KR102382912B1 - Scheduling method and apparatus of multi-antenna communication system, and method and apparatus for feeding-back channel quality indicator - Google Patents

Abstract

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

Description

Scheduling method and apparatus of a multi-antenna communication system, and CQI (channel quality indicator) feedback method and apparatus

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

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

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

In the long term evolution (LTE) standard of the ^3rd generation partnership project (3GPP), 16 CQI levels fed back by the terminal 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 specific signal-to-interference plus noise ratio (SINR).

Meanwhile, recently, for 5G ( ^5th generation) mobile communication, a mobile communication method using a millimeter wave (mmWave) band is being studied. Since path attenuation is increased in the millimeter wave band than in the low frequency band, a transmission/reception beamforming technique is basically used. In the millimeter wave band, due to the relatively small wavelength, a larger number of antennas may be used than the frequency band of 2 ^nd generation (2G) mobile communication. Due to this, it is possible to simultaneously transmit a large number of streams in the millimeter wave band. As the number of concurrently transmitted streams increases, interference between the streams may increase. In particular, since the CQI feedback method of LTE MU-MIMO cannot accurately estimate the amount of interference of paired streams, MU-MIMO performance may be greatly reduced. Therefore, for smooth operation of MU-MIMO, it is necessary to newly define the CQI fed back by the UE, unlike the existing LTE.

An object of the present invention is to provide a method and apparatus for newly defining CQI in a multi-antenna communication system and feeding back the newly defined CQI.

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

According to an embodiment of the present invention, a method for a UE to feed back a channel quality indicator (CQI) is provided. The CQI feedback method of the terminal includes: receiving, from a base station, at least one reference signal through at least one of a 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 first CQI levels; and feeding back a first CQI having the first level to the base station.

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

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

The determining of the first level may include: determining, based on the CQI feedback mode information, the number of bits of the first CQI and an SINR increase according to the level of the first CQI; and determining a first level corresponding to the measured SINR from among the first CQI levels having the determined number of bits and the determined SINR increase.

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 and the number of bits of the second CQI may be the same, and the SINR mapped to the level of the first CQI may constantly increase as the level of the first CQI increases.

The number of bits of the first CQI and the number of bits of the second CQI may be the same, and the SINR increase in which the SINR mapped to the level of the first CQI increases according to the level of the first CQI is the first CQI. The higher the level, the larger it can be.

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

In addition, according to another embodiment of the present invention, a method for performing scheduling by a base station transmitting data using a plurality of beams in a multi-antenna communication system is provided. The scheduling method of the base station may include: 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 having a smaller number of bits than the first CQI by using the first CQI; determining a first modulation coding scheme (MCS) level for a first terminal among the plurality of terminals by 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 the first CQI can represent 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 can be represented by the second CQI.

The calculating of the second CQI may include: determining a first beam to be applied to the first terminal among the plurality of beams based on the first CQI; determining a second beam acting as interference to the first beam among the plurality of beams; and calculating an SINR for the first beam by using a first CQI for the second beam and a first CQI for the first beam among the first CQIs.

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

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

In addition, according to another embodiment of the present invention, a method for performing scheduling by a base station transmitting data using a plurality of beams in a multi-antenna communication system is provided. The scheduling method of the base station includes the steps of notifying, to a plurality of terminals, a first feedback mode to be applied to the plurality of terminals among a plurality of CQI feedback modes; receiving a feedback of a first channel quality indicator (CQI) obtained according to the first feedback mode with respect to 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, using the first CQI, a second CQI having a maximum signal-to-interference plus noise ratio (SINR) that is smaller than a maximum SINR that the first CQI can represent; and determining a first modulation coding scheme (MCS) level for a first terminal among the plurality of terminals by using the second CQI.

According to an embodiment of the present invention, a multi-antenna base station may transmit a reference signal, and a plurality of terminals may measure downlink channel quality based on the reference signal and feed it back to the base station.

In addition, according to an embodiment of the present invention, the multi-antenna base station may perform MIMO scheduling based on the channel quality fed back from the terminal.

In addition, according to an embodiment of the present invention, it is possible to obtain a CQI in consideration of interference in a communication system in which a plurality of interferences occur.

In addition, according to an embodiment of the present invention, the base station can increase the communication capacity by performing scheduling in consideration of interference using the CQI fed back from the terminal.

1 is a diagram illustrating a relationship between CQI and SINR.
2 is a diagram illustrating a method for a base station to perform MU-MIMO scheduling.
3 is a diagram illustrating a method in which a mobile communication base station transmits data using a plurality of beams 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.
7A is a diagram illustrating a method in which a terminal feeds back a newly defined CQI to a base station according to an embodiment of the present invention.
7B is a diagram illustrating a method in which a base station performs scheduling using a CQI fed back from a terminal according to an embodiment of the present invention.
8 is a diagram illustrating a method for a base station to inform a terminal of a CQI feedback mode according to an embodiment of the present invention.
9 is a diagram illustrating a configuration of a base station according to an embodiment of the present invention.
10 is a diagram illustrating the configuration of a terminal according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings, the embodiments of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily implement them. However, the present invention may be embodied in several different forms and is not limited to the embodiments described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Throughout the specification, a terminal is a mobile terminal (MT), a mobile station (MS), an advanced mobile station (AMS), a high reliability mobile station (HR-MS) ), a subscriber station (subscriber station, SS), a portable subscriber station, an access terminal (AT), user equipment (UE), and the like, and may refer to a terminal, MT, MS, It may include all or part of the functions of AMS, HR-MS, SS, portable subscriber station, AT, UE, etc.

In addition, the base station (base station, BS), an advanced base station (advanced base station, ABS), a high reliability base station (high reliability base station, HR-BS), a Node B (node B), an advanced node B (evolved node B) , eNodeB), access point (AP), radio access station (radio access station, RAS), base transceiver station (BTS), MMR (mobile multihop relay)-BS, a repeater serving as a base station ( relay station, RS), a high reliability relay station (HR-RS) serving as a base station, may refer to a repeater, a macro base station, a small base station, etc., BS, ABS, HR-BS, Node B, It may include all or part of the functions of eNodeB, AP, RAS, BTS, MMR-BS, RS, HR-RS, repeater, macro base station, small base station, and the like.

1 is a diagram illustrating a relationship between CQI and SINR.

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

In the LTE standard, K=16 is defined.

2 is a diagram illustrating a method for a base station to perform MU-MIMO scheduling.

Among the MU-MIMO communication methods of LTE or LTE-A (LTE-Advanced), there is a precoding technique. In the precoding technique, the terminal 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, for convenience of description, LTE or LTE-A is referred to as LTE.

As illustrated in FIG. 2 , the base station has a code vector C1 and a code vector C2 fed back by a terminal UE1 and a terminal UE2 (the code vector C1 and the code vector C2 are orthogonal to each other) ) to perform 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 the code vector C2. It may act as interference to a stream transmitted to the UE2 through Such interference may lower the channel quality than the CQI initially fed back from the UE (UE2), and may eventually increase the block error rate (BLER).

Hereinafter, an embodiment of the present invention will be described using 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 may 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 in which a mobile communication base station transmits data using a plurality of beams in a millimeter wave band.

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

When each data is simultaneously transmitted to the UEs UE3 and UE4 belonging to an area of a plurality of neighboring beams BE1b and BE1g in the MU-MIMO method, interference is likely to occur in the corresponding data. Accordingly, the base station BS1 should be able to perform MU-MIMO scheduling in consideration of such interference in advance.

As one of the methods for considering interference, the UE estimates the SINR considering the interference of other beam(s) with respect to a specific beam by using the reference signals of several fixed beams it is receiving, and sets the estimated SINR as the CQI. There is a method of converting (mapping) and feeding back a CQI to the base station (hereinafter, 'method M10').

In addition, as another method for considering interference, the terminal feeds back the SINR for each beam (SINR of each beam received by the terminal) in which interference of other beams is not considered, and the base station considers the interference (hereinafter referred to as ' Method M20'). In this case, since the UE does not consider interference, it should be able to feed back the SINR corresponding to the highest MCS level or higher supported in the mobile communication system to the base station. Also in this case, it is preferable that the terminal can feed back the SINR corresponding to the lowest MCS level or less supported in the mobile communication system to the base station.

Hereinafter, a method of defining a new CQI for 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 an existing (LTE standard, etc.) CQI set. Specifically, the graph GR1b represents the SINR mapped to each of the K uppercase CQI levels. The base station refers to the CQI of the graph GR1b when transmitting data. Hereinafter, for convenience of description, the CQI for data transmission referred to by the base station during data transmission is referred to as tCQI. SINR corresponding to the MCS level is mapped to each tCQI level. 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 SINR maximum value (SINRmax1).

The graph GR1a represents a CQI set measured and fed back by the UE. Hereinafter, for convenience of description, the CQI for feedback fed back by the UE is referred to as fCQI. Specifically, the graph GR1b represents the SINR mapped to each of the CQI levels of L uppercase letters (where L>K). The number of bits of fCQI may be larger than the number of bits of tCQI. Through this, the SINR region covered by the fCQI (ie, the SINR range that the fCQI can represent) may be increased. Specifically, level k (fCQI-k) of fCQI is mapped to SINR value (SINR1), level K (fCQI-K) of fCQI is mapped to SINR value (SINRmax1), and level L (fCQI-L) of fCQI is mapped to 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 value (SINRmax2) that can be represented by fCQI may be 30 dB or more.

Meanwhile, FIG. 4 exemplifies a case in which the maximum SINR value corresponding to the highest level of fCQI is greater than the maximum SINR value corresponding to the highest level of tCQI. Similarly, the minimum SINR value corresponding to the lowest level of fCQI may be smaller 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 can be represented by tCQI. This is to extend the SINR range covered by tCQI in both the high region and the low region.

On the other hand, as the maximum level of fCQI (fCQI-L) and the number of bits of fCQI are large, more precise interference reflection is possible and transmission performance is further improved. However, in determining the maximum level of fCQI (fCQI-L) and the number of bits of fCQI, an appropriate signal to noise ratio (SNR) for a propagation channel and modulation order of a communication system, and a radio frequency (RF) implementation ) 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 calculates the SINR of the terminal with reference to the fCQI fed back by the terminal. Specifically, in calculating the SINR of the corresponding terminal with reference to the fCQI fed back by the terminal, the base station may calculate the SINR of the corresponding terminal by reflecting interference caused by a plurality of transmission beams selected by the base station. In addition, the base station converts the calculated SINR into tCQI to be actually referenced during data transmission.

Specifically, the base station may use the following Equation 1 during tCQI conversion.

은 빔 인덱스 j를 제외한 모든 빔 인덱스 n에 대한 합(summation)을 나타낸다.In Equation 1, j denotes an index of a beam that the base station intends to transmit, and n denotes an index of a beam acting as interference to a beam having index j (hereinafter, 'interfering beam with respect to a beam of index j'). The number of interference beams for the beam of index j may be 0 or 1 or more. In Equation 1,

denotes the sum of all beam indices n except for the 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 fCQI for the beam of index j, and fCQI _n represents fCQI for the beam of index n.

The terminal measures the strength of all beams valid for it, converts it into fCQI, and feeds it back to the base station. Specifically, the terminal measures the intensity of each beam it has received, determines a beam having a measured intensity equal to or greater than a threshold value as an effective beam, aligns the effective beam according to the measured intensity, and all or some of the aligned effective beams. fCQI may be fed back to the base station. Alternatively, the terminal may measure the intensity of each beam it receives, align the corresponding beam according to the measured intensity, and feed back fCQIs for a predetermined number of aligned beams to the base station.

The base station schedules a beam suitable for each terminal with reference to the fCQI fed back from the terminals, and obtains the SINR of each scheduled beam (beam having an index j) using Equation 1. And the base station maps each SINR obtained using Equation 1 to tCQI. That is, the base station determines tCQI (tCQI of the beam having index j) mapped to the obtained SINR. And, the base station finally maps each tCQI (tCQI of the beam having index j) to the MCS level. That is, the base station determines the MCS level (the MCS level of the beam having the index j) mapped to the tCQI. And the base station transmits data to each corresponding terminal according to each MCS level.

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

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

In order to reduce system overhead, the number of bits (eg, 4 bits) of fCQI may be the same as the number of bits (eg, 4 bits) of tCQI. That is, the number of levels that fCQI can have may be the same as the number of levels that tCQI can have. However, as illustrated in FIGS. 5 and 6 , the SINR region (SINR range that fCQI can represent) covered by fCQI is wider than the SINR region (SINR range that tCQI can represent) covered by tCQI.

On the other hand, since fCQI has to cover a wider SINR region than tCQI, as illustrated in FIGS. 5 and 6 , the SINR difference between fCQI levels is larger than the SINR difference between tCQI levels.

Specifically, as illustrated in FIG. 5 , the SINR difference between fCQI levels may be constant. That is, the slope of the graph GR2a may be constant. For example, the difference between the SINR value mapped to the level k-1 of fCQI (fCQI-k-1) and the SINR value mapped to the level k (fCQI-k) of the fCQI is the level k (fCQI-k) of the fCQI It is the same as the difference between the SINR value mapped to , and the SINR value mapped to the fCQI level k+1 (fCQI-k+1) (the SINR increase according to the fCQI level is constant). On the other hand, as illustrated in the graph GR2a, the maximum level K of fCQI (fCQI-K) is mapped to the SINR value (SINRmax2), whereas, as illustrated in the graph GR2b, the maximum level K of tCQI ( tCQI-K) is mapped to the SINR value (SINRmax1).

Meanwhile, as illustrated in FIG. 6 , the SINR difference between fCQI levels may become larger as the CQI level increases. That is, the slope of the graph GR3a may have a larger value as the CQI level increases. For example, the difference between the SINR value mapped to the level k of fCQI (fCQI-k) and the SINR value mapped to the level k+1 (fCQI-k+1) of the fCQI is the level k-1 (fCQI-k) of the fCQI. It may be larger than the difference between the SINR value mapped to k-1) and the SINR value mapped to the fCQI level k (fCQI-k) (the SINR increase according to the fCQI level increases). On the other hand, as illustrated in the graph GR3a, the maximum level K of fCQI (fCQI-K) is mapped to the SINR value (SINRmax2), whereas, as illustrated in the graph GR3b, the maximum level K of tCQI ( tCQI-K) is mapped to the SINR value (SINRmax1).

Meanwhile, the MCS level conversion method based on Equation 1 may be applied to the embodiment illustrated in FIGS. 5 and 6 as well. That is, the base station may convert the fCQI according to the embodiment of FIG. 5 or 6 to the MCS level using Equation 1 described above.

Meanwhile, FIGS. 5 and 6 illustrate a case in which the maximum SINR value corresponding to the highest level of fCQI is greater than the maximum SINR value corresponding to the highest level of tCQI. Similarly, the minimum SINR value corresponding to the lowest level of fCQI may be smaller than the minimum SINR value corresponding to the lowest level of tCQI. This is to extend the SINR range covered by tCQI in both the high region and the low region.

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

7A is a diagram illustrating a method in which a UE feeds back a newly defined CQI to a base station according to an embodiment of the present invention.

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

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

The UE feeds back m (however, 1≤m) of the fCQI levels for each beam to the base station through the uplink (S12). Specifically, the UE may align the fCQI levels for each beam according to their size, and feed back a part of the upper part of the aligned fCQI levels for each beam to the BS.

7B is a diagram illustrating a method in which a base station performs scheduling using a CQI fed back from a terminal according to an embodiment of the present invention.

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

The base station performs terminal scheduling in consideration of interference by using the aggregated fCQI (S21). Specifically, the base station selects terminals to be spatially multiplexed on a specific TTI (selected according to scheduling), and calculates interference by referring to fCQIs fed back from the selected terminals (S21). For example, the base station may obtain the SINR for each beam to be applied to the selected terminals using Equation 1 above.

The base station finally determines the MCS level for each terminal by using the calculated interference (S22). Specifically, as described above, the base station may convert the SINR for each beam into tCQI for each beam, and convert the tCQI for each beam into an MCS level for each beam (or MCS level for each UE).

The base station transmits data to each corresponding terminal at a specific TTI according to each determined MCS level (S23).

8 is a diagram illustrating a method for a base station to inform 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 terminal (S30). Specifically, the base station may inform the terminals of one 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, through a higher-order 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 may feed back the fCQI obtained according to the same fCQI feedback mode to the base station. In addition, the UE may determine the SINR increase according to the number of bits of the fCQI and the level of the fCQI based on the fCQI feedback mode.

As described above, the base station performs scheduling using the fCQI received from the terminals.

Meanwhile, the base station may semi-statically determine which of a plurality of fCQI feedback modes to use in consideration of uplink overhead and the like.

9 is a diagram illustrating 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 related to the base station described herein.

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

The RF converter 130 is connected to the processor 110 and transmits or receives a wireless signal.

10 is a diagram illustrating 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 procedures, functions, and methods related to the terminal described herein.

The memory 220 is connected 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 wireless signal. The terminal 200 may have a single antenna or multiple antennas.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the following claims are also provided. is within the scope of the right.

Claims (20)

As a method for the UE to feed back a CQI (channel quality indicator)
receiving, from a base station, at least one reference signal through at least one of a plurality of beams of the base station;
measuring a signal-to-interference plus noise ratio (SINR) for the at least one reference signal;
receiving CQI feedback mode information from the base station;
determining, based on the CQI feedback mode information, the number of bits of a first CQI and an SINR increase according to the level of the first CQI;
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 increase; and
and feeding back a first CQI having the first level to the base station,
The first CQI may indicate a larger SINR than the SINR that the second CQI used for data transmission of the base station can represent at most.
CQI feedback method of the terminal. delete According to claim 1,
The number of bits of the first CQI is greater than the number of bits of the second CQI
CQI feedback method of the terminal. According to claim 1,
The number of bits of the first CQI is the same as the number of bits of the second CQI,
The SINR mapped to the level of the first CQI constantly increases as the level of the first CQI increases.
CQI feedback method of the terminal. According to claim 1,
The number of bits of the first CQI is the same as the number of bits of the second CQI,
The SINR increase in which the SINR mapped to the level of the first CQI increases according to the level of the first CQI becomes larger as the level of the first CQI increases.
CQI feedback method of the terminal. According to claim 1,
The minimum SINR that can be represented by the first CQI is smaller than the minimum SINR that can be represented by the second CQI.
CQI feedback method of the terminal. A method for performing scheduling by a base station transmitting data using a plurality of beams in a multi-antenna communication system, the method comprising:
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 having a smaller number of bits than the first CQI by using the first CQI;
determining a first modulation coding scheme (MCS) level for a first terminal among the plurality of terminals by using the second CQI; and
Transmitting data to the first terminal based on the first MCS level
including,
The maximum signal-to-interference plus noise ratio (SINR) that the first CQI can represent is greater than the maximum SINR that the second CQI can represent,
Calculating the second CQI comprises:
determining a first beam to be applied to the first terminal among the plurality of beams based on the first CQI;
determining a second beam acting as interference to the first beam among the plurality of beams; and
and calculating an SINR for the first beam by using a first CQI for the second beam and a first CQI for the first beam among the first CQIs. delete 8. The method of claim 7,
The minimum SINR that can be represented by the first CQI is smaller than the minimum SINR that can be represented by the second CQI.
A scheduling method of a base station. delete 8. The method of claim 7,
Calculating the second CQI comprises:
Further comprising the step of determining the second CQI corresponding to the SINR for the first beam,
Determining the first MCS level comprises:
Comprising the step of determining the first MCS level corresponding to the second CQI
A scheduling method of a base station. 8. The method of claim 7,
Calculating the SINR for the first beam includes:
Using Equation 1 below, including calculating the SINR for the first beam
A scheduling method of 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, fCQI _k : for the first beam The first CQI for , sinr(): a function for calculating the SINR corresponding to the first CQI) A method for performing scheduling by a base station transmitting data using a plurality of beams in a multi-antenna communication system, the method comprising:
informing a plurality of terminals of a first feedback mode to be applied to the plurality of terminals among a plurality of CQI feedback modes;
receiving a feedback of a first channel quality indicator (CQI) obtained according to the first feedback mode with respect to 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, using the first CQI, a second CQI having a maximum signal-to-interference plus noise ratio (SINR) smaller than an SINR maximally represented by the first CQI; and
determining a first modulation coding scheme (MCS) level for a first terminal among the plurality of terminals by using the second CQI
includes,
Calculating the second CQI comprises:
determining a first beam to be applied to the first terminal among the plurality of beams based on the first CQI;
determining a second beam acting as interference to the first beam among the plurality of beams; and
calculating an SINR for the first beam by using a first CQI for the second beam and a first CQI for the first beam among the first CQIs
A scheduling method of a base station. 14. The method of claim 13,
The number of bits of the first CQI is the same as the number of bits of the second CQI,
The SINR mapped to the CQI level of the first CQI constantly increases as the CQI level increases.
A scheduling method of a base station. 14. The method of claim 13,
The number of bits of the first CQI is the same as 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 scheduling method of 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 constantly increases as the CQI level increases.
A scheduling method of a base station. delete 14. The method of claim 13,
Calculating the SINR for the first beam includes:
Using Equation 1 below, including calculating the SINR for the first beam
A scheduling method of 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, fCQI _k : for the first beam The first CQI for , sinr(): a function for calculating the SINR corresponding to the first CQI) 14. The method of claim 13,
Based on the first MCS level, further comprising the step of transmitting data to the first terminal,
Calculating the second CQI comprises:
Further comprising the step of determining the second CQI corresponding to the SINR for the first beam,
Determining the first MCS level comprises:
Comprising the step of determining the first MCS level corresponding to the second CQI
A scheduling method of a base station. 14. The method of claim 13,
The minimum SINR that can be represented by the first CQI is smaller than the minimum SINR that can be represented by the second CQI.
A scheduling method of a base station.

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