KR20140123711A - Method and apparatus for processing transmitting signal of multiple antenna system - Google Patents

Method and apparatus for processing transmitting signal of multiple antenna system Download PDF

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Publication number
KR20140123711A
KR20140123711A KR1020130040869A KR20130040869A KR20140123711A KR 20140123711 A KR20140123711 A KR 20140123711A KR 1020130040869 A KR1020130040869 A KR 1020130040869A KR 20130040869 A KR20130040869 A KR 20130040869A KR 20140123711 A KR20140123711 A KR 20140123711A
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KR
South Korea
Prior art keywords
receiver
matrix
precoding
transmitter
inter
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KR1020130040869A
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Korean (ko)
Inventor
이승환
이준호
방승찬
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한국전자통신연구원
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Priority to KR1020130040869A priority Critical patent/KR20140123711A/en
Publication of KR20140123711A publication Critical patent/KR20140123711A/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/02—Transmitters
    • H04B1/04—Circuits
    • H04B1/0475—Circuits with means for limiting noise, interference or distortion
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity 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
    • H04B7/0615—Diversity 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
    • H04B7/0617—Diversity 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 for beam forming
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity 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
    • H04B7/0615—Diversity 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
    • H04B7/0619—Diversity 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
    • H04B7/0636—Feedback format
    • H04B7/0639—Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection

Abstract

The present invention relates to a method for processing a transmission signal with a transmitter using a multi-antenna which includes a step of forming a plurality of beams dividing a space in multiple units by using the multi-antenna; a step of determining whether there is a receiver having interference between beams; and a step of transmitting a signal in the direction of the beam of the receiver receiving data when the receiver having the interference between the beams does not exist.

Description

Field of the Invention [0001] The present invention relates to a multi-

The present invention relates to a method and apparatus for processing a multi-antenna transmission signal.

A base station uses various pre-coding methods that utilize channel information to remove inter-user interference in a multi-user environment. In particular, it has been shown that the Dirty Paper Coding (DPC) method can achieve sum channel capacity in a Gaussian broadcast multiple receiver multi-antenna channel.

Realistic methods in terms of complexity than DPC were invented as a way to reach the limit capacity. Zero-Forcing (ZF) and Minimum Mean Square Error (MMSE) were invented as linear precoding methods. The nonlinear precoding method Tomlinson-Harashima precoder (THP) method and various modified methods were invented.

However, conventional multi-antenna transmitters use a dense channel matrix to design the precoding matrix. Therefore, the conventional multi-antenna transmitter has high complexity. Although Maximal Ratio Transmission (MRT), which takes a Hermitian in a full channel matrix when the channel matrix is a large dimension, is considered, this method can not achieve the theoretical performance if an antenna close to infinity is used in the transmitter There is a limit.

An object of the present invention is to provide a transmission signal processing method of a multi-antenna transmitter for allowing a plurality of receivers to independently receive services without being influenced by each other's interference.

A method of processing a transmission signal using a multiple antenna according to an exemplary embodiment of the present invention includes the steps of forming a plurality of beams dividing a space into a plurality of beams using the multiple antennas, And transmitting the signal in the direction of the beam to which the receiver to receive the data belongs if there is no receiver experiencing inter-beam interference.

The transmission signal processing method may further include precoding data when there is a receiver experiencing inter-beam interference, and transmitting a precoded signal in the direction of the beam to which the receiver is to receive the data .

The precoding step may calculate a precoding matrix based on a channel matrix between the transmitter and the receiver according to beamforming, and precode the data using the precoding matrix.

The channel matrix may be a sparse-block diagonal matrix.

The channel matrix may be a matrix whose dimension is variable due to beam selection.

The pre-coding step may calculate the precoding matrix using an inverse matrix of the channel matrix.

Wherein the precoding step calculates the precoding matrix using an inverse of a channel matrix of a first receiver and a second receiver, the first receiver being a receiver subject to inter-beam interference, Lt; RTI ID = 0.0 > beam. ≪ / RTI >

In a transmitter including multiple antennas according to another embodiment of the present invention, if there is a receiver experiencing inter-beam interference among a plurality of beams formed using multiple antennas and there is a receiver experiencing inter-beam interference, And a precoding unit for precoding the data according to the determination of the control unit.

The controller may determine not to precode the data if there is no receiver experiencing inter-beam interference.

The transmitter forms a plurality of beams by dividing a space into a plurality of spaces by using the multiple antennas, selects a beam according to the determination of the controller, and transmits a signal that is not precoded or precoded by the precoding unit And the like.

The precoding unit may calculate a precoding matrix based on a channel matrix between the transmitter and the receiver according to the beamforming, and precode the data using the precoding matrix.

The channel matrix may be a sparse-block diagonal matrix.

The channel matrix may be a matrix whose dimension is variable due to beam selection.

The precoding unit may calculate the precoding matrix using an inverse matrix of the channel matrix.

Wherein the precoding unit computes the precoding matrix using an inverse of a channel matrix of a first receiver and a second receiver, the first receiver is a receiver subject to inter-beam interference, and the second receiver is a receiver It can be a receiver that belongs.

According to the embodiment of the present invention, beams can be formed using previously stored beam directions to distinguish receivers. According to the embodiment of the present invention, when there is no inter-beam interference, the beam in the receiver direction can be selected and data can be transmitted without precoding. Also, according to the embodiment of the present invention, since a precoding matrix of a sparse-block diagonal matrix structure is used even if there is a receiver experiencing inter-beam interference, inter-beam interference can be efficiently eliminated with a small calculation amount. According to the embodiment of the present invention, precoding is omitted or a precoding matrix with a small calculation amount is used, so that the complexity of the transmitter can be reduced.

1 is a diagram illustrating multiple beams of a multi-antenna transmitter according to an embodiment of the present invention.
2 is a view for explaining a signal processing method in a case where there is no inter-beam interference according to an embodiment of the present invention.
3 is a view for explaining a signal processing method in a case where there is inter-beam interference according to another embodiment of the present invention.
4 is a flowchart illustrating a method of processing a multi-antenna transmission signal according to an embodiment of the present invention.
5 is a block diagram of a transmitter in accordance with 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 receiver may be referred to as a mobile terminal (MT), a mobile station (MS), a subscriber station (SS), a portable subscriber station (PSS) AT), user equipment (UE), and the like, and may include all or some of the functions of MT, MS, SS, PSS, AT, UE,

In addition, the transmitter includes a base station (BS), a node B, an evolved Node B (eNodeB), an access point (AP), a radio access station (RAS) May refer to a base transceiver station (BTS), a mobile multihop relay (MMR) -BS, etc., and may include all or some of the functions of a Node B, an eNodeB, an AP, a RAS, a BTS, have.

Throughout the specification, when an element is referred to as "comprising ", it means that it can include other elements as well, without excluding other elements unless specifically stated otherwise. Also, the terms " part, "" module," " module, "and " block" refer to units that process at least one function or operation, Lt; / RTI >

1 is a diagram illustrating multiple beams of a multi-antenna transmitter according to an embodiment of the present invention.

Referring to FIG. 1, the transmitter 100 uses N multiple antennas, and forms a beam dividing a space into N parts. The multi-antenna transmitter 100 forms a channel close to the Line Of Sight (LOS) environment by high frequencies. At this time, it is assumed that there may be interference between adjacent beams.

The transmitter 100 forms a beam in advance to primarily divide receivers into a space. If the transmitter 100 can classify all receivers into preformed beams, it does not precode and selects the beam in the receiver direction and transmits the signal.

If a receiver experiences inter-beam interference, the transmitter 100 transmits the precoded signal toward the receiver. Precoding is a method of eliminating interference by pre-processing transmission data based on channel information.

The transmitter 100 multiplies transmission data by a precoding matrix to generate a transmission signal. At this time, since the transmitter 100 has spatially separated the beam, the actual channel matrix between the transmitter 100 and the receivers is represented by a special structure, a sparse-block diagonal matrix. Therefore, the transmitter 100 uses the channel matrix corresponding to the selected beam instead of precoding using a dense channel matrix as in the prior art, thereby effectively eliminating the inter-beam interference with a small amount of calculation.

2 is a view for explaining a signal processing method in a case where there is no inter-beam interference according to an embodiment of the present invention.

Referring to FIG. 2, the transmitter 100 forms N beams using multiple antennas. The transmitter 100 calculates and stores a beamforming matrix of multiple antennas. When the transmitter 100 uses a multi-directional antenna, the beamforming matrix is a unitary matrix.

The transmitter 100 communicates with the K receivers 200-1, 200-2, ..., 200-K. The transmitter 100 determines whether the K receivers are subject to inter-beam interference.

In the absence of a receiver experiencing inter-beam interference, the transmitter 100 selects the beam to which the receiver belongs and transmits the signal in the direction of the selected beam. At this time, the transmitter 100 does not perform precoding. In other words, there is no interference between beams, so precoding is not required.

The signal received by the receiver (

Figure pat00001
) ≪ / RTI > In the absence of inter-beam interference, the actual channel matrix between the transmitter 100 and the receivers (
Figure pat00002
) Has a special structure, that is, a diagonal matrix structure. The actual channel matrix by the prior beamforming is Wyner modeled. And, if the number of receivers is less than the number of beams, the actual channel matrix becomes a matrix of small dimensions due to beam selection.

Figure pat00003

In Equation (1)

Figure pat00004
, ≪ / RTI > is the received vector of the K receivers,
Figure pat00005
Is the received value of the kth receiver.
Figure pat00006
Is the channel matrix between the transmitter 100 and the receivers by pre-beam forming and beam selection.
Figure pat00007
Is the channel vector between the transmitter multiple antennas and the kth receiver.
Figure pat00008
Is the beam forming vector in the kth receiver direction.
Figure pat00009
Is information that the transmitter 100 transmits to the K receivers,
Figure pat00010
Is the transmission value to the kth receiver.
Figure pat00011
Is the noise vector of the K receivers.

3 is a view for explaining a signal processing method in a case where there is inter-beam interference according to another embodiment of the present invention.

Referring to FIG. 3, the transmitter 100 forms N beams using multiple antennas. The transmitter 100 calculates and stores a beamforming matrix of multiple antennas. When the transmitter 100 uses a multi-directional antenna, the beamforming matrix is a unitary matrix.

The transmitter 100 communicates with the K receivers 300-1, 300-2, ..., 300-K.

The transmitter 100 determines whether the K receivers are subject to inter-beam interference. For example, if there is a receiver 300-2 experiencing interference between a first beam and a second beam, the transmitter 100 performs precoding to remove inter-beam interference. Then, the transmitter 100 transmits a precoded signal in the direction of the selected beam. At this time, the transmitter 100 precodes using a special structure of a substantial channel matrix between the transmitter and the receiver, i.e., a sparse-block diagonal matrix. There are a variety of precoding methods, such as Zero-Forcing (ZF), Minimum Mean Square Error (MMSE), Tomlinson-Harashima precoder (THP)

Among various precoding methods, the ZF precoding method will be described as an example.

The ZF precoding method designs the precoder using the inverse of the channel between the transmitter and the receiver. The channel matrix between the transmitter and the receiver (

Figure pat00012
) Has a structure of a sparse-block diagonal matrix by beam forming as shown in Equation (2). If the number of receivers is less than the number of beams, the channel matrix is reduced to a square matrix of small dimensions as many as the number of receivers.

Figure pat00013

The rare-block diagonal matrix of Equation (2)

Figure pat00014
) And a sub-matrix (
Figure pat00015
). Sub matrix (
Figure pat00016
Is a channel information of a receiver that is interfered with a beam interfering with a beam that interferes with a beam, and is a triangular matrix as shown in Equation (3). Sub matrix (
Figure pat00017
) Is a beamforming matrix, which is a diagonal matrix as shown in Equation (4).

Figure pat00018

Figure pat00019

Inverse matrix of channel matrix (

Figure pat00020
) Is calculated as an inverse matrix of each sub-matrix, as shown in Equation (5).

Figure pat00021

Since precoding is performed for eliminating inter-beam interference, a precoding matrix (

Figure pat00022
) Is a triangular matrix < RTI ID = 0.0 > (
Figure pat00023
) ≪ / RTI > That is, the transmitter 100 includes a beamforming matrix (
Figure pat00024
). Therefore, the transmitter 100 transmits the channel information of the receiver belonging to the beam that interferes with the receiver receiving the inter-beam interference (
Figure pat00025
), The precoding matrix (
Figure pat00026
) Can easily be calculated.

Figure pat00027

4 is a flowchart illustrating a method of processing a multi-antenna transmission signal according to an embodiment of the present invention.

Referring to FIG. 4, the transmitter 100 forms a plurality of beams using multiple antennas (S110).

The transmitter 100 selects the beam where the receivers are located (S120).

The transmitter 100 determines whether there is a receiver that experiences inter-beam interference in a plurality of beams (S130). The transmitter 100 may determine interference based on the channel information received from the receivers.

If there is no receiver experiencing inter-beam interference, the transmitter 100 transmits a signal in the direction of the beam to which the receiver is to transmit the data (S140).

If there is a receiver experiencing inter-beam interference, the transmitter 100 precodes the transmission data to eliminate inter-beam interference (S150). At this time, the transmitter 100 precodes using a special structure of a substantial channel matrix between the transmitter and the receiver, i.e., a sparse-block diagonal matrix. When the ZF precoding method is used, the transmitter 100 calculates a precoding matrix using an inverse matrix of the channel matrix, and precodes the data based on the precoding matrix. The transmitter 100 can calculate the precoding matrix by calculating only the inverse of the channel of the receiver belonging to the beam interfering with the receiver receiving the inter-beam interference.

Then, the transmitter 100 transmits a precoded signal in the direction of the beam where the receiver for transmitting the data is located (S160).

5 is a block diagram of a transmitter in accordance with an embodiment of the present invention.

Referring to FIG. 5, the transmitter 100 includes a transceiver 110, a controller 130, and a precoding unit 150.

Under the control of the control unit 130, the transmitting and receiving unit 110 forms beams for dividing a space into N by using multiple antennas. At this time, each beam forms a channel close to the line of sight (LOS) environment. There may be interference between adjacent beams. Under the control of the control unit 130, the transmission / reception unit 110 selects a beam to which a receiver to receive data belongs, and transmits a signal to the selected beam. The transmission / reception unit 110 receives various kinds of information from receivers.

The control unit 130 determines whether there is a receiver experiencing inter-beam interference based on the information received from the transmitter-receiver unit 110. In the absence of a receiver experiencing inter-beam interference, the controller 130 selects the beam to which the receiver belongs and requests the transceiver 110 to transmit the signal in the direction of the selected beam. If there is a receiver experiencing inter-beam interference, the controller 130 transfers the data to the precoding unit 150. [

The precoding unit 150 estimates the actual channel matrix between the transmitter 100 and the receivers

Figure pat00028
). The actual channel matrix between the transmitter 100 and the receivers (
Figure pat00029
) Has a special structure, that is, a diagonal matrix structure. Also, if the number of receivers is less than the number of beams, the channel matrix is reduced to a square matrix of small dimensions as many as the number of receivers. Accordingly, the precoding unit 150 may include a channel matrix
Figure pat00030
) Can be used to simply calculate the precoding matrix. The precoding unit 150 transmits the precoded signal to the transceiving unit 110.

As described above, according to the embodiment of the present invention, it is possible to distinguish receivers by forming a beam using a previously stored beam direction. According to the embodiment of the present invention, when there is no inter-beam interference, the beam in the receiver direction can be selected and data can be transmitted without precoding. Also, according to the embodiment of the present invention, since a precoding matrix of a sparse-block diagonal matrix structure is used even if there is a receiver experiencing inter-beam interference, inter-beam interference can be efficiently eliminated with a small calculation amount. According to the embodiment of the present invention, precoding is omitted or a precoding matrix with a small calculation amount is used, so that the complexity of the transmitter can be reduced.

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 (15)

CLAIMS What is claimed is: 1. A method of processing a transmission signal by a transmitter using multiple antennas,
Forming a plurality of beams dividing a space into a plurality of beams using the multiple antennas;
Determining if there is a receiver experiencing inter-beam interference, and
If there is no receiver experiencing inter-beam interference, transmitting a signal in the direction of the beam to which the receiver to receive the data belongs
And transmitting the transmission signal. The method of claim 1,
If there is a receiver experiencing inter-beam interference, precoding the data, and
Transmitting a precoded signal in a direction of a beam to which the receiver for receiving the data belongs
And transmitting the transmission signal. 3. The method of claim 2,
The precoding step
Calculating a precoding matrix based on a channel matrix between the transmitter and the receiver in accordance with the beamforming, and precoding the data using the precoding matrix. 4. The method of claim 3,
Wherein the channel matrix is a sparse-block diagonal matrix. 4. The method of claim 3,
Wherein the channel matrix is a matrix whose dimensions are variable due to beam selection. 4. The method of claim 3,
The precoding step
And calculating the precoding matrix using an inverse matrix of the channel matrix. The method of claim 6,
The precoding step
Calculating a precoding matrix using an inverse of a channel matrix of a first receiver and a second receiver, wherein the first receiver is a receiver subject to inter-beam interference and the second receiver is a receiver belonging to an interference- A method for processing a transmission signal. A transmitter comprising multiple antennas,
Determining whether there is a receiver experiencing inter-beam interference among a plurality of beams formed using multiple antennas, and, if there is a receiver experiencing inter-beam interference, deciding to precode the data; and
A pre-coding unit for pre-coding data according to the determination of the control unit,
≪ / RTI > 9. The method of claim 8,
The control unit
A transmitter that decides not to precode data if there is no receiver experiencing inter-beam interference. The method of claim 9,
A plurality of beams for dividing a space into a plurality of beams by using the multiple antennas, a transmitter for selecting beams according to the determination of the controller, and transmitting signals not precoded or precoded by the precoding unit,
≪ / RTI > 9. The method of claim 8,
The precoding unit
Calculating a precoding matrix based on a channel matrix between the transmitter and the receiver in accordance with the beamforming, and precoding the data using the precoding matrix. 12. The method of claim 11,
Wherein the channel matrix is a sparse-block diagonal matrix. 12. The method of claim 11,
Wherein the channel matrix is a matrix whose dimensions are variable due to beam selection. 12. The method of claim 11,
The precoding unit
And calculating the precoding matrix using an inverse matrix of the channel matrix. The method of claim 14,
The precoding unit
Calculating a precoding matrix using an inverse of a channel matrix of a first receiver and a second receiver, wherein the first receiver is a receiver subject to inter-beam interference and the second receiver is a receiver belonging to an interference- , Transmitter.
KR1020130040869A 2013-04-15 2013-04-15 Method and apparatus for processing transmitting signal of multiple antenna system KR20140123711A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9872277B2 (en) 2014-12-30 2018-01-16 Electronics And Telecommunications Research Institute Beam selection apparatus and method for selecting beam in a fixed beam terminal

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9872277B2 (en) 2014-12-30 2018-01-16 Electronics And Telecommunications Research Institute Beam selection apparatus and method for selecting beam in a fixed beam terminal

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