KR20160063253A - Scheduling method and apparatus of multi-antenna communication system, and method and apparatus for feeding-back channel quality indicator - Google Patents

Abstract

A method is provided in which a UE feeds back a CQI (channel quality indicator). The terminal receives at least one reference signal from at least one of the plurality of beams of the base station from the base station. The UE measures a signal-to-interference plus noise ratio (SINR) for the at least one reference signal. The UE determines a first level corresponding to the measured SINR among the levels of the first CQI. The UE feeds back the first CQI having the first level to the base station.

Description

TECHNICAL FIELD The present invention relates to a scheduling method and apparatus for a multi-antenna communication system, and a channel quality indicator (CQI) feedback method and apparatus.

The present invention relates to a method and apparatus for performing scheduling in a multi-antenna communication system, and a method and apparatus for feedback of a channel quality indicator (CQI).

In a cellular mobile communication system, the quality of a radio channel varies depending on the position and the speed of the terminal. The base station and the terminal perform transmission and reception through a control channel and a traffic channel for each transmission time interval (TTI) with a modulation order and a code rate appropriate for the quality of a propagation channel.

To this end, the terminal feeds back a channel quality indicator (CQI) to the base station by referring to a reference signal transmitted by the base station for use in the propagation channel estimation. In multi-user MIMO (MU-MIMO) communication to expand the throughput of a single user multiple-input multiple-output (SU-MIMO) communication used to increase the peak user rate of a UE or a sector throughput, It is fed back as a parameter for adaptive transmission.

In the long term evolution (LTE) standard of the 3GPP (3 ^rd generation partnership project), 16 CQI levels fed back by the UE are defined. Each CQI level is mapped to a modulation coding scheme (MCS) level for demodulation or decoding of each communication device. Each MCS level is mapped to a particular signal-to-interference plus noise ratio (SINR).

Recently, a mobile communication method using a millimeter wave (mmWave) band has been studied for 5G (5 ^th generation) mobile communication. In the millimeter wave band, the path attenuation increases more than the low frequency band, so a transmit / receive beam forming technique is basically used. In the millimeter wave band, due to the relatively small wavelengths, more antennas can be used than the frequency band of 2G (2 ^nd generation) mobile communications. As a result, it is possible to transmit a large number of streams simultaneously in the millimeter wave band. As the number of simultaneously transmitted streams increases, the interference between the streams may increase. In particular, since the CQI feedback scheme of the LTE MU-MIMO can not accurately estimate the interference amount of the paired streams, the MU-MIMO performance can be significantly degraded. Therefore, in order to smoothly operate the MU-MIMO, it is necessary to newly define the CQI that the UE feeds back, unlike the existing LTE.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and apparatus for newly defining a CQI in a multi-antenna communication system and feeding back a newly defined CQI.

It is another object of the present invention to provide a method and apparatus for downlink scheduling using a newly defined CQI.

According to an embodiment of the present invention, a method is provided in which a UE feeds back a CQI (channel quality indicator). The CQI feedback method of the UE includes receiving at least one reference signal from at least one of the plurality of beams of the base station from the base station; Measuring a signal-to-interference plus noise ratio (SINR) for the at least one reference signal; Determining a first level corresponding to the measured SINR among the levels of the first CQI; And feeding back the first CQI having the first level to the base station.

The first CQI may indicate an SINR that is greater than a maximum SINR that a second CQI used for data transmission of the base station may represent.

The CQI feedback method of the UE may further include receiving CQI feedback mode information from the base station.

The step of determining the first level may include determining an SINR increase according to the number of bits of the first CQI and the level of the first CQI based on the CQI feedback mode information. And determining a first level corresponding to the measured SINR among the determined number of bits and the level of the first CQI having the determined increased SINR.

The number of bits of the first CQI may be greater than the number of bits of the second CQI.

The number of bits of the first CQI may be equal to the number of bits of the second CQI and the SINR mapped to the level of the first CQI may increase steadily as the level of the first CQI increases.

The number of bits of the first CQI may be equal to the number of bits of the second CQI and the SINR increase in which the SINR mapped to the level of the first CQI increases with the level of the first CQI, The higher the level, the higher the level can be.

The minimum SINR that can be represented by the first CQI may be smaller than the minimum SINR that the second CQI can represent.

According to another embodiment of the present invention, a method is provided in which a base station transmitting data using a plurality of beams in a multi-antenna communication system performs scheduling. The base station scheduling method includes receiving, from a plurality of terminals, a first channel quality indicator (CQI) for at least one of the plurality of beams; Calculating a second CQI using the first CQI, the second CQI having a bit number less than the first CQI; Determining a first modulation coding scheme (MCS) level for a first one of the plurality of terminals using the second CQI; And transmitting data to the first terminal based on the first MCS level.

The maximum signal-to-interference plus noise ratio (SINR) that can be represented by the first CQI may be greater than the maximum SINR that the second CQI can represent.

The minimum SINR that can be represented by the first CQI may be smaller than the minimum SINR that the second CQI can represent.

Wherein the calculating the second CQI comprises: determining a first beam to apply to the first one of the plurality of beams based on the first CQI; Determining a second one of the plurality of beams to act as an interference to the first beam; And calculating a SINR for the first beam using a first CQI for the second beam and a first CQI for the first beam in the first CQI.

The calculating the second CQI may further include determining the second CQI corresponding to the SINR for the first beam.

The determining the first MCS level may include determining the first MCS level corresponding to the second CQI.

According to yet another embodiment of the present invention, a method is provided in which a base station transmitting data using multiple beams in a multi-antenna communication system performs scheduling. The BS scheduling method includes: informing a plurality of UEs of a first feedback mode to be applied to the plurality of UEs among a plurality of CQI feedback modes; Receiving a first channel quality indicator (CQI) according to the first feedback mode for at least one of the plurality of beams from the plurality of terminals receiving the reference signal of the base station through the plurality of beams; Calculating a second CQI with a maximum signal-to-interference plus noise ratio (SINR) less than a maximum SINR of the first CQI using the first CQI; And determining a first modulation coding scheme (MCS) level for a first one of the plurality of terminals using the second CQI.

According to an embodiment of the present invention, a multi-antenna base station transmits a reference signal, and a plurality of terminals can measure a downlink channel quality based on a reference signal and feedback the base station.

Also, according to an embodiment of the present invention, a multi-antenna BS can perform MIMO scheduling based on channel quality fed back from a UE.

Also, according to the embodiment of the present invention, a CQI considering interference can be obtained in a communication system in which a plurality of interference occurs.

Also, according to an embodiment of the present invention, the base station can increase the communication capacity by performing interference-considered scheduling using the feedback CQI from the UE.

1 is a diagram showing the relationship between CQI and SINR.
2 is a diagram illustrating a method by which a base station performs MU-MIMO scheduling.
3 is a diagram illustrating a method for transmitting data using a plurality of beams in a mobile communication base station in a millimeter wave band.
4 is a diagram illustrating a CQI according to an embodiment of the present invention.
5 is a diagram illustrating a CQI according to another embodiment of the present invention.
6 is a diagram illustrating a CQI according to another embodiment of the present invention.
FIG. 7A is a diagram illustrating a method for a UE to feedback a newly defined CQI to a base station according to an embodiment of the present invention. Referring to FIG.
7B is a diagram illustrating a method of performing scheduling using a feedback CQI from a UE according to an embodiment of the present invention.
8 is a diagram illustrating a method by which a base station informs a terminal of a CQI feedback mode according to an embodiment of the present invention.
9 is a diagram showing a configuration of a base station according to an embodiment of the present invention.
10 is a diagram showing a configuration of a terminal according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, a terminal is referred to as a mobile terminal (MT), a mobile station (MS), an advanced mobile station (AMS), a high reliability mobile station A mobile subscriber station (SS), a portable subscriber station, an access terminal (AT), a user equipment (UE) AMS, HR-MS, SS, mobile subscriber station, AT, UE, and the like.

In addition, the base station (BS) includes an advanced base station (ABS), a high reliability base station (HR-BS), a node B, an evolved node B an eNodeB, an access point (AP), a radio access station (RAS), a base transceiver station (BTS), a mobile multihop relay (MMR) a BS, an ABS, a HR-BS, a Node B, a BS, a relay station (RS), a high reliability relay station (HR-RS) eNodeB, AP, RAS, BTS, MMR-BS, RS, HR-RS, repeater, macro base station, small base station and the like.

1 is a diagram showing the relationship between CQI and SINR.

The number of levels that a CQI can have is K upper case. Each CQI level is mapped to a SINR value. For example, the level k (CQI-k) of the CQI is mapped to the SINR value (SINR1) and the level K (CQI-K) of the CQI is mapped to the maximum SINR value SINRmax1.

In the LTE standard, K = 16 is defined.

2 is a diagram illustrating a method by which a base station performs MU-MIMO scheduling.

Among the MU-MIMO communication methods of LTE or LTE-A (LTE-Advanced), there is a precoding technique. In the precoding scheme, a UE selects one code vector based on a codebook and a propagation channel, and feeds back a CQI according to the selected code vector to the base station. Hereinafter, LTE or LTE-A is referred to as LTE for convenience of explanation.

2, the base station transmits the code vector C1 and the code vector C2 (the code vector C1 and the code vector C2), which are fed back by the terminal UE1 and the terminal UE2, ), And performs MU-MIMO scheduling.

However, since the channels H1 and H2 of the terminals UE1 and UE are not perfectly orthogonal to each other like the code vectors C1 and C2, the stream transmitted through the code vector C1 is a code vector C2, Lt; RTI ID = 0.0 > UE2 < / RTI > This interference may lower the channel quality than the CQI initially fed back from the UE2 and may eventually increase the block error rate (BLER).

Hereinafter, embodiments of the present invention will be described by taking a mobile communication system operating in a millimeter wave band as an example. However, this is only an example, and the embodiment of the present invention can be applied to a mobile communication system operating in a frequency band other than the millimeter wave band.

3 is a diagram illustrating a method for transmitting data using a plurality of beams in a mobile communication base station in a millimeter wave band.

As illustrated in FIG. 3, the base station BS1 transmits a plurality of fixed beams BE1a through BE1h. Specifically, the base station BS1 allocates the same transmission resources to the plurality of beams BE1a to BE1h, and uses at least one of the plurality of beams BE1a to BE1h to generate a plurality of beams BE1a to BE1h And transmits data to the terminals.

When each data is transmitted simultaneously to the UEs UE3 and UE4 belonging to a region of a plurality of neighboring beams BE1b and BE1g in the MU-MIMO scheme, interference is likely to occur in the corresponding data. Therefore, the base station BS1 should be able to perform MU-MIMO scheduling considering this interference in advance.

As one of methods for considering interference, a terminal estimates an SINR considering interference of another beam (s) with respect to a specific beam using reference signals of a plurality of fixed beams received by the terminal, and outputs the estimated SINR as a CQI (Hereinafter, referred to as a 'method M10') in which the CQI is fed back to the base station.

As another method for considering interference, a terminal feeds back a beam-by-beam SINR (the SINR of each beam received by the terminal) in which interference of other beams is not taken to the base station, Method M20 '). In this case, since the UE does not consider the interference, it is necessary to feed back the SINR corresponding to the highest MCS level or higher that is supported in the mobile communication system to the base station. Also, in this case, it is preferable that the terminal can feed back to the base station an SINR corresponding to a minimum MCS level supported in the mobile communication system.

Hereinafter, a method of defining a new CQI for the method M20 and a method of scheduling using the newly defined CQI will be described in detail.

4 is a diagram illustrating a CQI according to an embodiment of the present invention.

The graph GR1b represents a set of CQIs of existing (LTE standard, etc.). Specifically, graph GR1b shows the SINR mapped to each of the K upper CQI levels. The base station refers to the CQI of the graph GR1b at the time of data transmission. Hereinafter, for convenience of explanation, the CQI for data transmission referred to by the base station during data transmission is referred to as tCQI. At each tCQI level, the SINR corresponding to the MCS level is mapped. For example, the level k (tCQI-k) of tCQI is mapped to the SINR value (SINR1) and the level K (tCQI-K) of tCQI is mapped to the maximum SINR value SINRmax1.

The graph GR1a represents a CQI set (set) to be measured and fed back by the UE. Hereinafter, for convenience of explanation, the feedback CQI to be fed back by the terminal is referred to as fCQI. Specifically, graph GR1b represents the SINR mapped to each of the CQI levels of L (where L> K). The number of bits of fCQI may be greater than the number of bits of tCQI. Through this, the SINR region in which fCQI is responsible (i.e., the SINR range that fCQI can represent) can be increased. Specifically, the level k (fCQI-k) of the fCQI is mapped to the SINR value (SINR1), the level K (fCQI-K) of the fCQI is mapped to the SINR value (SINRmax1) Is mapped to the SINR maximum value (SINRmax2). For example, if the maximum SINR value (SINRmax1) that can be represented by tCQI is about 22 dB, the maximum SINR value (SINRmax2) that fCQI can represent may be 30 dB or more.

On the other hand, FIG. 4 illustrates a case where the maximum SINR value corresponding to the highest level of fCQI is larger than the maximum SINR value corresponding to the highest level of tCQI. Likewise, the minimum SINR value corresponding to the lowest level of fCQI may be less than the minimum SINR value corresponding to the lowest level of tCQI. That is, the minimum SINR value that can be represented by fCQI may be smaller than the minimum SINR value that tCQI can represent. This is to extend the SINR range in which tCQI is responsible both in the high and low regions.

On the other hand, as the level maximum value of fCQI (fCQI-L) and the number of bits of fCQI are larger, more accurate interference reflection becomes possible and transmission performance is further improved. However, in determining the maximum level of the fCQI (fCQI-L) and the number of bits of the fCQI, the radio channel and modulation order of the communication system and the appropriate signal to noise ratio (SNR) ) Should be considered. For example, when all of these factors are considered, if tCQI is 4 bits, fCQI is preferably 5 bits.

The base station refers to the fCQI fed back by the terminal and calculates the SINR of the terminal. Specifically, in calculating the SINR of a corresponding terminal by referring to the fCQI fed back by the terminal, the base station can calculate the SINR of the corresponding terminal by reflecting interference caused by a plurality of transmission beams selected by the base station. Then, the base station converts the calculated SINR into a tCQI to be actually referred to at the time of data transmission.

Specifically, the base station can use the following Equation (1) at the time of tCQI conversion.

은 빔 인덱스 j를 제외한 모든 빔 인덱스 n에 대한 합(summation)을 나타낸다.In Equation (1), j represents the index of the beam to be transmitted by the base station, and n represents the index of a beam acting as an interference to the beam having index j (hereinafter referred to as " interference beam for index j beam. The number of interfering beams for the beam of index j may be zero or one or more. In Equation (1)

Represents a summation for all beam indices n except for beam index j.

In Equation (1), sinr () is a function for converting (mapping) fCQI to a log scale SINR value. In Equation (1), fCQI _j represents the fCQI for the beam of index j and fCQI _n represents the fCQI for the beam of index n.

The UE measures the strength of all beams available to it, converts it to fCQI, and feeds it back to the base station. Specifically, the terminal measures the intensity of each of the received beams, judges the beam whose measured intensity is equal to or greater than the threshold value as an effective beam, aligns the effective beam according to the measured intensity, Lt; RTI ID = 0.0 > fCQI < / RTI > Alternatively, the terminal may measure the intensity of each of the received beams, align the beam according to the measured intensity, and feedback the fCQI for a predetermined number of beams among the aligned beams to the base station.

The BS refers to the fCQI received from the UEs, schedules a beam suitable for each UE, and obtains the SINR of each of the scheduled beams (the beam having the index j) using Equation (1). Then, the base station maps each of the SINRs calculated using Equation (1) to tCQI. That is, the base station determines tCQI (tCQI of the beam having the index j) to be mapped to the obtained SINR. The base station finally maps each of tCQI (tCQI of the beam having the index j) to the MCS level. That is, the base station determines the MCS level (the MCS level of the beam having index j) mapped to tCQI. The base station transmits data to each of the terminals according to the MCS level.

On the other hand, as illustrated in FIG. 4, the SINR difference between the fCQI levels may be constant. That is, the slope of the graph GR1a may be constant. For example, the difference between the SINR value that is mapped to level k-1 (fCQI-k-1) of fCQI and the SINR value that is mapped to level k (fCQI-k) of fCQI is the level k (fCQI- And the SINR value mapped to the level k + 1 (fCQI-k + 1) of the fCQI (the SINR increase according to the level of the fCQI is constant).

5 and 6 are diagrams illustrating CQIs according to another embodiment of the present invention.

To reduce system overhead, the number of bits (e.g., 4 bits) of fCQI may be equal to the number of bits (e.g., 4 bits) of tCQI. That is, the number of levels that fCQI can have is equal to the number of levels that tCQI can have. However, as illustrated in Figs. 5 and 6, the SINR region covered by fCQI (the SINR range that fCQI can represent) is wider than the SINR region covered by tCQI (the SINR range that tCQI can represent).

On the other hand, since fCQI should cover an SINR area wider than tCQI, the SINR difference between fCQI levels is larger than the SINR difference between tCQI levels, as illustrated in Figs. 5 and 6.

Specifically, as illustrated in FIG. 5, the SINR difference between the fCQI levels may be constant. That is, the slope of the graph GR2a may be constant. For example, the difference between the SINR value that is mapped to level k-1 (fCQI-k-1) of fCQI and the SINR value that is mapped to level k (fCQI-k) of fCQI is the level k (fCQI- And the SINR value mapped to the level k + 1 (fCQI-k + 1) of the fCQI (the SINR increase according to the level of the fCQI is constant). On the other hand, as illustrated in graph GR2a, the maximum level K (fCQI-K) of fCQI is mapped to the SINR value (SINRmax2), while the maximum level K tCQI-K) is mapped to the SINR value (SINRmax1).

On the other hand, as illustrated in FIG. 6, the SINR difference between the fCQI levels may become larger as the CQI level becomes higher. That is, the slope of the graph GR3a may have a larger value as the CQI level becomes higher. For example, the difference between the SINR value that is mapped to level k (fCQI-k) of fCQI and the SINR value that is mapped to level k + 1 (fCQI-k + 1) of fCQI is the level k- may be greater than the difference between the SINR value mapped to the fCQI and the SINR value mapped to the level k (fCQI-k) of fCQI (the increase in the SINR depending on the level of fCQI becomes larger). On the other hand, as illustrated in graph GR3a, the maximum level K (fCQI-K) of fCQI is mapped to the SINR value (SINRmax2), while the maximum level K tCQI-K) is mapped to the SINR value (SINRmax1).

On the other hand, the MCS level conversion method based on Equation (1) described above can also be applied to the embodiment illustrated in FIG. 5 and FIG. That is, the base station can convert the fCQI according to the embodiment of FIG. 5 or 6 into the MCS level using Equation (1).

5 and 6 illustrate a case where the maximum SINR value corresponding to the highest level of fCQI is larger than the maximum SINR value corresponding to the highest level of tCQI. Likewise, the minimum SINR value corresponding to the lowest level of fCQI may be less than the minimum SINR value corresponding to the lowest level of tCQI. This is to extend the SINR range in which tCQI is responsible both in the high and low regions.

The CQI feedback procedure of the UE and the scheduling procedure of the BS when the newly defined fCQI and tCQI are used as described above will be described in detail with reference to FIGS. 7A, 7B, and 8.

FIG. 7A is a diagram illustrating a method for a UE to feedback a newly defined CQI to a base station according to an embodiment of the present invention. Referring to FIG.

The terminal measures the SINR for each beam with respect to the reference signal of each beam it receives (S10).

The terminal converts (maps) the beam-specific SINR to the fCQI level (S11). That is, the UE determines the fCQI level for each beam mapped to the beam-specific SINR.

The terminal feeds m (1? M) of the fCQI levels per beam to the base station through the uplink (S12). Specifically, the UE may sort the fCQI level for each beam according to the size, and may feed back an upper part of the sorted beam-by-beam fCQI levels to the base station.

7B is a diagram illustrating a method of performing scheduling using a feedback CQI from a UE according to an embodiment of the present invention.

The base station receives the fCQIs from the plurality of terminals and collects the received fCQIs (S20).

The base station performs terminal scheduling considering interference using the collected fCQI (S21). Specifically, the base station selects terminals to be subjected to spatial multiplexing in a specific TTI (according to scheduling), and calculates interference with reference to fCQIs fed back from selected terminals (S21). For example, the BS can obtain the SINR for each beam to be applied to the selected MSs using Equation 1 described above.

The base station finally determines the MCS level for each terminal using the calculated interference (S22). Specifically, as described above, the base station can convert the beam-specific SINR to the beam-specific tCQI and convert the beam-specific tCQI to the beam-specific MCS level (or MCS level per terminal).

The base station transmits data to each of the terminals in a specific TTI according to each determined MCS level (S23).

8 is a diagram illustrating a method by which a base station informs a terminal of a CQI feedback mode according to an embodiment of the present invention.

The base station transmits the fCQI feedback mode to the mobile station (S30). Specifically, the base station can inform the UEs of the fCQI feedback mode illustrated in FIG. 4, the fCQI feedback mode illustrated in FIG. 5, and the fCQI feedback mode illustrated in FIG. 6 to the UEs through an upper message.

The terminal feeds back the fCQI to the base station according to the fCQI feedback mode determined by the base station (S31). Specifically, all terminals can feed back the fCQI obtained according to the same fCQI feedback mode to the base station. Also, the terminal can determine the SINR increase width according to the number of bits of fCQI and the level of fCQI based on the fCQI feedback mode.

The base station performs scheduling using the fCQI received from the UEs as described above.

Meanwhile, the base station can determine which of the plurality of fCQI feedback modes to use semi-static considering the uplink overhead and the like.

9 is a diagram showing a configuration of a base station 100 according to an embodiment of the present invention.

The base station 100 includes a processor 110, a memory 120, and an RF converter 130.

The processor 110 may be configured to implement the procedures, functions and methods associated with the base station described herein.

The memory 120 is coupled to the processor 110 and stores various information related to the operation of the processor 110. [

RF converter 130 is coupled to processor 110 and transmits or receives radio signals.

10 is a diagram showing a configuration of a terminal 200 according to an embodiment of the present invention.

The terminal 200 includes a processor 210, a memory 220, and an RF converter 230.

The processor 210 may be configured to implement the procedures, functions and methods associated with the terminal described herein.

The memory 220 is coupled to the processor 210 and stores various information related to the operation of the processor 210. [

The RF converter 230 is connected to the processor 210 and transmits or receives a radio signal. The terminal 200 may have a single antenna or multiple antennas.

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, It belongs to the scope of right.

Claims (20)

As a method for the UE to feedback the CQI (channel quality indicator)
Receiving from the base station at least one reference signal through at least one of the plurality of beams of the base station;
Measuring a signal-to-interference plus noise ratio (SINR) for the at least one reference signal;
Determining a first level corresponding to the measured SINR among the levels of the first CQI; And
And feeding back a first CQI having the first level to the base station,
The first CQI may indicate a SINR that is greater than a maximum SINR that a second CQI used for data transmission of the BS may represent
CQI feedback method of the terminal. The method according to claim 1,
Further comprising receiving CQI feedback mode information from the base station,
Wherein the determining the first level comprises:
Determining an SINR increase according to the number of bits of the first CQI and the level of the first CQI based on the CQI feedback mode information; And
Determining a first level corresponding to the measured SINR among the levels of the first CQI having the determined number of bits and the determined SINR increment
CQI feedback method of the terminal. The method according to claim 1,
Wherein the number of bits of the first CQI is larger than the number of bits of the second CQI
CQI feedback method of the terminal. The method according to claim 1,
The number of bits of the first CQI is equal to the number of bits of the second CQI,
The SINR mapped to the level of the first CQI increases steadily as the level of the first CQI increases
CQI feedback method of the terminal. The method according to claim 1,
The number of bits of the first CQI is equal to the number of bits of the second CQI,
The SINR increase in which the SINR mapped to the level of the first CQI increases with the level of the first CQI increases as the level of the first CQI increases
CQI feedback method of the terminal. The method according to claim 1,
Wherein the minimum SINR that can be represented by the first CQI is smaller than a minimum SINR that the second CQI can represent
CQI feedback method of the terminal. CLAIMS What is claimed is: 1. A method for scheduling a base station transmitting data using multiple beams in a multi-antenna communication system,
Receiving, from a plurality of terminals, a first channel quality indicator (CQI) for at least one of the plurality of beams;
Calculating a second CQI using the first CQI, the second CQI having a bit number less than the first CQI;
Determining a first modulation coding scheme (MCS) level for a first one of the plurality of terminals using the second CQI; And
Transmitting data to the first terminal based on the first MCS level
Wherein the scheduling method comprises the steps of: 8. The method of claim 7,
The maximum signal-to-interference plus noise ratio (SINR) that can be represented by the first CQI is greater than the maximum SINR that can be represented by the second CQI
A method of scheduling a base station. 8. The method of claim 7,
Wherein the minimum SINR that can be represented by the first CQI is smaller than a minimum SINR that the second CQI can represent
A method of scheduling a base station. 9. The method of claim 8,
Wherein the calculating the second CQI comprises:
Determining a first beam to apply to the first one of the plurality of beams based on the first CQI;
Determining a second one of the plurality of beams to act as an interference to the first beam; And
Calculating a SINR for the first beam using a first CQI for the second beam and a first CQI for the first one of the first CQIs,
A method of scheduling a base station. 11. The method of claim 10,
Wherein the calculating the second CQI comprises:
Further comprising determining the second CQI corresponding to the SINR for the first beam,
Wherein determining the first MCS level comprises:
And determining the first MCS level corresponding to the second CQI
A method of scheduling a base station. 11. The method of claim 10,
Wherein calculating the SINR for the first beam comprises:
Calculating an SINR for the first beam using Equation 1 below,
A method of scheduling a base station.
[Equation 1]

(k: index of the first beam, SINR _k : SINR for the first beam, n: index of the second beam, fCQI _n : first CQI for the second beam, fCQI _k : A first CQI for the first CQI, sinr (): a function for calculating an SINR corresponding to the first CQI) CLAIMS What is claimed is: 1. A method for scheduling a base station transmitting data using multiple beams in a multi-antenna communication system,
The method comprising: informing a plurality of UEs of a first feedback mode to be applied to the plurality of UEs among a plurality of CQI feedback modes;
Receiving a first channel quality indicator (CQI) according to the first feedback mode for at least one of the plurality of beams from the plurality of terminals receiving the reference signal of the base station through the plurality of beams;
Calculating a second CQI with a maximum signal-to-interference plus noise ratio (SINR) less than a maximum SINR of the first CQI using the first CQI; And
Determining a first modulation coding scheme (MCS) level for a first one of the plurality of terminals using the second CQI
Wherein the scheduling method comprises the steps of: 14. The method of claim 13,
The number of bits of the first CQI is equal to the number of bits of the second CQI,
The SINR mapped to the CQI level of the first CQI increases steadily as the CQI level increases
A method of scheduling a base station. 14. The method of claim 13,
The number of bits of the first CQI is equal to the number of bits of the second CQI,
The increase in the SINR mapped to the CQI level of the first CQI according to the CQI level increases as the CQI level increases
A method of scheduling a base station. 14. The method of claim 13,
The number of bits of the first CQI is greater than the number of bits of the second CQI,
The SINR mapped to the CQI level of the first CQI increases steadily as the CQI level increases
A method of scheduling a base station. 14. The method of claim 13,
Wherein the calculating the second CQI comprises:
Determining a first beam to apply to the first one of the plurality of beams based on the first CQI;
Determining a second one of the plurality of beams to act as an interference to the first beam; And
Calculating a SINR for the first beam using a first CQI for the second beam and a first CQI for the first one of the first CQIs,
A method of scheduling a base station. 18. The method of claim 17,
Wherein calculating the SINR for the first beam comprises:
Calculating an SINR for the first beam using Equation 1 below,
A method of scheduling a base station.
[Equation 1]

(k: index of the first beam, SINR _k : SINR for the first beam, n: index of the second beam, fCQI _n : first CQI for the second beam, fCQI _k : A first CQI for the first CQI, sinr (): a function for calculating an SINR corresponding to the first CQI) 18. The method of claim 17,
Further comprising transmitting data to the first terminal based on the first MCS level,
Wherein the calculating the second CQI comprises:
Further comprising determining the second CQI corresponding to the SINR for the first beam,
Wherein determining the first MCS level comprises:
And determining the first MCS level corresponding to the second CQI
A method of scheduling a base station. 14. The method of claim 13,
Wherein the minimum SINR that can be represented by the first CQI is smaller than a minimum SINR that the second CQI can represent
A method of scheduling a base station.

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