KR20160046243A - Transmitting apparatus and method for calibration and beamforming thereof, and method for receiving of receiving apparatus - Google Patents

Transmitting apparatus and method for calibration and beamforming thereof, and method for receiving of receiving apparatus Download PDF

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Publication number
KR20160046243A
KR20160046243A KR1020140142054A KR20140142054A KR20160046243A KR 20160046243 A KR20160046243 A KR 20160046243A KR 1020140142054 A KR1020140142054 A KR 1020140142054A KR 20140142054 A KR20140142054 A KR 20140142054A KR 20160046243 A KR20160046243 A KR 20160046243A
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South Korea
Prior art keywords
link
channel gain
receiving
sounding signal
signal
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KR1020140142054A
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Korean (ko)
Inventor
원석호
홍승은
김일규
방승찬
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한국전자통신연구원
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B17/00—Monitoring; Testing
    • H04B17/30—Monitoring; Testing of propagation channels
    • H04B17/373—Predicting channel quality or other radio frequency [RF] parameters
    • 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
    • H04B7/0686—Hybrid systems, i.e. switching and simultaneous transmission
    • H04B7/0695—Hybrid systems, i.e. switching and simultaneous transmission using beam selection
    • 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
    • H04B7/0413—MIMO systems
    • H04B7/0417—Feedback systems

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Quality & Reliability (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Radio Transmission System (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

When the transmitting apparatus receives the first sound signal after receiving the first signal multiplied by the total channel gain of the first link from the transmitting apparatus to the receiving apparatus to the first sounding signal from the receiving apparatus, Calculating a total channel gain of the second link and a total channel gain of the first link from the receiving apparatus to the transmitting apparatus using the sounding signal and calculating an overall channel gain of the first link and a total channel gain of the second link And calibrates the data to be transmitted for each antenna using the calibration coefficient.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmitting apparatus, a calibration method thereof, a beam forming method, and a receiving method of the receiving apparatus. BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission apparatus, a calibration method thereof, a beam forming method, and a receiving method of the receiving apparatus, and more particularly, to a calibration and beam forming method in a millimeter-band wireless communication system.

Wireless communication systems provide a variety of content such as voice, video, packet data, messaging, broadcast, and the like. These wireless communication systems may be multiple access systems capable of supporting multiple users by sharing available system resources.

A wireless communication system may include a plurality of base stations capable of supporting communication for a plurality of user equipments (hereinafter referred to as "terminals"). A base station can communicate with a terminal through a downlink and an uplink. The forward link refers to the communication link from the base station to the terminal including the repeater, and the communication link of the terminal in the repeater is also referred to as the forward link. On the other hand, the reverse link refers to the communication link from the terminal to the base station including the repeater, and the communication link from the repeater to the base station is also referred to as the reverse link.

The information needs to be packetized or converted into a message format, and each of the base station, the repeater, and the terminal may use a plurality of antennas in the transmission antennas and the reception antennas. That is, each of the base station, the repeater, and the terminal uses a plurality of antennas to transmit or receive good data to the wireless communication link, and this technique is referred to as a beam-forming technique. Methods and procedures for reducing beamforming degradation due to mismatch between antenna paths in such beam forming techniques are referred to as calibration.

The calibration for beamforming can be roughly divided into a calibration method using additional hardware and a method using only the original hardware for communication without additional hardware. In the case of using only the original hardware for communication without additional hardware, self-calibration (self-calibration) performing loop-back calibration in its own transmitting / receiving antenna and relative system (base station in case of base station, And over-the-air (OTA) -calibration, which performs calibration through actual wireless channels.

The calibration method using additional hardware is fundamentally necessary because of additional hardware, so that the unit price can not be put into practical use.

The self-calibration technique can cause problems due to frequent changes of impedance mismatches in the high frequency and millimeter band frequencies, and due to the radio interval interference, the calibration can not be accurately calibrated. It can not be used for FDD (Frequency Division Duplex) and can not be used for directional beamforming even in the case of TDD (Time Division Duplex).

On the other hand, the OTA-Calibration method proposed by Qualcomm, Intel and Alcatel-Lucent is a method that can perform calibration in a relatively accurate and convenient way, The overall gain including the gain of the wireless communication channel and the RF analog signal path gain must be received again in the form of a message or packet. For example, in order to calibrate at the base station, the terminal must inform the base station of the measured forward channel gain in the form of a message or a packet. The relative system must perform a conversion process of packet or message type in order to transmit the channel gain, so that it can be a large burden.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a transmitting apparatus capable of transmitting information necessary for OTA calibration in a simplest form without transmitting it in the form of a packet or a message, and a method of calibrating and beam forming the receiving apparatus.

According to an embodiment of the present invention, a calibration and beam forming method in a transmitting apparatus is provided. The calibration and beam forming method includes receiving a first signal multiplied by a total channel gain of a first link from the transmitting device to the receiving device to a first sounding signal from a receiving device, Calculating a reciprocating channel gain of a first link and a second link from the receiving apparatus to the transmitting apparatus, receiving the first sounding signal from the receiving apparatus, Predicting a total channel gain of the first link, estimating a total channel gain of the first link using the reciprocating channel gain and the total channel gain of the second link, Calculating a calibration coefficient using the overall channel gain of the second link, And correcting the error.

Wherein the step of calibrating comprises receiving the first sounding signal from the receiving device, predicting the overall channel gain of the second link using the first sounding signal, estimating the total channel gain of the second link And calculating the channel compensation weight value using the calibration coefficient, and multiplying the data to be transmitted for each antenna by the channel compensation weight value.

Wherein the receiving of the first signal comprises transmitting a second sounding signal to the receiving device, wherein the first link channel gain is predicted using the second sounding signal received by the receiving device, .

The first link is a forward link and the second link is a reverse link when the transmitting apparatus is a base station and the receiving apparatus is a terminal and the first link is a reverse link when the transmitting apparatus is a terminal and the receiving apparatus is a base station And the second link may be a forward link.

The overall channel gains of the first and second links may include transmit and receive RF chain path gains and radio channel gains, respectively.

According to another embodiment of the present invention, a method of receiving a beamformed signal from a transmitting apparatus in a receiving apparatus is provided. The receiving method includes receiving a first sounding signal from the transmitting device, estimating an overall channel gain of the first link from the transmitting device to the receiving device using the first sounding signal, Transmitting a first signal obtained by multiplying the first signal by a total channel gain of the first link to the transmitting device, transmitting the second sounding signal, and using the first signal and the second sounding signal And receiving calibration data for each antenna using the calibration coefficient from the transmission apparatus that has calculated the calibration coefficient.

Wherein the calibration coefficient is calculated by using the total channel gain of the second link from the receiving apparatus to the transmitting apparatus calculated using the second sounding signal and the total channel gain of the second link calculated from the first link and the second link, Lt; RTI ID = 0.0 > channel gain < / RTI >

The first link is a forward link and the second link is a reverse link when the transmitting apparatus is a base station and the receiving apparatus is a terminal and the first link is a reverse link when the transmitting apparatus is a terminal and the receiving apparatus is a base station And the second link may be a forward link.

According to another embodiment of the present invention, a transmitting apparatus for performing beam forming is provided. The transmitting apparatus includes a receiving unit, a gain calculating unit, a calibration calculating unit, a beam forming unit, and a transmitting unit. The receiver receives the first sounding signal after receiving the first signal multiplied by the overall channel gain of the first link from the transmitter to the receiver to the first sounding signal from the receiver. The gain calculator calculates the total channel gain of the first link and the total channel gain of the second link from the receiver to the transmitter using the first signal and the first sounding signal. The calibration calculation unit calculates a calibration coefficient using the total channel gain of the first link and the total channel gain of the second link. The beamformer corrects data to be transmitted for each antenna by using the calibration coefficient. The transmitter transmits the corrected data for each antenna.

Wherein the gain calculator calculates a reciprocating channel gain of the first link and the second link using the first signal, calculates an overall channel gain of the second link using the first sounding signal, The calibration coefficient may be calculated using the total channel gain of the first link and the total channel gain of the second link.

Wherein the receiving unit receives the third sounding signal from the receiving apparatus, the gain calculating unit calculates the overall channel gain of the second link using the third sounding signal, and the beam- The channel compensation weight value may be calculated using the total channel gain of the second link calculated using the signal and the calibration coefficient, and then the channel compensation weight value may be multiplied by the data to be transmitted for each antenna.

According to an embodiment of the present invention, a channel gain and a round-trip channel gain are measured from a signal transmitted from a transmitting apparatus (e.g., a base station) to be calibrated to a counterpart receiving apparatus (e.g., a terminal) So that the UE does not need to measure the forward channel gain and transmit the measured forward channel gain in the form of a packet or a message. Therefore, since the base station does not need to convert the packet format or the message format, the processing speed of the base station can be improved. In addition, since it is basically an OTA-calibration method, no additional hardware is required for calibration.

It may also be more effective than other methods when the effects of impedance mismatch between antennas, switches, and other RF components in the millimeter band are severely impacted.

1 is a flowchart illustrating a calibration and beam forming method according to an embodiment of the present invention.
2 is a flow chart illustrating a method for calculating calibration coefficients according to an embodiment of the present invention.
3 is a flowchart illustrating a method of compensating for asymmetry between transmission and reception RF chains according to an embodiment of the present invention.
4 is a diagram illustrating an example of a communication system having multiple antennas according to an embodiment of the present invention.
5 is a diagram illustrating a transmitting apparatus according to an embodiment of the present invention.

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

Throughout the specification and claims, when a section is referred to as "including " an element, it is understood that it does not exclude other elements, but may include other elements, unless specifically stated otherwise.

Throughout the specification, a terminal may be referred to as a user equipment (UE), 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) , AMS, HR-MS, SS, PSS, AT, and the like.

Also, a base station (BS) includes a node B, an evolved node B, an advanced base station (ABS), a high reliability base station (HR-BS) ENB, BS, ABS, HR-BS, etc.), an access point (AP), a radio access station (RAS), a base transceiver station AP, RAS, BTS, and the like.

Now, a transmitting apparatus, a calibration method, a beam forming method, and a receiving method of a receiving apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. Beamforming can be used for both forward and reverse links in a communication system using multiple transmit and receive antennas and the beamforming process of the forward link and the reverse link is the same, .

1 is a flowchart illustrating a calibration and beam forming method according to an embodiment of the present invention.

Referring to FIG. 1, the base station calculates a calibration coefficient for beamforming of the forward link using Over-The-Air (OTA) -calibration (S110). The calibration coefficient can be calculated as shown in Equation (1).

Figure pat00001

In Equation (1), h d is the total channel gain of the forward link, h u is the predicted value of the total channel gain of the reverse link, and c is the calibration coefficient. h d is obtained in a step S222 to be described later with reference to Fig. 2, and h u can be obtained in a step S220 described later with reference to Fig.

The base station calculates a channel compensation weight value to compensate for the asymmetry between the RF analog paths of the transmitting and receiving antennas using the calculated calibration coefficients (S120).

The base station multiplies the data to be transmitted by the channel compensation weight value to form a beam corresponding to the transmission antenna (S130), and transmits the beam of the transmission antenna (S140). At this time, the transmission antenna may be at least one transmission antenna.

Next, a method of calculating the calibration coefficient will be described in detail with reference to FIG. Calibration is a procedure for multiple antennas, but for the sake of clarity of operation, we will first refer to individual antennas.

2 is a flow chart illustrating a method for calculating calibration coefficients according to an embodiment of the present invention.

2, the base station 100 transmits a forward sounding signal

Figure pat00002
And a forward sounding signal
Figure pat00003
To the terminal 200 (S202). The forward sounding signal generated at the base station 100
Figure pat00004
Is transmitted to the terminal 200 via the forward link.

The terminal 200 receives a forward sounding signal

Figure pat00005
(S204).

The forward sounding signal generated at the base station 100

Figure pat00006
Is transmitted to the terminal 200 through the transmission RF chain path of the base station 100 and the wireless channel in the air and is received through the reception RF chain path of the terminal 200. [ In other words, the forward link includes a transmission RF chain path of the base station 100, a radio channel in the air, and a reception RF chain path of the terminal 200. At this time, it is assumed that the change of the channel is negligible. Accordingly, the forward sounding signal received from the terminal 200
Figure pat00007
Can be expressed by Equation (2).

Figure pat00008

In Equation 1 h d denotes a wireless channel gain of the forward link, α S is the base station 100 Represents the transmitted RF chain path gain, and [beta] A represents the received RF chain path gain of the terminal 200. [

Here, it is assumed that the interval of the RF chain is different depending on the forward link and the reverse link due to the characteristics of the RF elements. That is, the transmission RF chain path gains of the base station 100 and the base station 100 are different from each other, and the transmission RF chain path gains of the terminal 200 and the terminal 200 are different from each other. It is also assumed that the pure radio channel gains of the forward link without the RF analog path gain and the pure radio channel gains of the reverse link are the same for TDD and different for FDD.

The received signal of Equation (2) can be expressed as Equation (3).

Figure pat00009

In Equation 3,

Figure pat00010
Complex number
Figure pat00011
Quot; complex conjugate " complex number of < / RTI > The complex conjugate complex number is a sounding signal, and is a pilot signal which is mutually predetermined in the base station 100 and the terminal 200, respectively.

The terminal 200 predicts the overall channel gain of the forward link using Equation (3) (S206). Total channel gain estimate of the forward link

Figure pat00012
Can be calculated as shown in Equation (4).

Figure pat00013

The terminal 200 receives the reverse sounding signal < RTI ID = 0.0 >

Figure pat00014
And then calculates the total channel gain prediction value of the forward link
Figure pat00015
Lt; RTI ID = 0.0 >
Figure pat00016
And transmits it to the base station 100 through the reverse link (S208).

The base station 100 receives the estimated total channel gain of the forward link from the terminal 200

Figure pat00017
The multiplied backward sounding signal
Figure pat00018
(S210).

In the terminal 200, the total channel gain prediction value of the forward link

Figure pat00019
The multiplied backward sounding signal
Figure pat00020
Is transmitted to the base station 100 through the transmission RF chain path of the terminal 200 and the wireless channel in the air and is received through the reception RF chain path of the base station 100. That is, the reverse link includes a transmission RF chain path of the terminal 200, a radio channel in the air, and a reception RF chain path of the base station 100. Therefore, the reverse sounding signal received from the base station 100
Figure pat00021
Can be expressed by Equation (5).

Figure pat00022

In Equation (5), h u represents the radio channel gain of the reverse link, and β S represents the gain of the base station 100 Represents the received RF chain path gain, and [alpha] A represents the transmitted RF chain path gain of the terminal 200. [

The received signal of Equation (5) can be expressed as Equation (6). In Equation (6)

Figure pat00023
Is a sounding signal, and is a pilot signal that is promised between the base station 100 and the terminal 200 in advance.

Figure pat00024

The base station 100 calculates the round-trip channel gain of the forward link and the reverse link as shown in Equation (7)

Figure pat00025
(S212).

Figure pat00026

The base station 100 calculates the round-

Figure pat00027
Is stored in the buffer (S214).

The terminal 200 estimates the total channel gain estimate of the forward link

Figure pat00028
The multiplied backward sounding signal
Figure pat00029
To the base station 100, and then transmits a reverse sounding signal
Figure pat00030
To the base station 100 (S216).

The base station 100 receives a backward sounding signal from the terminal 200 (S218). As described above, the reverse sounding signal received at the base station 100

Figure pat00031
Can be expressed by Equation (8).

Figure pat00032

The received signal of Equation (8) can be expressed as Equation (9). In Equation (9)

Figure pat00033
Is a sounding signal, and it is assumed that the base station 100 and the terminal 200 are pilot signals that are promised mutually.

Figure pat00034

The base station 100 predicts the overall channel gain of the reverse link using Equation (9) (S220). Total channel gain estimate for the reverse link

Figure pat00035
Can be calculated as shown in Equation (10).

Figure pat00036

The base station 100 calculates the total channel gain prediction value of the forward link based on Equation (11)

Figure pat00037
(S222).

Figure pat00038

The base station 100 calculates the calibration coefficient c from the relationship of the equation (12) (S224).

Figure pat00039

Here, the radio channel gain h d of the forward link and the radio channel gain h u of the reverse link change in time in milliliter seconds, and the RF chain path gains α and β are relatively long .

The base station 100 compensates for the asymmetry between the transmitting and receiving RF chains using the calibration coefficient c.

3 is a flowchart illustrating a method of compensating for asymmetry between transmission and reception RF chains according to an embodiment of the present invention. Hereinafter, the MRT (Maximal Ratio Transmission) technique will be described as an example for convenience of explanation, and the present invention can be applied to other beam forming techniques of multiple antennas. Here, the operation of the individual antenna will be described as a reference.

Referring to FIG. 3, the terminal 200 transmits a sounding signal

Figure pat00040
To the base station (100).

The base station 100 receives a backward sounding signal from the terminal 200 (S302). As described above, the base station 100 uses the received reverse direction sounding signal to transmit a reverse link signal including the transmission RF chain path gain of the terminal 200, the radio channel gain of the reverse link, and the reception RF chain path gain of the base station 100, Overall channel gain of

Figure pat00041
(S304).

Next, the base station 100 determines the total channel gain of the reverse link

Figure pat00042
And a calibration coefficient c are used to calculate a channel compensation weight value (S306). Channel compensation weight value
Figure pat00043
Can be calculated as shown in Equation (13).

Figure pat00044

The base station 100 includes a channel compensation weight value

Figure pat00045
To the terminal 200 (S308).

The data received from the terminal 200

Figure pat00046
Can be expressed by Equation (14).

Figure pat00047

At this time, from the definition of the calibration coefficient c,

Figure pat00048
Can be expressed by Equation (15).

Figure pat00049

Therefore,

Figure pat00050
&Quot; (16) "

Figure pat00051

Where k is a constant scalar value.

As described above, the base station 100 compensates the entire channel gain of the forward link in advance using the calibration coefficient.

Although calibration and beam formation of individual antennas have been described above, calibration and beam formation will be described below by extending to multiple transmission / reception antennas. To facilitate understanding of the operation, the system of FIG. 4 is assumed.

4 is a diagram illustrating an example of a communication system having multiple antennas according to an embodiment of the present invention.

Referring to FIG. 4, the communication system includes a base station 100 and a terminal 200. The base station 100 and the terminal 200 each include multiple antennas. For example, the base station 100 may include two antennas, and the terminal 200 may include three antennas.

The following equations are examples of channel estimation using a sounding signal, and various channel estimation methods can be applied. For example, a Hermitian matrix is used for channel estimation, and channel estimation can be performed using an inverse determinant. The channel estimation method used in the embodiment of the present invention is not limited to the specific method.

The radio channel gain H d of the forward link and the radio channel gain H u of the reverse link can be expressed by Equations 17 and 18.

Figure pat00052

Figure pat00053

Here, h ij denotes a wireless channel, i denotes an antenna of the terminal 200, and j denotes an antenna of the base station 100. 6, three antennas of the terminal 200 and two antennas of the base station 100, i is represented by 1, 2, and 3, and j may be represented by 1, 2.

The base station 100 transmits, via each antenna,

Figure pat00054
and
Figure pat00055
The terminal 200 transmits the signal received through each antenna
Figure pat00056
,
Figure pat00057
And
Figure pat00058
Can be expressed by Equation (19).

Figure pat00059

The received signal of Equation (19) can be expressed as Equation (20) in the form of a vector and a matrix variable.

Figure pat00060

In Equation 20, H d may be expressed as a product of a transmission RF chain path gain of the base station 100, a radio channel gain of a forward link, and a reception RF chain path gain of the terminal 200.

Similarly, in the terminal 200,

Figure pat00061
,
Figure pat00062
,
Figure pat00063
The base station 100 transmits the signal received through each antenna
Figure pat00064
,
Figure pat00065
Can be expressed by Equation (21).

Figure pat00066

The received signal of Equation (21) can be expressed as Equation (22).

Figure pat00067

In Equation 22, H u can be expressed as a product of the reception RF chain path gain of the base station 100, the radio channel gain of the reverse link, and the transmission RF chain path gain of the terminal 200.

Thus, all variables are the same as individual antennas, but capitalized variables are used to represent multiple antennas, which means they are vector or matrix variables. A method of calculating a calibration coefficient for beamforming of a forward link on the basis of the expression of such a variable will be described. The procedure is the same as that of FIG. 2 and will be described with reference to FIG.

The base station 100 generates a forward-sounding signal X s and sends a forward sounding signal X s to the MS 200 through each antenna (S202).

The terminal 200 receives the forward sounding signal Y A from the base station 100 through each antenna and the forward sounding signal Y A received from the terminal 200 can be expressed by Equation (23).

Figure pat00068

The received signal of Equation (23) can be expressed as Equation (24), because the sounding signal transmitted from each antenna is a mutually promised signal between the base station 100 and the terminal 200, You will get it.

Figure pat00069

In Equation 24,

Figure pat00070
Denotes a Hermitian matrix of X s .

The terminal 200 can estimate the overall channel gain of the forward link as shown in Equation (25) using Equation (24) (S206).

Figure pat00071

In Equation 25, k 1 is a constant.

After generating the reverse sounding signal X A , the terminal 200 transmits the forward channel full channel gain prediction value < RTI ID = 0.0 >

Figure pat00072
Multiplied by the backward sounding signal X A , and transmitted to the base station 100 (S208).

The base station 100 receives the estimated total channel gain of the forward link from the terminal 200

Figure pat00073
And the reverse sounding signal Y ' S received at the base station 100 may be expressed as Equation (26).

Figure pat00074

The received signal of Equation (26) can be expressed as Equation (27).

Figure pat00075

The base station 100 may calculate the forward channel gain and the reverse link channel gain < RTI ID = 0.0 >

Figure pat00076
(S212).

Figure pat00077

The base station 100 calculates the round-

Figure pat00078
Is stored in the buffer (S214).

The terminal 200 estimates the total channel gain estimate of the forward link

Figure pat00079
After transmitting the multiplied reverse sounding signal to the base station 100, only the backward sounding signal X A is transmitted to the base station 100 through each antenna (S216).

The base station 100 receives a reverse sounding signal from the terminal 200 via each antenna and the reverse sounding signal Y S received from the base station 100 can be expressed by Equation (29).

Figure pat00080

And the received signal of Equation (29) can be expressed as Equation (30).

Figure pat00081

The base station 100 predicts the overall channel gain of the reverse link using Equation (30) (S220). Total channel gain estimate for the reverse link

Figure pat00082
Can be calculated as shown in Equation (31).

Figure pat00083

The base station 100 calculates the total channel gain prediction value of the forward link based on Equation (32)

Figure pat00084
(S222).

Figure pat00085

Equation (32) can be expressed by Equation (33).

Figure pat00086

In Expression 33, the exponent "-1" means an inverse matrix.

The base station 100

Figure pat00087
And the calibration coefficient C is calculated from the relationship of the equation (34) (S224).

Figure pat00088

The base station 100 compensates for the asymmetry between the transmitting and receiving RF chains using the calibration coefficient C.

The method of compensating the asymmetry between the RF chain paths of the multiple transmission / reception antennas may also be the same as the procedure shown in FIG. However, in order to display multiple antennas, capital letters are used in expressing variables.

The terminal 200 transmits the reverse sounding signal X A for each antenna to the base station 100.

The base station 100 receives a backward sounding signal from the terminal 200 (S302). As described above, the base station 100 uses the received reverse direction sounding signal to transmit a reverse link signal including the transmission RF chain path gain of the terminal 200, the radio channel gain of the reverse link, and the reception RF chain path gain of the base station 100, Overall channel gain of

Figure pat00089
(S304).

Next, the base station 100 determines the total channel gain of the reverse link

Figure pat00090
And a calibration coefficient C to calculate a channel compensation weight value (S306). Channel compensation weight value
Figure pat00091
Can be calculated as shown in Equation (35).

Figure pat00092

The base station 100 includes a channel compensation weight value

Figure pat00093
To the data D to be transmitted for each antenna, and transmits the data D to the terminal 200 (S308).

The data Y A received from the terminal 200 can be expressed by Equation (36).

Figure pat00094

At this time, from the definition of the calibration coefficient C of the equation (34), the reception data Y A of the equation (36) can be expressed by the equation (37).

Figure pat00095

Accordingly, the terminal 200 can demodulate the received signal into MRT.

5 is a diagram illustrating a transmitting apparatus according to an embodiment of the present invention.

5, the transmitting apparatus 500 includes a receiving unit 510, a gain calculating unit 520, a calibration calculating unit 530, a beam forming unit 540, and a transmitting unit 550. The transmitting apparatus 500 may be embodied in the base station 100 or the terminal 200 that performs beamforming. For example, when the transmitting apparatus 500 is the base station 100, the receiving apparatus may be the terminal 200, and when the transmitting apparatus 500 is the terminal 200, the receiving apparatus may be the base station 100 have. Hereinafter, it is assumed that the transmitting apparatus 500 is the base station 100.

The receiving unit 510 receives only the backward sounding signal from the receiving apparatus after receiving the signal obtained by multiplying the backward sounding signal by the overall channel gain of the forward link from the receiving apparatus.

The gain calculator 520 calculates the reciprocating channel gain using a signal obtained by multiplying the reverse sounding signal by the total channel gain of the forward link and calculates the overall channel gain of the reverse link using the reverse sounding signal.

Calibration calculation section 530 calculates the calibration coefficient using the reciprocating channel gain and the total channel gain of the reverse link.

The beam forming unit 540 calculates a channel compensation weight value using the total channel gain of the reverse link and the calibration coefficient, and multiplies the channel compensation weight value by the data to be transmitted for each antenna.

The transmitting unit 550 transmits a forward sounding signal through each antenna. The receiving apparatus receiving the forward sounding signal can calculate the overall channel gain of the forward link using the forward sounding signal. The transmission unit 550 transmits data for each antenna multiplied by the channel compensation weight value through each antenna.

At least some of the functions of the calibration and beamforming method according to the embodiments of the present invention described above can be implemented in hardware or in software combined with hardware. For example, a processor implemented as a central processing unit (CPU) or other chipset, microprocessor, etc. performs the functions of the gain calculator 520, the calibration calculator 530, and the beamformer 540 And a transceiver may perform the functions of the receiving unit 510 and the transmitting unit 550.

The embodiments of the present invention are not limited to the above-described apparatuses and / or methods, but may be implemented through a program for realizing functions corresponding to the configuration of the embodiment of the present invention or a recording medium on which the program is recorded, Such an embodiment can be readily implemented by those skilled in the art from the description of the embodiments described above.

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 (12)

A calibration and beam forming method in a transmitting apparatus,
Receiving a first signal multiplied by a total channel gain of a first link from the transmitting device to the receiving device to a first sounding signal from the receiving device,
Calculating a reciprocating channel gain of the second link from the receiver to the transmitter using the first signal;
Receiving the first sounding signal from the receiving device,
Estimating an overall channel gain of the second link using the first sounding signal,
Estimating an overall channel gain of the first link using the reciprocating channel gain and the total channel gain of the second link,
Calculating a calibration factor using the overall channel gain of the first link and the overall channel gain of the second link, and
A step of correcting data to be transmitted for each antenna using the calibration coefficient
≪ / RTI > The method of claim 1,
The step of correcting
Receiving the first sounding signal from the receiving device,
Estimating an overall channel gain of the second link using the first sounding signal,
Calculating a channel compensation weight value using the overall channel gain of the second link and the calibration factor; and
Multiplying the data to be transmitted for each antenna by the channel compensation weight value
≪ / RTI > The method of claim 1,
Wherein receiving the first signal comprises transmitting a second sounding signal to the receiving device,
Wherein the first link channel gain is predicted using the second sounding signal received by the receiving device. The method of claim 1,
The first link is a forward link and the second link is a reverse link when the transmitting apparatus is a base station and the receiving apparatus is a terminal,
Wherein the first link is a reverse link and the second link is a forward link if the transmitting device is a terminal and the receiving device is a base station. The method of claim 1,
Wherein the total channel gain of the first and second links comprises a transmit and receive RF chain path gain and a radio channel gain, respectively. A method for receiving a beamformed signal from a transmitting device in a receiving device,
Receiving a first sounding signal from the transmitting device,
Estimating an overall channel gain of the first link from the transmitter to the receiver using the first sounding signal,
Transmitting a first signal obtained by multiplying a second sounding signal by a total channel gain of the first link to the transmitting device,
Transmitting the second sounding signal, and
Receiving the calibrated data for each antenna using the calibration coefficient from the transmission apparatus that has calculated the calibration coefficient using the first signal and the second sounding signal,
/ RTI > The method of claim 6,
Wherein the calibration coefficient is calculated by using the total channel gain of the second link from the receiving apparatus to the transmitting apparatus calculated using the second sounding signal and the total channel gain of the second link calculated from the first link and the second link, Wherein the channel gain is calculated using the reciprocal channel gain of the receiver. The method of claim 6,
The first link is a forward link and the second link is a reverse link when the transmitting apparatus is a base station and the receiving apparatus is a terminal,
Wherein the first link is a reverse link and the second link is a forward link if the transmitting device is a terminal and the receiving device is a base station. A transmitting apparatus for performing beamforming,
A receiver for receiving the first sounding signal after receiving a first signal multiplied by a total channel gain of a first link from the transmitter to the receiver to a first sounding signal from the receiver,
A gain calculator for calculating a total channel gain of the first link and a total channel gain of the second link from the receiver to the transmitter using the first signal and the first sounding signal,
A calibration calculation unit for calculating a calibration coefficient using the total channel gain of the first link and the total channel gain of the second link,
A beam forming unit for correcting data to be transmitted for each antenna by using the calibration coefficient, and
A transmitter for transmitting the corrected data for each antenna;
. The method of claim 9,
Wherein the gain calculator calculates a reciprocating channel gain of the first link and the second link using the first signal, calculates an overall channel gain of the second link using the first sounding signal, And calculates the calibration coefficient using the total channel gain of the first link and the total channel gain of the second link. 11. The method of claim 10,
Wherein the receiving unit receives the third sounding signal from the receiving device,
Wherein the gain calculator calculates an overall channel gain of the second link using the third sounding signal,
The beamformer calculates a channel compensation weight value using the total channel gain of the second link calculated using the third sounding signal and the calibration coefficient, and then transmits the channel compensation weight value to each antenna A transmitting apparatus for multiplying data. The method of claim 9,
The first link is a forward link and the second link is a reverse link when the transmitting apparatus is a base station and the receiving apparatus is a terminal,
Wherein the first link is a reverse link and the second link is a forward link when the transmitting apparatus is a terminal and the receiving apparatus is a base station.
KR1020140142054A 2014-10-20 2014-10-20 Transmitting apparatus and method for calibration and beamforming thereof, and method for receiving of receiving apparatus KR20160046243A (en)

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