KR101541679B1 - Method and Device for Demodulating Signal in Receiving device of FBMC System - Google Patents

Abstract

Disclosed are a method and a device for demodulating a signal in a reception device of a FBMC system. The method of the present invention comprises the steps of: (a) estimating a channel; (b) generating first conversion information by using the estimated channel in a case where a reception signal transmitted from a multi-antenna is for a real number transmission symbol; (c) generating second conversion information by using the estimated channel in a case where the reception signal is for an imaginary number transmission symbol; (d) converting the reception signal by using the first or second conversion information; and (e) selecting the real or imaginary values from the converted signal in the step (d), wherein the first and second conversion information are to remove components of the imaginary number of the channel from the reception signal. According to the present invention, the reception device that receives the transmission symbol filtered by the FBMC can effectively remove the interrupt between symbols while maintaining a channel gain.

Description

TECHNICAL FIELD The present invention relates to a method and a device for demodulating a signal in an FBMC system receiving apparatus,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for demodulating received signals, and more particularly to a method and an apparatus for demodulating signals in a receiving apparatus of an FBMC system.

OFDM is one of the transmission techniques using multicarrier. It is a fourth generation physical layer transceiver technology following CDMA, which is a third generation communication technology. Currently, it is widely used in wired communication such as VDSL as well as wireless communication such as LTE and Wibro.

However, in the conventional OFDM technology, it is pointed out that a CP (Cyclic Prefix) should be used in order to suppress carrier and symbol interference, and it is pointed out that setting of CP is not suitable for next generation mobile communication where high efficiency is to be obtained.

In order to solve such problems, Filter Bank Multi Carrier (FBMC) technology has been proposed. The FBMC is a technique to perform filtering for each subcarrier with respect to a transmission signal, and it is possible to drastically reduce power leakage outside the effective bandwidth which is problematic in OFDM. Because of this advantage, the FBMC technique can increase the efficiency of the entire frequency band with only CP without using CP or with very small CP.

Although the FBMC has the above advantages, there is a complicated aspect to eliminate interference between adjacent symbols due to the characteristic of the transmission symbol of the FBMC. The real and imaginary components of the FBMC-filtered transmission symbol are alternately repeated. Due to such characteristics, an interference cancellation and demodulation method different from OFDM is required.
Prior art related to the FBMC is US Patent Publication No. US2014 / 0286384.

One aspect of the present invention proposes a signal demodulating method and apparatus in an FBMC system receiving apparatus capable of efficiently removing inter-symbol interference while maintaining a channel gain in a receiving apparatus that receives a transmission signal filtered by an FBMC.

According to an aspect of the present invention, there is provided a method comprising: (a) estimating a channel; (B) generating first conversion information using the estimated channel if a received signal transmitted from multiple antennas is a received signal for a real transmission symbol; (C) generating second transform information using the estimated channel if the received signal is a received signal for an imaginary transmitted symbol; (D) converting the received signal using the first conversion information or the second conversion information; (E) selecting a real or imaginary value from the signal transformed in step (d), wherein the first transform information and the second transform information are generated by removing an imaginary component of a channel from the received signal A method of demodulating a signal in an FBMC system receiving apparatus is provided.

The first conversion information and the second conversion information are in the form of a matrix.

The first transform information and the second transform information are matrices for transforming the received signal so that the received signal is expressed in the form of a square of the absolute value of the channel multiplied by the transmit symbol.

If the received signal is a received signal for a real transmission symbol, the step (d) converts the received signal using a received signal matrix comprising a conjugate of the received signal and the received signal and the first transformed information.

If the received signal is a received signal for an imaginary transmission symbol, the step (d) transforms the received signal using a received signal matrix consisting of a conjugate of the received signal and the received signal and the second transformed information.

When the number of the multiple antennas is two, the matrix G1 for the first conversion information is set according to the following equation.

In the above equation, h ₁ is a channel with the first antenna, and h ₂ is a channel with the second antenna.

If the number of the multiple antennas is two, the matrix G2 for the second conversion information is set as follows.

In the above equation, h ₁ is a channel with the first antenna, and h ₂ is a channel with the second antenna.

According to another aspect of the present invention, there is provided a method comprising: (a) estimating a channel; (B) generating first conversion information using the estimated channel if a received signal transmitted from multiple antennas is a received signal for a real transmission symbol; (C) generating second transform information using the estimated channel if the received signal is a received signal for an imaginary transmitted symbol; (D) converting the received signal using the first conversion information or the second conversion information; And a demodulating step (e) of selecting a real value or an imaginary value from the signal converted in step (d), wherein the first conversion information and the second conversion information are information indicating whether the received signal is an absolute value ≪ / RTI > and the transmission symbol.

According to another aspect of the present invention, there is provided a channel estimation apparatus comprising: a channel estimator for estimating a channel; Generating first conversion information using the estimated channel when a received signal transmitted from multiple antennas is a received signal for a real transmission symbol; A second conversion information generator for generating second conversion information using the estimated channel if the received signal is a received signal for an imaginary transmission symbol; A received signal converting unit for converting the received signal using the first conversion information or the second conversion information; And a demodulator for selecting a real value or an imaginary value from the converted reception signal, wherein the first conversion information and the second conversion information are conversion information for removing an imaginary component of a channel from the reception signal, A signal demodulating device is provided.

According to the present invention, there is an advantage that the interference between symbols can be efficiently removed while maintaining the channel gain in the receiving apparatus that receives the transmission signal filtered by the FBMC.

Brief Description of the Drawings Fig. 1 is a diagram showing a structure of transmission symbols in a general OFDM communication system. Fig.
BACKGROUND OF THE INVENTION Field of the Invention [0001] The present invention relates to an FMBC-filtered transmission symbol, and more particularly,
3 is a block diagram illustrating a structure of a received signal demodulation device in a communication system to which FBMC filtering is applied according to an embodiment of the present invention.
4 is a diagram illustrating an operation of demodulating a signal having a real transmission symbol in a receiving apparatus in an FBMC system receiving apparatus according to an embodiment of the present invention.
FIG. 5 illustrates an operation of demodulating a signal having an imaginary number of a transmission symbol in a receiving apparatus in an FBMC system receiving apparatus according to an embodiment of the present invention. FIG.
6 is a flowchart illustrating an operation of an FBMC system receiving apparatus according to an embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. Like reference numerals are used for like elements in describing each drawing.

1 is a diagram illustrating a structure of a transmission symbol in a general OFDM communication system.

1, the general symbols (S1, S2, S3) are generated for each subcarrier in the OFDM communication system, and may, each sinbol (S1, S2, S3) comprises real and imaginary components, and a symbol r _si + j _si . < / RTI >

Referring to FIG. 1, overlapping intervals S1 + S2 and S2 + S3 may occur. Even if inter-symbol superposition is performed in a general OFDM system, since each symbol includes a real number component and an imaginary number component, the original symbol can be restored if the channel information is known.

2 is a diagram illustrating a structure of an FMBC filtered transmission symbol.

Referring to FIG. 2, unlike the transmission symbol of the OFDM, the FBMC-filtered transmission signal is composed of only the real component of the first symbol S 1, the imaginary component of the second symbol S 2, The symbols of the imaginary component are alternately repeated.

Due to the characteristic of the FBMC transmission symbol, the receiving device restores the original symbol through an operation of selecting only a real component or an imaginary component only.

As shown in FIG. 2, the FBMC filtered symbols may also occur in the overlapping period (S1 + S2, S2 + S3). In the OFDM symbol, each symbol includes real and imaginary components, and both the real component and the imaginary component are included in the overlapping section. Therefore, when the channel is known, restoration of the symbol is not complicated.

However, in a communication system in which FBMC filtering is performed, each symbol consists of only a real component or an imaginary component, and both real components and imaginary components exist in the overlapping period.

When the symbol data of the overlapping section is multiplied by the channel including both the real component and the imaginary component, the imaginary component changes to the real component. If such a change occurs, the real component or the imaginary component is selected in the subsequent operation. Symbols can not but be corrupted.

The present invention provides an apparatus and method for demodulating a received signal in an FBMC system capable of restoring an original symbol in a communication system to which FMBC filtering is applied in which such a problem may occur.

3 is a block diagram illustrating a structure of a received signal demodulation apparatus in a communication system to which FBMC filtering is applied according to an embodiment of the present invention.

3, an apparatus for demodulating an FBMC filtered signal according to an embodiment of the present invention includes a channel estimation unit 300, a first conversion information generation unit 310, a second conversion information generation unit 320, A received signal converting unit 330 and a demodulating unit 340. [

The channel estimating unit 300 receives the FBMMC filtered signal transmitted from the transmitting apparatus and estimates a channel between the transmitting and receiving apparatuses. The channel estimation can be performed in various manners, and the channel estimation is a well-known technique, so a detailed description thereof will be omitted. For example, channel estimation may be performed using a known pilot signal or training symbol.

The channel estimator 300 estimates a channel for each antenna when multiple antennas are used in the transmitter. As described above, the channel includes both a real component and an imaginary component.

The first conversion information generation unit 310 generates conversion information to be applied to a reception signal corresponding to a symbol including a real component in the reception signal. In the present invention, the received signal is transformed and the first transform information generator 310 generates information for transforming the received signal for the real symbol. Here, the type of the conversion information may be a matrix to be applied to the received signal, and the first conversion information (matrix) is multiplied to the received signal.

The second conversion information generation unit 320 generates conversion information to be applied to a reception signal corresponding to a symbol of an imaginary component in the reception signal. The type of the information generated by the second conversion information generation unit may also be a matrix, and the second conversion information (matrix) is multiplied by the received signal.

가 되도록 수신 신호를 변환하는 것이다. 위와 같은 수신 신호 변환을 통해 채널에서 허수 성분은 제거되게 된다. The first transform matrix and the second transform matrix are matrices for removing imaginary components in the estimated channel. Preferably, the first transform matrix and the second transform matrix are matrices for causing the received signal to be expressed as a product of the square of the absolute value of the channel and the transmit sinew. The received signal is made up of the product Hd of the channel H and the transmitted symbol d, while the first and second transform matrices have a received signal

The received signal is converted into the received signal. The imaginary component is removed from the channel through the above reception signal conversion.

A method for generating a first transform matrix and a second transform matrix in a 2 x 1 MISO environment will now be described, but one of ordinary skill in the art will readily understand that the present invention can be applied to various multi-antenna environments.

A process of generating the first transform matrix will be described. The symbols transmitted from the two transmit antennas are defined as d ₁ and d ₂ , and the channels between each antenna and the receive end are defined as h ₁ and h ₂ . Where d ₁ and d ₂ are real numbers.

At this time, the received signal is defined by the following Equation (1).

및

로 변환하기 위한 매트릭스이다. 수신 신호 변환을 위해, 수신 신호 y 및 y의 컨쥬케이트인 y^* 로 이루어진 2 X 1 매트릭스인 Y를 설정한다. 제1 변환 매트릭스(G1)는 다음의 수학식2와 같이 정의되는 매트릭스이다. The first transform matrix is used to transform the final received signal

And

. ≪ / RTI > For the received signal conversion, Y is set as a 2 X 1 matrix of y ^* , which is a conjugate of the received signals y and y. The first transformation matrix G1 is a matrix defined by the following equation (2).

The first transformation matrix G1 defined by Equation (2) can be defined as Equation (3) below.

That is, the first transformation matrix can be generated using the estimated channels h ₁ and h ₂ .

Next, the process of generating the second transform matrix will be described. The symbols transmitted from the two transmit antennas are defined as d ₁ and d ₂ , and the channels between the antennas and the receive end are defined as h ₁ and h ₂ . Where d ₁ and d ₂ are imaginary numbers.

및

로 변환하기 위한 매트릭스이다. G2를 구할 때에 수신 신호 y와 수신 신호 y의 컨쥬게이트인 y*로 이루어진 2 X 1 매트릭스 Y를 이용하며, G2는 다음의 수학식 4와 같이 정의된다. At this time, the second transformation matrix G2 is a matrix for transforming the reception signal

And

. ≪ / RTI > G2 is a 2x1 matrix Y made up of y *, which is a conjugate of the received signal y and the received signal y, and G2 is defined by the following equation (4).

Since the transmission symbols d ₁ and d ₂ are imaginary numbers, G2 is set differently from G1, and G2 calculated from Equation (4) is defined as Equation (5).

When the first conversion information (matrix) and the second conversion information (matrix) are generated, the reception signal conversion section 330 uses the generated first conversion information (matrix) or second conversion information (matrix) Conversion. Converts the received signal using the first conversion information (matrix) when the received signal is a real number symbol, and converts the received signal using the second converted information (matrix) if the received signal is a symbol corresponding to an imaginary value.

As described above, a conjugate of the received signal can be used together when converting the received signal.

When the received signal is converted, the demodulator 340 demodulates the received signal using the converted received signal. As described above, an operation for selecting only the real value or the imaginary value is performed in the demodulation unit 340. Since the received signal is a signal obtained by multiplying the transmitted signal by the channel gain, demodulation using the channel gain is possible.

4 is a diagram illustrating an operation of demodulating a signal having a real transmission symbol in a receiving apparatus in an FBMC system receiving apparatus according to an embodiment of the present invention.

Referring to FIG. 4, the first conversion information (matrix) is multiplied by the received signal. The reception signal is converted by the product of the first conversion information (matrix) and the reception signal. An operation for selecting a real value from the converted received signal is performed. As described above, even if an interference (imaginary component) according to an adjacent symbol occurs by an operation of selecting a real value, it is possible to detect only the original symbol.

The signal output by the real-valued selection operation is a signal in which the channel gain is reflected in the transmission symbol.

5 is a diagram illustrating an operation of demodulating a signal having an imaginary number of a transmission symbol in a receiving apparatus in an FBMC system receiving apparatus according to an embodiment of the present invention.

Referring to FIG. 5, the second conversion information (matrix) is multiplied by the received signal, thereby converting the received signal. An operation for selecting only the imaginary value from the converted reception signal is performed. It is possible to detect only the original symbol even if an interference (real component) according to the adjacent symbol is generated by such an operation of selecting only the imaginary value.

6 is a flowchart illustrating an operation of the FBMC system receiving apparatus according to an embodiment of the present invention.

Referring to FIG. 6, a channel estimation is first performed (step 600). In the system of the present invention in which a plurality of antennas are used, a channel for each antenna is performed. When two transmission antennas are used, two channels are estimated respectively.

When the channel estimation is performed, it is determined whether the currently received symbol is a real symbol or an imaginary symbol (step 602). As described above, in the FBMC system, the real symbol and the imaginary symbol are alternately transmitted, and it is determined whether the currently received symbol is a real symbol or an imaginary symbol.

If the currently received symbol is a real symbol, first conversion information (matrix) is generated (step 604). If the currently received symbol is an imaginary symbol, second conversion information (matrix) is generated (step 606).

The first conversion information (matrix) and the second conversion information (matrix) are conversion information (matrix) for removing the imaginary component of the channel from the received signal, and the first conversion information (matrix) And is generated using the estimated channel.

When the first conversion information (matrix) and the second conversion information (matrix) are generated, the receiving signal conversion is performed by applying one of the first conversion information and the second conversion information based on the shape to the received symbol (step 608 ).

In the case of a real symbol, the generated first conversion information (matrix) is multiplied by the received signal to perform received signal conversion. In the case of the imaginary symbol, the generated second conversion information (matrix) is multiplied by the received signal, . As described above, a conjugate of the received signal may be used with the received signal.

Once the received signal is converted, demodulation is performed to recover the original symbol (step 610). In the demodulation process, an operation of selecting a real value or an imaginary value is performed.

The above-described technical features may be implemented in the form of program instructions that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions recorded on the medium may be those specially designed and constructed for the embodiments or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware device may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

As described above, the present invention has been described with reference to particular embodiments, such as specific elements, and specific embodiments and drawings. However, it should be understood that the present invention is not limited to the above- And various modifications and changes may be made thereto by those skilled in the art to which the present invention pertains. Accordingly, the spirit of the present invention should not be construed as being limited to the embodiments described, and all of the equivalents or equivalents of the claims, as well as the following claims, belong to the scope of the present invention .

Claims (15)

(A) estimating a channel;
(B) generating first conversion information using the estimated channel if a received signal transmitted from multiple antennas is a received signal for a real transmission symbol;
(C) generating second transform information using the estimated channel if the received signal is a received signal for an imaginary transmitted symbol;
(D) converting the received signal using the first conversion information or the second conversion information;
And a demodulating step (e) of selecting a real value or an imaginary value from the signal converted in the step (d)
Wherein the first conversion information and the second conversion information are conversion information for removing an imaginary component of a channel from the received signal.
The method according to claim 1,
Wherein the first conversion information and the second conversion information are in the form of a matrix. 3. The method of claim 2,
Wherein the first conversion information and the second conversion information are matrices for converting the received signal so that a received signal is expressed by multiplying a square of an absolute value of a channel by a transmission symbol, Demodulation method. 3. The method of claim 2,
(D) transforms the received signal using a received signal matrix formed of a conjugate of the received signal and the received signal and the first converted information when the received signal is a received signal for a real transmission symbol Wherein the signal is demodulated in the FBMC system receiving apparatus. 3. The method of claim 2,
When the received signal is a received signal for an imaginary transmission symbol, the step (d) converts the received signal using a received signal metric composed of a conjugate of the received signal and the received signal and the second transformed information And a signal demodulating method in the FBMC system receiving apparatus. 5. The method of claim 4,
Wherein when the number of the multiple antennas is 2, the matrix G1 for the first conversion information is set according to the following equation.

In the above equation, h ₁ is a channel with the first antenna, and h ₂ is a channel with the second antenna. 6. The method of claim 5,
Wherein the matrix G2 for the second transform information is set according to the following equation when the number of the multiple antennas is two.

In the above equation, h ₁ is a channel with the first antenna, and h ₂ is a channel with the second antenna. (A) estimating a channel;
(B) generating first conversion information using the estimated channel if a received signal transmitted from multiple antennas is a received signal for a real transmission symbol;
(C) generating second transform information using the estimated channel if the received signal is a received signal for an imaginary transmitted symbol;
(D) converting the received signal using the first conversion information or the second conversion information;
And a demodulating step (e) of selecting a real value or an imaginary value from the signal converted in the step (d)
Wherein the first conversion information and the second conversion information convert the received signal so that the received signal is a product of a square of an absolute value of the estimated channel and a product of transmission symbols. Way. A channel estimator for estimating a channel;
Generating first conversion information using the estimated channel when a received signal transmitted from multiple antennas is a received signal for a real transmission symbol;
A second conversion information generator for generating second conversion information using the estimated channel if the received signal is a received signal for an imaginary transmission symbol;
A received signal converting unit for converting the received signal using the first conversion information or the second conversion information;
And a demodulator for selecting a real or imaginary value from the converted reception signal,
Wherein the first conversion information and the second conversion information are conversion information for removing an imaginary component of a channel from the received signal. 10. The method of claim 9,
Wherein the first conversion information and the second conversion information are in the form of a matrix. 11. The method of claim 10,
Wherein the first conversion information and the second conversion information are matrices for converting the received signal so that a received signal is expressed by multiplying a square of an absolute value of a channel by a transmission symbol, Demodulation device. 11. The method of claim 10,
When the received signal is a reception signal for a real transmission symbol, the reception signal conversion unit converts the reception signal using a reception signal matrix formed of a conjugate of the reception signal and the reception signal and the first conversion information And the signal demodulating device in the FBMC system receiving apparatus. 11. The method of claim 10,
(D) transforms the received signal using a received signal matrix consisting of a conjugate of the received signal and the received signal and the second transformed information when the received signal is a received signal for an imaginary transmitted symbol Wherein the signal demodulating device comprises: 13. The method of claim 12,
Wherein when the number of the multiple antennas is 2, the matrix G1 for the first transform information is set according to the following equation.

In the above equation, h ₁ is a channel with the first antenna, and h ₂ is a channel with the second antenna.
14. The method of claim 13,
Wherein when the number of the multiple antennas is 2, the matrix for the second transform information is set according to the following equation.

In the above equation, h ₁ is a channel with the first antenna, and h ₂ is a channel with the second antenna.

Images