna system is maximized among the plurality of antennas;

When the antenna system allocates a plurality of streams to a user who is serviced by the antenna system using the selected antenna, the plurality of streams may be allocated to a single user or the plurality of users, respectively. Determining unit for determining whether to distribute the stream distributed

Scheduling Device.
The method of claim 1,

The antenna system is a multi-input multi-output (MIMO) system.

Scheduling Device.
The method of claim 1,

The antenna selector,

Selecting an antenna so that the maximum transmission capacity supported by the antenna system among antennas whose ratio between the transmission capacity of the antenna supporting the maximum transmission capacity and the transmission capacity of the antenna supporting the minimum transmission capacity is less than or equal to a preset value

Scheduling Device.
The method of claim 3, wherein

Transmission capacity for each of the plurality of antennas,

It is calculated based on the channel state of the antenna each of the plurality of antennas

Scheduling Device.
The method of claim 1,

The antenna selecting unit selects an antenna by using the following equation.

Scheduling Device.

Where st || s i || = 1, K≥N, k (HS n x n ) ≤ C, p i ≥ 0, n is the identification number for the user using the antenna system, N is the total number of users, i is the stream transmitted using the antenna (stream) identification number, H is a matrix indicating the channel state for all the plurality of antennas, S 'is a matrix indicating the antenna finally selected by the antenna selection unit, S is a matrix indicating a selectable antenna, s i is a vector representing an antenna used to transmit an i-th stream among the plurality of antennas, pi is power allocated to the corresponding antenna, x i is an i-th stream, and || Hs' i x i || 2 is the channel capacity (transmission capacity) when the i-th stream x i is transmitted using the antenna determined by the s'i matrix, σ is the noise power density of white noise, and I n, intra affects the i-th stream. Means intra-cell interference.
The method of claim 1,

The determining unit,

When the plurality of streams are distributed and allocated to each of the plurality of users rather than allocating the plurality of streams to the single user, the plurality of users may be distributed and allocated to each of the plurality of users if there is a predetermined gain.

Scheduling Device.
The method of claim 6,

The determining unit,

Determining whether there is the predefined gain by comparing the size of the transmission capacity

Scheduling Device.
Selecting an antenna in a antenna system in which a single radio frequency (RF) chain is connected to a plurality of antennas so as to maximize a transmission capacity supported by the antenna system among the plurality of antennas;

When the antenna system allocates a plurality of streams to a user who is serviced by the antenna system using the selected antenna, the plurality of streams may be allocated to a single user or the plurality of users, respectively. Determining whether to distribute and distribute the stream;

Scheduling Method.
The method of claim 8,

The antenna system is a multi-input multi-output (MIMO) system.

Scheduling Method.
The method of claim 8,

Selecting the antenna,

Selecting an antenna such that the maximum transmission capacity supported by the antenna system is selected from the antennas in which the ratio between the transmission capacity of the antenna supporting the maximum transmission capacity and the transmission capacity of the antenna supporting the minimum transmission capacity is equal to or less than a preset value.

Scheduling Method.
The method of claim 10,

Selecting the antenna,

The transmission capacity for each of the plurality of antennas is calculated based on the channel state of the antenna each of the plurality of antennas has.

Scheduling Method.
The method of claim 8,

The selecting of the antenna may include selecting an antenna by using the following equation.

Scheduling Method.

Where st || s i || = 1, K≥N, k (HS n x n ) ≤ C, p i ≥ 0, n is an identification number for a user using an antenna system, i is an identification number for a stream transmitted using an antenna, H is a matrix representing channel states for all the plurality of antennas, and S 'is an antenna selection A matrix indicating the antenna finally selected by the negative, S is a matrix indicating the selectable antenna, s' i is a vector indicating the antenna used when transmitting the i-th stream of the plurality of antennas, p i is assigned to the antenna Power, x i is the i th stream, || Hs' i x i || 2 is the channel capacity (transmission capacity) when the i-th stream x i is transmitted using the antenna determined by the s' i matrix, σ is the noise power density of white noise, and I n, intra affects the i-th stream. Means intra-cell interference.
The method of claim 8,

The determining step,

When the plurality of streams are distributed and allocated to each of the plurality of users rather than allocating the plurality of streams to the single user, the plurality of users may be distributed and allocated to each of the plurality of users if there is a predetermined gain.

Scheduling Method.
The method of claim 13,

The determining step,

The group is determined and compared to the amount of transfer whether the defined capacity gain

Scheduling Method.
Selecting an antenna in a antenna system in which a single radio frequency (RF) chain is connected to a plurality of antennas so as to maximize a transmission capacity supported by the antenna system among the plurality of antennas;

When the antenna system allocates a plurality of streams to a user who is serviced by the antenna system using the selected antenna, the plurality of streams may be allocated to a single user or the plurality of users, respectively. Programmed to perform the step of determining whether to distribute the stream

A computer program stored on a computer readable recording medium.
Selecting an antenna in a antenna system in which a single radio frequency (RF) chain is connected to a plurality of antennas so as to maximize a transmission capacity supported by the antenna system among the plurality of antennas;

When the antenna system allocates a plurality of streams to a user who is serviced by the antenna system using the selected antenna, the plurality of streams may be allocated to a single user or the plurality of users, respectively. A program is written that includes instructions for performing the step of determining whether to distribute or distribute the stream.

Computer-readable recording medium.