WO2015147524A1 - Terminal, base station, and operation method thereof in distributed antenna system - Google Patents

Terminal, base station, and operation method thereof in distributed antenna system Download PDF

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Publication number
WO2015147524A1
WO2015147524A1 PCT/KR2015/002882 KR2015002882W WO2015147524A1 WO 2015147524 A1 WO2015147524 A1 WO 2015147524A1 KR 2015002882 W KR2015002882 W KR 2015002882W WO 2015147524 A1 WO2015147524 A1 WO 2015147524A1
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value
base station
terminal
method
transmission point
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PCT/KR2015/002882
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French (fr)
Korean (ko)
Inventor
남준영
고영조
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한국전자통신연구원
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Priority to KR20140034879 priority Critical
Priority to KR10-2014-0034879 priority
Priority to KR10-2014-0142858 priority
Priority to KR20140142858 priority
Priority to KR20140154769 priority
Priority to KR10-2014-0154769 priority
Application filed by 한국전자통신연구원 filed Critical 한국전자통신연구원
Priority to KR10-2015-0040572 priority
Priority to KR1020150040572A priority patent/KR20150111310A/en
Priority claimed from US15/128,695 external-priority patent/US20170111090A1/en
Publication of WO2015147524A1 publication Critical patent/WO2015147524A1/en

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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B7/00Radio transmission systems, i.e. using radiation field
    • H04B7/02Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/022Site diversity; Macro-diversity
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B17/00Monitoring; Testing
    • H04B17/20Monitoring; Testing of receivers
    • H04B17/24Monitoring; Testing of receivers with feedback of measurements to the transmitter
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B17/00Monitoring; Testing
    • H04B17/30Monitoring; Testing of propagation channels
    • H04B17/309Measuring or estimating channel quality parameters
    • H04B17/336Signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR]
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B7/00Radio transmission systems, i.e. using radiation field
    • H04B7/02Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/0413MIMO systems
    • H04B7/0417Feedback systems
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B7/00Radio transmission systems, i.e. using radiation field
    • H04B7/02Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0619Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side

Abstract

Disclosed are a terminal, a base station, and an operation method thereof in a distributed antenna system. A base station may include first and second transmission points located in different places. The base station transmits a reference signal for measuring a channel state to a terminal. The terminal calculates a first value which is a ratio of a signal transmitted to the terminal to noise, using the received reference signal. Further, the terminal calculates a second value which is a ratio of interference by a first transmission point to the noise and calculates a third value which is a ratio of interference by a second transmission point to the noise, using the received reference signal. The terminal transmits information on the first to third values to the base station.

Description

Terminal, Base Station and Operation Method in Distributed Antenna System

A terminal, a base station, and a method of operating the same in a distributed antenna system.

After 4G, mobile communication systems require 1000 times more frequency efficiency, 1000 times more energy efficiency, and 1000 times more device acceptance than 4G systems such as 3GPP LTE due to the rapid increase in data traffic. Physical layer technologies for increasing frequency efficiency include network MIMO, interference alignment, relay networks, heterogeneous networks, large-scale antennas, and distributed antenna systems.

The distributed antenna system separates the functions of the base station from the radio unit (RU) and the digital unit (DU), and divides the radio signal processor (ie, the antenna part or the transmission point) into a plurality and distributes them. Technology. In such a distributed antenna system, it is necessary for the digital signal processor to acquire channel state information in order to perform MIMO (Multi Input Multi Ouput) transmission through a plurality of wireless signal processors. In order to obtain the channel state information, a lot of reference signals and radio resources for channel state information feedback are required.

In addition, in a distributed antenna system, as the number of users that can be accommodated at the same time increases, there is a problem in that scheduling and precoding calculation complexity increases.

An object of the present invention is to provide a terminal, a base station, and an operation method of reducing feedback for channel state information in a distributed antenna system.

According to an embodiment of the present invention, a method of operating a terminal communicating with a base station including first and second transmission points located at different locations is provided. The operation method of the terminal may include receiving a reference signal for measuring a channel state from the base station, calculating a first value which is a ratio of a signal and a noise transmitted to the terminal using the reference signal, the reference signal Calculating a second value that is a ratio of interference and noise from the first transmission point, and calculating a third value that is a ratio of interference and noise from the second transmission point using the reference signal And feeding back information on the first to third values to the base station.

The base station may calculate channel state information for multiple transmission point MIMO using the first to third values.

The base station may perform scheduling for the multi-transmission point MIMO using the calculated channel state information.

The multi-transmission point MIMO may be a method in which data is transmitted to the terminal and other terminals other than the terminal with the same resource through the first and second transmission points.

The operating method of the terminal may include allocating the second value to a fourth value when the value obtained by dividing the second value by the first value is equal to or greater than a predetermined threshold, and assigning the third value to the fourth value. If the value divided by one value is smaller than the predetermined threshold, the method may further include allocating the third value to a fifth value, wherein the information on the second value corresponds to the fourth value. Information on the third value may correspond to the fifth value.

The fourth value and the fifth value may be one bit information.

The base station may be a small base station and the small base station may be wirelessly connected to the macro base station, and the small base station may be connected to a backhaul through the wireless and the macro base station.

The first transmission point and the second transmission point may be located in different buildings.

According to another embodiment of the present invention, there is provided a method of operating a base station including first and second wireless signal processing units distributed to each other and a digital processing unit connected to the first and second wireless signal processing units. The operating method of the base station may include transmitting a reference signal for measuring a channel state to a terminal, and receiving a first value, which is a ratio of a signal and a noise transmitted to the terminal, calculated using the reference signal, from the terminal. Receiving a second value from the terminal, the second value being a ratio of interference and noise by the first radio signal processor, calculated using the reference signal, and the second radio signal processor calculated using the reference signal. And receiving a third value, which is a ratio of interference and noise, from the terminal.

The operation method of the base station may further include calculating channel state information for multiple transmission point MIMO using the first to third values.

The operation method of the base station may further include performing scheduling for the multiple transmission point MIMO using the calculated channel state information.

The multi-transmission point MIMO may be a method in which the base station transmits data with the same resource to the terminal and other terminals other than the terminal through the first and second radio signal processing units.

The base station may be a small base station and the small base station may be wirelessly connected to the macro base station, and the small base station may be connected to a backhaul through the wireless and the macro base station.

According to another embodiment of the present invention, a terminal is provided for communicating with a base station including first and second transmission points that are distributed in different locations. The terminal uses the RF module to receive a reference signal for channel state measurement from the base station, and the reference signal, to the first value and the second transmission point which is a ratio of interference and noise by the first transmission point. And a processor for calculating a second value that is a ratio of interference and noise.

The processor may calculate a third value, which is a ratio of a signal and a noise transmitted to the terminal, using the reference signal.

The RF module may feed back information about the first to third values to the base station.

If the value obtained by dividing the first value by the third value is equal to or greater than a predetermined threshold, the processor allocates the first value to a fourth value and divides the second value by the third value. When the value is equal to or greater than the predetermined threshold, the second value may be assigned as the fifth value.

The RF module may feed back the third value, the fourth value, and the fifth value to the base station.

The fourth value and the fifth value may be 1 bit information.

According to the exemplary embodiment of the present invention, the feedback overhead may be reduced by feeding back only a predetermined interference signal strength rather than measuring and reporting channel state information from all transmission points.

1 is a diagram illustrating a wireless communication system according to an exemplary embodiment of the present invention.

2 is a diagram illustrating a small base station according to an embodiment of the present invention.

3 is a diagram illustrating an environment in which a plurality of wireless signal processing units of FIG. 2 are concentrated.

4 is a diagram illustrating interference and a signal in an MT-MIMO environment according to an embodiment of the present invention.

5 is a diagram illustrating a method of operating a terminal and a small base station in a distributed antenna system according to an exemplary embodiment of the present invention.

6 is a diagram illustrating a terminal according to an embodiment of the present invention.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

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

In addition, a base station (BS) may be an advanced base station (ABS), a 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 (RAS), base transceiver station (BTS), mobile multihop relay (MMR) -BS, relay serving as a base station station, RS), a high reliability relay (HR-RS) serving as a base station, etc., and may also refer to ABS, Node B, eNodeB, AP, RAS, BTS, MMR-BS, RS, HR. It may include all or part of functions such as -RS.

1 is a diagram illustrating a wireless communication system according to an exemplary embodiment of the present invention.

As shown in FIG. 1, a wireless communication system according to an embodiment of the present invention includes a macro base station 100 and a plurality of small base stations 200.

The macro base station 100 is connected to the backhaul (core network) by wire and wirelessly connected to the plurality of small base stations 200. The macro base station 100 provides a wireless backhaul link to the plurality of small base stations 200, and the plurality of small base stations 200 are wirelessly connected to the backhaul through the macro base station 100, respectively. Meanwhile, the macro base station 100 according to the embodiment of the present invention may include a large-scale antenna system.

The transmit antenna correlation exists in the channel between the macro base station 100 installed in the high building and the small base station 200 installed in the low building. The transmission antenna correlation may be expressed as an angle of departure (AoD) and an angular spread (AS). When the macro base station 100 beamforms the small base station 200 using the transmission antenna correlation, the macro base station 100 may transmit data while reducing energy loss. This is called a tunnel effect. In order to implement the tunnel effect, the small base station 200 needs to be implemented as a distributed antenna system (ie, a distributed receiving antenna array).

On the other hand, in order to increase the transmission efficiency of the wireless backhaul in the distributed antenna system of the small base station 200, it is necessary to install a distributed antenna at an optimal position through channel measurement. The channel between the macro base station 100 and the small base station 100 is a very slow fading channel and the transmission correlation matrix hardly changes. Accordingly, beamforming optimized by a fixed transmission correlation matrix is possible, and a combination of fixed beamforming (analog beamforming) and digital beamforming can reduce implementation complexity and cost of a large antenna system. Analog beamforming may vary semi-statically according to terminal distribution in day and night time zones.

According to the embodiment of the present invention, since the small base station 200 is wirelessly connected to the backhaul network (core network) through the macro base station 100, it is possible to reduce the cost of building a dedicated wired network.

As described above, the small base station 200 according to the embodiment of the present invention has a distributed antenna system (distributed antenna array), which will be described in detail with reference to FIG. 2.

2 is a diagram illustrating a small base station 200 according to an embodiment of the present invention.

As shown in FIG. 2, the small base station 200 according to the embodiment of the present invention includes a digital processor DU 210 and a plurality of radio signal processors RU 220.

The plurality of wireless signal processing units 220 may be separated from each other and disposed in different buildings. As shown in FIG. 2, three wireless signal processing units may be disposed in the building A, three wireless signal processing units may be disposed in the building B, and three wireless signal processing units may be disposed in the building C. On the other hand, the plurality of wireless signal processing unit 220 is connected to each other through a dedicated network. Meanwhile, the plurality of wireless signal processing units 220 may include a plurality of antennas, respectively.

The digital processor DU 210 corresponds to the rest of the base station function of the small base station 200 except for the antenna part. The digital processing unit DU 210 according to an embodiment of the present invention may select an optimal wireless signal processing unit according to an access link channel state with the terminal 300 from among the plurality of wireless signal processing units 200. That is, the digital processing unit DU 210 may turn on or off the operation of a specific antenna array (wireless signal processing unit) according to the distribution or channel state of the terminal 300. Through the optimal transmission point (that is, the wireless signal processor) using the reconfigurable distributed antenna as described above, cooperative MIMO transmission is possible, and the terminal 300 can transmit and receive at a high transmission rate. This cooperative MIMO transmission is similar to MU-MIMO (Multi User-MIMO), which has multiple transmission points and multiple reception points (terminals). However, since the transmission points are located at different locations, hereinafter, Multi Transmitter MIMO (MT-) is used. MIMO). That is, in MT-MIMO, a plurality of radio signal processing units located at different locations transmit data to a plurality of terminals (ie, multi-users) using the same resources. Meanwhile, the digital processing unit DU transmits control information through downlink control information (DCI) so that each terminal recognizes a transmission point assigned to each terminal.

3 is a diagram illustrating an environment in which the plurality of wireless signal processors 220 of FIG. 2 are concentrated.

As shown in FIG. 3, the plurality of wireless signal processing units 220 are located at different locations, and service areas overlap each other. That is, cells serviced by the radio signal processing units 220 overlap each other and are densely packed. In the environment of FIG. 3, the cells are densely overlapped with each other, unlike typical cooperative transmissions in which the cells do not overlap each other. In such an environment in which cells overlap each other and are densely packed, signals transmitted by the plurality of wireless signal processing units 220 act as interference with each other. Hereinafter, a method of feeding back channel state information in a dense distributed antenna system environment as shown in FIG. 3 will be described.

Meanwhile, in the following description, the terms of the wireless signal processor 200 and a transmitter point (TX point) are used interchangeably. The transmission point corresponds to one wireless signal processing unit RU 220 in FIGS. 2 and 3, and each of the plurality of transmission points may include a plurality of antennas.

Conventionally, the UE directly measures and reports channel state information (CQI) for MU-MIMO. That is, conventionally, the terminal directly calculates CQI (Channel Quality Indication) for MU-MIMO and feeds it back to the small base station. However, in the embodiment of the present invention, the terminal does not directly calculate the CQI for MU-MIMO. In the embodiment of the present invention, the terminal feeds back only predetermined information (for example, MTI described below) so that the small base station 100 can estimate the CQI for the MT-MIMO. When there are a plurality of transmission points, the UE needs to know all transmission powers of the transmission points in order to calculate the CQI for MT-MIMO. However, since the positions of the transmission points are all different, it is impossible for the terminal to measure the CQI. In addition, the number of cases where the terminal calculates the CQI for MT-MIMO is too large, the feedback burden may increase. Therefore, in the embodiment of the present invention, the terminal feeds back only predetermined information (for example, MTI) described below. Meanwhile, non-zero power channel state information-reference signal (CSI-RS) and zero power CSI-RS are appropriately allocated among the multiple transmission points.

Hereinafter, a method of calculating a CQI for MT-MIMO according to an embodiment of the present invention will be described with reference to FIG. 4.

4 is a diagram illustrating interference and a signal in an MT-MIMO environment according to an embodiment of the present invention.

In FIG. 4, the transmission point Tx0 and the transmission point Tx1 are located at different locations, respectively, and correspond to the wireless signal processing unit 200 of FIG. 2. It is assumed that the transmission point TxO transmits data to the UE and transmits data using the same resources to other terminals (not shown) other than the UE. In addition, it is assumed that the transmission point Tx1 transmits data by using the same resource to another terminal other than the UE. In FIG. 4, it is assumed that two transmission points are provided for convenience. However, even if there are three or more transmission points, the embodiment of the present invention described below may be applied.

In FIG. 4, since the signal transmitted from the transmission point Tx0 to another terminal acts as an interference from the UE's point of view, this interference is represented by I b (0) . In addition, since the signal transmitted from the transmission point Tx1 to another terminal acts as an interference from the viewpoint of the terminal UE, such interference is represented as I c (1) . In addition, the signal transmitted by the transmission point Tx0 to the terminal UE is represented by S a (0) .

The CQI for MT-MIMO is called 'MT-CQI' for convenience. Here, since MT-CQI corresponds to a Signal Interference Noise Ratio (SINR) of the UE, the MT-CQI estimated by the small base station 200 is defined as Equation 1 below.

Equation 1

Figure PCTKR2015002882-appb-M000001

In Equation 1, N denotes the interference signal strength due to the background noise and other cells, and a constant 2 indicates that the power of the small base station 200 is divided by 1/2 and transmitted in two data streams. Subject to change. The superscript indicates the index of the transmission point and the subscript indicates the precoding matrix index (PMI).

As shown in Equation 1, the denominator represents the noise and interference signal strength experienced by the UE, and the numerator represents the strength of its signal received by the UE. Dividing both the numerator and denominator by N in Equation 1 results in Equation 2 below.

Equation 2

Figure PCTKR2015002882-appb-M000002

In Equation 2, INR represents an interference-to-noise ratio, which can be replaced by a multi-transmitter interference indicator (MTI) defined below. SNR a (0) represents a noise ratio of the self signal S a 0 of the UE and corresponds to a CQI used in a general LTE system. Therefore, finally, MT-CQI can be expressed as Equation 3 below.

Equation 3

Figure PCTKR2015002882-appb-M000003

Considering Equations 2 and 3, MTIs for efficient feedback may be defined as shown in Equation 4 below.

Equation 4

Figure PCTKR2015002882-appb-M000004

Figure PCTKR2015002882-appb-I000001

A UE according to an embodiment of the present invention calculates and transmits only information on CQI a (0) and MTI used in a general LTE system. In other words, the UE UE calculates S a 0 / N, which is a ratio of the noise N to the signal S a 0 transmitted thereto, and feeds it back to the small base station 200. The UE UE calculates I b (0) / N, which is the interference-to-noise ratio from the transmission point Tx0, and I c (1) / N, which is the interference-to-noise ratio from the transmission point Tx1, respectively. Feedback to 200. According to this embodiment of the present invention, the feedback overhead of the terminal can be reduced.

The small base station 200 finally calculates the MT-CQI according to Equation 3 using the CQI a (0) , the MTI b (0) , and the MTI b (1) fed back from the UE. Here, the calculation of the MT-CQI is performed by the digital processor 210 of the small base station 200. The digital processor 210 calculates the MT-CQI using the information CQI a (0) , MTI b (0) , and MTI b (1) fed back from the UE, thereby interfering with multiple transmission cores. The degree can be estimated. Through this, the digital processor 210 may perform scheduling and link adaptation for multiple users.

When the UE UE feeds back only MTI information regardless of the transmission power of another transmission point (for example, the transmission point Tx1), the small base station 200 (ie, the digital processing unit DU) 210 transmits all transmissions. The MT-CQI can be easily calculated because the transmit power per data stream of the point is known. That is, the small base station 200 knows the transmission power for each transmission point and can flexibly schedule it.

For example, suppose that the transmission point Tx1 transmits with equal power of 1/3 each using three PMIs c, d, and e. At this time, when the UE feeds back CQI a (0) MTI b (0) , MTI c (1) , MTI d (1) , and MTI e (1) , the small base station 200 transmits a transmission point (Tx1). Since the transmit power per data stream is known, MT-CQI can be calculated as shown in Equation 5 below.

Equation 5

Figure PCTKR2015002882-appb-M000005

Conventionally, since the terminal cannot know the power of other transmission points except for its own transmission point (ie, the transmission point of the terminal), it is difficult for the terminal to calculate the MT-CQI. As a result, the terminal could not receive multiple data streams from multiple transmission points. However, according to the embodiment of the present invention described above, the UE simply feeds back only the CQI and the MTI, and the base station knows the transmission power of each transmission point, so that the MT-CQI can be easily calculated.

Meanwhile, the MTI information fed back by the UE to the small base station 200 may reduce MIT overhead through the following method. The UE may simplify the MUI into 1-bit information through a ratio of the MTI and the SNR a (0) as shown in Equation 6 below with respect to a specific threshold value x.

Equation 6

Figure PCTKR2015002882-appb-M000006

Figure PCTKR2015002882-appb-I000002

As shown in Equation 6, when the ratio of the MTI and the SNR a (0 ) is equal to or smaller than the threshold value x, the terminal UE allocates '1' as the MTI information. When the ratio of MTI and SNR a (0) is larger than the threshold value x, the UE allocates '0' as MTI information. That is, the UE does not feed back a fine interference level, but feedbacks the interference beam having a very small interference level and an interference beam that does not. As such, since the MTI feedback information is reduced to 1 bit information, the MTI feedback overhead can be reduced.

On the other hand, this 1-bit information has a high probability of MUI of 1 in a channel having a large spatial correlation (or angular spread) and a very small number of '0's in all bits, so that a compression sensing technique is used. In this case, the feedback overhead can be further reduced.

5 is a diagram illustrating a method of operating a terminal and a small base station in a distributed antenna system according to an exemplary embodiment of the present invention.

First, the small base station 200 transmits a reference signal for measuring the channel state to the terminal (UE, 300) (S410). Here, the reference signal for measuring the channel state may be CSI-RS (Channel State Information-Reference Signal). Since the CSI-RS can be known to those skilled in the art, detailed description thereof will be omitted. The small base station 200 according to the embodiment of the present invention has a plurality of transmission points distributed as shown in FIG. 2, and CSI-RS signals are transmitted through the plurality of transmission points.

The UE (UE) 300 calculates CQI a (0) of Equation 3 using the reference signal received from the small base station 200 (S420). As described above, CQI a (0) is a noise ratio, that is, S a 0 / N for the signal S a 0 transmitted from the terminal 300 to itself.

In addition, the terminal UE 300 calculates an MTI of Equation 4 using the reference signal received from the small base station 200 (S430). That is, the terminal UE 300 calculates an MTI which is an interference-to-noise ratio for each transmission point (radio signal processing unit) of the small base station. In case of two transmission points, the UE UE 300 transmits MTI b (0) (I b (0) / N, which is the interference-to-noise ratio from the transmission point Tx0) and MTI b (0) (transmission ) Calculate I c (1) / N, which is the interference-to-noise ratio from point Tx1.

The UE (UE, 300) feeds back the CQI a (0) calculated in step S420 and the MTI calculated in step S430 to the small base station 200 (S440).

The small base station 200 calculates the MT-CQI as shown in Equation 3 by using the CQI a (0) and the MTI fed back from the terminal (UE) 300 (S450). That is, since the small base station 200 knows the power allocation information of each transmission point, the small base station 200 may calculate the MT-CQI by applying Equation 3 below.

The small base station 200 performs scheduling and link adaptation for a multi-user using the MT-CQI calculated in step S450 (S460). The small base station 200 may select a transmission point to transmit optimal data to multiple users among a plurality of transmission points through MT-CQI, and may select multiple users. Through this, interference mitigation between the transmission point and the terminal is possible.

6 is a diagram illustrating a terminal according to an embodiment of the present invention.

As shown in FIG. 6, the terminal 300 according to the embodiment of the present invention includes a processor 310, a memory 320, and an RF module 330.

The processor 310 may be configured to implement the procedures, methods, and functions described with reference to FIGS. 1 to 4.

The memory 320 is connected to the processor 310 and stores various information related to the operation of the processor 310.

The RF module 330 is connected to an antenna (not shown) and transmits or receives a radio signal. The antenna may be implemented as a single antenna or multiple antennas (MIMO antenna). 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 of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

The present invention can be used in a mobile communication system.

Claims (19)

  1. A method of operating a terminal communicating with a base station including first and second transmission points located at different locations,
    Receiving a reference signal for measuring a channel state from the base station,
    Calculating a first value which is a ratio of a signal and a noise transmitted to the terminal using the reference signal,
    Using the reference signal, calculating a second value that is a ratio of interference and noise from the first transmission point,
    Using the reference signal, calculating a third value that is a ratio of interference and noise from the second transmission point, and
    And feeding back information about the first to third values to the base station.
  2. The method of claim 1,
    The base station calculates channel state information for multiple transmission point MIMO using the first to third values.
  3. The method of claim 2,
    And the base station performs scheduling for the multi-transmission point MIMO using the calculated channel state information.
  4. The method of claim 2,
    The multi-transmission point MIMO is a method in which data is transmitted to the terminal and other terminals other than the terminal with the same resource through the first and second transmission points.
  5. The method of claim 1,
    Allocating the second value to a fourth value when the value obtained by dividing the second value by the first value is equal to or greater than a predetermined threshold value, and
    Allocating the third value to a fifth value when the value obtained by dividing the third value by the first value is less than the predetermined threshold value;
    The information on the second value corresponds to the fourth value, and the information on the third value corresponds to the fifth value.
  6. The method of claim 5,
    And the fourth value and the fifth value are one bit information.
  7. The method of claim 1,
    The base station is a small base station and the small base station is wirelessly connected to the macro base station, the small base station is connected to the backhaul through the wireless and the macro base station.
  8. The method of claim 1,
    And the first transmission point and the second transmission point are located in different buildings.
  9. A method of operating a base station including first and second wireless signal processing units distributed to each other and a digital processing unit connected to the first and second wireless signal processing units,
    Transmitting a reference signal for measuring a channel state to a terminal;
    Receiving a first value from the terminal, which is a ratio of a signal transmitted to the terminal and a noise, calculated using the reference signal,
    Receiving a second value from the terminal, which is a ratio of interference and noise by the first radio signal processor, calculated using the reference signal, and
    And receiving a third value, which is a ratio of interference and noise, by the second radio signal processing unit, calculated using the reference signal, from the terminal.
  10. The method of claim 9,
    Calculating channel state information for multiple transmission point MIMO using the first to third values.
  11. The method of claim 10,
    And performing scheduling for the multiple transmission point MIMO using the calculated channel state information.
  12. The method of claim 10,
    The multi-transmission point MIMO is a method of the base station is a method of transmitting data with the same resources to the terminal and the other terminal other than the terminal through the first and second radio signal processing unit.
  13. The method of claim 9,
    And wherein the base station is a small base station, the small base station is wirelessly connected to a macro base station, and the small base station is connected to a backhaul via the wireless and the macro base station.
  14. A terminal for communicating with a base station including first and second transmission points distributed in different places,
    An RF module for receiving a reference signal for measuring channel conditions from the base station, and
    And a processor configured to calculate a first value which is a ratio of interference and noise by the first transmission point and a second value which is a ratio of interference and noise by the second transmission point, using the reference signal.
  15. The method of claim 14,
    The processor calculates a third value, which is a ratio of a signal and a noise transmitted to the terminal, using the reference signal.
  16. The method of claim 15,
    The RF module is a terminal for feeding back information about the first value to the third value to the base station.
  17. The method of claim 14,
    The processor,
    If the value obtained by dividing the first value by the third value is equal to or greater than a predetermined threshold, the first value is assigned to a fourth value,
    And assigning the second value to a fifth value when the value obtained by dividing the second value by the third value is equal to or greater than a predetermined threshold.
  18. The method of claim 17,
    The RF module feeds back the third value, the fourth value and the fifth value to the base station.
  19. The method of claim 18,
    The fourth value and the fifth value are 1 bit information.
PCT/KR2015/002882 2014-03-25 2015-03-24 Terminal, base station, and operation method thereof in distributed antenna system WO2015147524A1 (en)

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KR20140154769 2014-11-07
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KR1020150040572A KR20150111310A (en) 2014-03-25 2015-03-24 Terminal and operation method thereof in distributed antenna system

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