KR100755125B1 - Equalizer for signal by both single carrier modulation and multi carrier modulation and method thereof - Google Patents

Abstract

An equalizer employing both single-carrier transmission and multi-carrier transmission and an equalization method of the equalizer are provided to equalize all received signals even though a signal generated in a time domain and loaded on single-carrier is received via a channel or a signal generated in a frequency domain and loaded on multi-carrier is received, and output equalized signals. A frequency domain equalizing part(310) equalizes a symbol received by single-carrier transmission or multi-carrier transmission in a frequency domain and outputs frequency domain data(X(K)). An IFFT(Inverse Fast Fourier Transform)(331) converts the frequency domain data into time domain data(x(n)). A multiplexing part(333) outputs one of the frequency domain data and the time domain data as a final equalization result according to a predetermined control signal. A carrier mode determining part(335) detects a pilot signal from the received symbol, outputs the control signal according to a transmission type determined by whether the pilot signal is detected, and makes the multiplexing part output the time domain data in case of the single-carrier transmission.

Description

Equalizer for signal by both single carrier modulation and multi carrier modulation and method

1 is a block diagram of a communication system according to an embodiment of the present invention;

2 is a diagram illustrating a power spectral density of a transmission signal including a pilot signal for mode determination;

3 is a block diagram of an equalizer according to an embodiment of the present invention;

4 is a block diagram of a carrier mode determiner according to an embodiment of the present invention;

5 is a view provided to explain the operation of the pilot detection unit of the present invention, and

6 is a flowchart provided to explain an operation of a carrier mode determiner according to an embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a channel equalizer, which is capable of receiving and equalizing all data by either a single carrier transmission method or a multicarrier transmission method. It is about.

Currently, several standards for terrestrial digital TV transmission have been proposed.

In North America, the Vestigial Side Band (VSB) transmission method is used for digital TV broadcasting. This transmission method is a single carrier method that carries a signal on one carrier. On the other hand, the DVB (Digital Video Broadcasting) transmission method proposed in Europe is a multi-carrier method using an orthogonal frequency division multiplexing (OFDM) method.

In the case of using a single carrier, the receiver uses a nonlinear decision feedback equalizer in the time domain to equalize this signal. However, in the case of an equalizer operating at a symbol frequency in the time domain, in order to equalize a signal having a long time difference by multiple paths, the length of the filter of the adaptive equalizer requires at least several hundred taps before and after the center tap. .

When the signal is generated in the frequency domain, as in the case of multi-carrier, the signal transmitted after being moved to the time domain through IFFT (Inverse Fast Fouier Transform) is transferred to the frequency domain by the FFT (Fast Fouier Transform) process at the receiving end. After the conversion, the zero-forcing equalizer in the frequency domain can be used to implement equalization using a simpler implementation than the nonlinear decision feedback equalizer in the time domain.

However, the zero-polling equalizer implemented in the time domain cannot overcome the disadvantage of requiring a large number of tap filters for equalizing a long delay signal, such as the nonlinear decision feedback equalizer described above.

SUMMARY OF THE INVENTION An object of the present invention is to provide an equalizer and a method for equalizing a single carrier transmission method and a multicarrier transmission method capable of receiving and equalizing all data based on data of a single carrier transmission method and a multicarrier transmission method. Is in.

In order to achieve the above object, the equalizer according to the present invention includes a frequency domain equalizer, an IFFT (Inverse Fast Fouier Transform) unit, a MUX unit and a carrier mode decision unit.

The frequency domain equalizer outputs data X (K) of the frequency domain by equalizing received symbols received in a single carrier transmission scheme or a multicarrier transmission scheme in the frequency domain, and the IFFT unit outputs data X (K) of the frequency domain in a time domain. Convert to data x (n). The MUX unit outputs one of the data X (K) in the frequency domain and the data x (n) in the time domain as a final equalization result according to a control signal output by the carrier mode decision unit.

Here, the carrier mode determiner detects a pilot signal from the received symbol and controls the MUX unit by outputting the control signal according to a transmission method determined based on the detection or not, in the case of a single carrier transmission method. The MUX unit controls to output the data x (n) of the time domain. The carrier mode determiner determines that the received symbol is based on a single carrier transmission method when the pilot signal is detected from the received symbol.

According to another embodiment, the received symbol includes a mode determination symbol for identification of a transmission scheme, including the mode determination symbol in a time domain in the case of a single carrier transmission scheme, and a frequency in the case of a multicarrier transmission scheme. An area includes the symbol for mode determination. In this case, when the carrier mode determination unit fails to detect a pilot signal from the received symbol, which of the mode determination symbols is detected in data X (K) in the frequency domain and data x (n) in the time domain? By determining the transmission method can be determined.

 The equalizer according to another embodiment of the present invention includes a frequency domain equalizer, an Inverse Fast Fouier Transform (IFFT) unit, a MUX unit, and a carrier mode decision unit in the same way as the equalizer.

However, the frequency domain equalization unit receives a symbol including an identifier for identifying which of the single carrier transmission scheme and the multicarrier transmission scheme, and equalizes the received symbol in the frequency domain to obtain data X (K). Outputs Accordingly, the carrier mode determination unit detects the identifier from the received symbol and outputs the control signal according to the transmission method determined based on the detection result to control the MUX unit, but the MUX unit is the single carrier transmission method. It is controlled to output the data x (n) of the time domain.

Here, the identifier is a mode determination symbol included in the received symbol, and the mode determination symbol may be included in the received symbol in the time domain in the case of a single carrier transmission scheme and in the frequency domain in the case of a multicarrier transmission scheme. have. The carrier mode determination unit may determine a transmission scheme by determining which of the mode determination symbols is detected in data X (K) in the frequency domain and data x (n) in the time domain.

In the two equalizer embodiments, when the received symbol is 3780, the mode determination symbol may be composed of four symbols among the 3780 symbols, and the frequency domain equalizer zero-polling in the frequency domain. It is preferable to perform equalization according to the algorithm.

According to a zero-polling algorithm, the frequency domain equalizer performs a first FFT (Fast Fouier Transform) on the received symbol and outputs the first FFT unit and a channel impulse response based on the received symbol. A channel impulse response estimator for estimating and outputting a second FFT unit performing an FFT on the estimated channel impulse response and outputting the equalization by a zero-polling algorithm based on the channel impulse response output from the second FFT unit. And a multiplier outputting an equalization result of the frequency domain by multiplying a coefficient calculated by the coefficient calculator and a symbol output from the first FFT unit.

In addition, the received symbol may be terrestrial digital broadcast data.

The equalization method of the equalizer according to another embodiment of the present invention, the step of outputting the data X (K) of the frequency domain by equalizing the received symbols received in a single carrier transmission method or a multi-carrier transmission method in the frequency domain, Converting the data X (K) in the frequency domain into the data x (n) in the time domain and detecting the pilot signal from the received symbol and determining the data based on the detection method based on the detection method. Outputting X (K) and one of the data x (n) of the time domain as a final equalization result, and outputting the data x (n) of the time domain as a final equalization result in the case of a single carrier transmission method. Can be.

Hereinafter, the present invention will be described in detail with reference to the drawings.

1 is a block diagram of a communication system according to an embodiment of the present invention.

The communication system 100 includes a transmitter 110 and a receiver 130, and uses both a single carrier transmission method such as VSB (Vestigial Side Bands) and a multi-carrier transmission method such as orthogonal frequency division multiplexing (OFDM). Can be. However, the transmitter 110 does not use two transmission methods at the same time. Therefore, the reception device 130 determines whether the received signal is transmitted by one of a single carrier transmission method and a multi-carrier transmission method, and receives a transmission signal transmitted by the transmission device 110 based on the result. To be processed.

The reception device 130 may correspond to a terrestrial digital broadcast receiver, a set-top box, etc. capable of receiving a digital broadcast signal. In this case, the transmitter 110 may correspond to a case of using at least one of the VSB and the OFDM transmission scheme.

The receiver 130 may include a predetermined equalizer to restore a distorted transmission signal while passing through a channel in which additive white Gaussian noise (AWGN) and / or fading are present. In this case, the reception device 130 determines whether the transmission signal transmitted by the transmission device 110 is a multi-carrier transmission method or a single carrier transmission method, and performs equalization of the corresponding method.

To this end, the transmitter 110 inserts a predetermined identifier into the transmission signal for the receiver 130 to determine the mode of the transmission signal. In order to explain the identifier, data transmitted by the transmitter 110 is mapped to 3780 symbols by nQAM (Qadrature Amplitude Modulation). The mapped symbols may be transmitted in the OFDM scheme using 3780 carriers and may be transmitted in the VSB scheme using one carrier.

One method of inserting an identifier is to select and transmit a portion (for example, four data symbols) of a data symbol (for example, 3780 symbols) included in a transmission signal as a mode determination symbol. When there are four mode determination symbols, any value from 0000 to 1111 may be used as the mode determination symbol. However, in the multi-carrier transmission mode and the single-carrier transmission mode, the mode determination identifier is preferably configured differently. For example, in the case of the single carrier transmission method, if the symbol for mode determination is 0000, the mode determination symbol of the multicarrier transmission method is preferably 1111.

In the case of the multi-carrier transmission method, the symbol for mode determination in the frequency domain is spread in the time domain and transmitted to the receiving apparatus 130 by undergoing an Inverse Fast Fouier Transform (IFFT) process. The identifier must be detected by converting it into a signal in the frequency domain. In the case of the single carrier transmission method, since a symbol for mode determination in the time domain is inserted, the receiver 130 detects an identifier from a signal received in the time domain.

Another method of inserting an identifier is to insert a pilot signal into a transmission signal of a single carrier transmission scheme to indicate either a single carrier transmission scheme or a multicarrier transmission scheme.

FIG. 2 is a diagram illustrating Power Spectral Density (PSD) of a transmission signal including a pilot signal for mode determination, and shows that the pilot signals a1 and a2 are located at ± f _C.

When the reception device 130 detects the pilot signals a1 and a2 from the received signal, it may determine that the reception device 130 is by a single carrier transmission method.

However, according to an embodiment, a method of using a mode determination symbol and a method of inserting a pilot signal may be used at the same time. For example, when a pilot signal is inserted to indicate a single carrier transmission method, the receiver 130 determines the first transmission method using the pilot signal. If no pilot signal is detected, the transmission mode is determined by checking the mode determination symbol again. This is because the pilot signal may not be detected for various reasons even when transmitted by the single carrier transmission method.

3 is a block diagram of an equalizer according to an embodiment of the present invention.

The equalizer 300 of the present invention is included in the receiver 130 of FIG. 1 to recover the transmission signal transmitted by the transmitter 110 by receiving and equalizing a signal transmitted from the transmitter 110. The signal transmitted by the transmitter 110 may be distorted by passing through a channel in which AWGN exists as well as inter-symbol interference (ISI: multi-path), and restores and outputs the distorted signal.

The equalizer 300 may equalize all transmission signals by the multi-carrier transmission scheme and the single carrier transmission scheme. To this end, the equalizer 300 determines whether the received signal is based on a multi-carrier transmission method or a single carrier transmission method, and outputs equalization results in a frequency domain and a time domain according to the determination result. Accordingly, the equalizer 300 may equalize all signals by two transmission schemes in one equalizer block without including two equalizers corresponding to the transmission schemes.

To this end, the equalizer 300 uses a zero forcing (Zero) equalizer in the frequency domain. ZF equalizers can be implemented in either the time domain or the frequency domain.

The ZF equalizer implemented in the frequency domain can be equalized through a simpler implementation than the case of using a nonlinear decision feedback equalizer in the time domain in the case of multi-carrier. In addition, the ZF equalizer implemented in the frequency domain is a form in which the relationship between a signal and a channel is converted from a linear convolutional relation to a circular convolutional relation, thereby transversal in the time domain. Compared to the filter, the implementation is simpler, has the same hardware, and can eliminate the ghost signal inserted into the received signal through a long path.

Equalizer 300 according to an embodiment of Figure 3 is shown based on the ZF equalizer in the frequency domain.

Frequency domain ZF equalization corresponding to a single carrier transmission method is a method of dividing a received symbol in a frequency domain by an estimate of a channel impulse response, and inversely converting the result of the division into a time domain. The ZF equalization corresponding to the single carrier transmission scheme may be expressed by Equation 1 below.

Where x (n) is the symbol transmitted by the transmitter 110, U (K) is the data of the frequency domain of the symbol received by the receiver 130, and H (K) is the channel impulse response of the frequency domain. It is an estimate. Z ^-1 represents an inverse transform algorithm from the frequency domain to the time domain.

In the frequency domain ZF equalization corresponding to the multicarrier transmission scheme, a process of inverse transforming into the time domain in Equation 1 is omitted, and may be represented by Equation 2 below.

ZF equalization according to Equations 1 and 2 differs only in whether there is a process of inversely converting X (K) obtained in the frequency domain into a symbol in the time domain.

Referring to FIG. 3, the equalizer 300 includes a frequency domain equalizer 310, an IFFT (Inverse Fast Fouier Transform) unit 331, a MUX unit 333, and a carrier mode determiner 335. 3 shows an example of determining a carrier transmission method using both a pilot signal and a mode determination symbol. However, as described above, the carrier transmission method may be determined using only one of a pilot and a mode determination symbol.

The frequency domain equalizer 310 may include a first fast transform transform unit 311, a channel impulse response estimate (CIR) 313, a second FFT unit 315, and a coefficient calculator 317. ) And a multiplier 319.

The first FFT unit 311 converts the input symbol u (n) in the time domain into the symbol U (K) in the frequency domain by using the FFT algorithm and outputs the converted symbol to the multiplier 319. Here, K is a frequency index corresponding to 1 to N when time domain data is converted into frequency domain data using an N-point FFT.

The channel impulse response estimator 313 estimates the impulse response h (n) of the communication channel based on the input symbol u (n) and outputs the impulse response h (n) to the second FFT unit 315. Converts h (n) into a channel impulse response H (K) in the frequency domain and outputs it to the coefficient calculator 317.

The coefficient calculator 317 obtains U (K) ^-1, which is the inverse of the H (K) received from the second FFT unit 315, and outputs the result to the multiplier 319 to output U (K) that is the output of the first FFT unit 311. Multiply by

The multiplication result of the multiplier 319 becomes equalization output X (K) in the frequency domain, and is output to the MUX unit 333 and the carrier mode decision unit 335. In the case of a symbol by a multicarrier transmission scheme, the equalization output X (K) in the frequency domain is a final equalization output to be obtained. However, in case of a transmission symbol using a single carrier transmission method, it is necessary to inversely convert it back to the time domain.

The IFFT unit 331 obtains the data x (n) of the time domain by performing an IFFT algorithm on the output X (K) of the multiplier, and outputs the data to the MUX unit 333 and the carrier mode determiner 335. The result of the IFFT unit 331 becomes a valid value only in the case of a symbol transmitted by a single carrier transmission method.

The MUX unit 333 receives X (K) from the multiplier 319, receives x (n) from the IFFT unit 331, and then, according to the control of the carrier mode decision unit 335, In the case of X (K) and in the case of a single carrier transmission method, x (n) is output. The output of the MUX unit 333 should be determined according to whether the symbol received by the receiver 130 is a single carrier transmission method or a multicarrier transmission method, and the determination is made to the carrier mode decision unit 335. Is made by By selectively outputting the equalization result by the MUX unit 333, the receiver 130 and the equalizer 300 receive and equalize all transmission signals of either a single carrier transmission scheme or a multicarrier transmission scheme and transmit the original signal. The symbol can be restored.

The carrier mode decision unit 335 receives the input symbol u (n) in the time domain, the output X (K) of the multiplier 319, and the output x (n) of the IFFT unit 331 to receive the input symbol u (n). Determine the transmission method.

The operation of the carrier mode determination unit 335 will be described with reference to FIGS. 4 to 6 below.

4 is a block diagram of a carrier mode determiner according to an embodiment of the present invention.

The carrier mode determination unit 400 of FIG. 4 is an example of using both a pilot signal using method and a symbol using method for mode determination. The pilot signal is included in a symbol according to a single carrier transmission method. The carrier mode decision unit 400 of FIG. 4 is an example of the carrier mode decision unit 335 of FIG. 3.

The carrier mode determiner 400 includes a pilot detector 410 and a MUX controller 430.

The pilot detector 410 detects a pilot signal from the input symbol u (n) during the first reference time, and outputs the corresponding information to the MUX controller 430 when the pilot signal is detected. The operation of the pilot detector 410 will be described again below.

When the MUX controller 430 receives the information that the pilot signal is detected from the pilot detector 410 within the first reference time, the MUX controller 430 determines that the input symbol u (n) is a symbol by a single carrier transmission method and returns to the MUX unit 333. Control to output the equalization result x (n) of the IFFT unit 331.

If the MUX controller 430 does not receive the information indicating that the pilot signal is detected from the pilot detector 410 within the first reference time, the MUX controller 430 selects a symbol for mode determination that will be included in either X (K) or x (n). The carrier transmission method is used to determine. In this case, the MUX control unit 430 determines whether the multicarrier mode determination symbol (eg, 1111) is included in X (K) or more than the reference number of times during the second reference time, or in x (n) for the single carrier mode determination. It is determined whether the symbol (for example, 0000) is included more than the reference number of times. Through this process, the MUX control unit 430 may detect a symbol for determining the number of times more than the reference number of times only in one of X (K) and x (n), it may determine the carrier transmission mode.

These determinations may be made at the same time, or may be made in a sequential order. In the case of sequential detection, the MUX controller 430 determines whether the mode determination symbol 0000 is detected more than the reference number of times for the second reference time in order to detect the single carrier mode, and if not detected, In order to detect the carrier mode, it may be determined during the second reference time whether the mode determination symbol 1111 is detected more than the reference number of times by X (K). Of course, the opposite is also possible.

Through this process, the MUX control unit 430 controls the MUX unit 333 to output the equalization result X (K) or x (n) when the mode determination symbol is detected.

According to an embodiment, the carrier mode determiner 400 first performs a process of determining a carrier transmission method using a mode determination symbol included in X (K) and x (n), and determines a mode through this. If no, the pilot signal can be used to determine the mode. In this case, the carrier mode determination unit 400 may change its configuration in a corresponding manner.

According to another embodiment, as described above, the carrier mode determination unit 400 may use only one of a pilot signal using method and a mode determining method using a symbol. In this case, the carrier mode determining unit 400 may use a pilot detector. It may include only one of the 410 and the MUX control unit 430.

5 is a view provided to explain the operation of the pilot detection unit of the present invention.

The method for detecting the pilot signal may use only one of the pilot signals a1 and a2 of FIG. 2, or both. In either method, the carrier mode is determined by integrating the DC signal obtained by bringing the pilot signal to frequency 0 (f = 0), and then determining the absolute value of the complex output for power measurement and determining whether or not it is above a predetermined reference value. Determine. If a pilot signal is present (ie, in the single carrier transmission mode), then the magnitude of the integrated signal will be greater than or equal to the reference value. 5 relates to a method of determining a carrier mode using a pilot signal a1 located at -fc.

Referring to FIG. 5, the pilot detector 500 includes a multiplier 501, an integrator 503, an absolute value calculator 505, and a pilot determiner 507, of the pilot detector 410 of FIG. 4. One example.

The multiplier 501 multiplies the input symbol u (n) by e ^{j2πf _c t} , The pilot signal a1 located at -fc is at frequency 0 (f = 0), the integrator 503 integrates the DC component of the output of the multiplier 501, and the absolute value calculator 505 measures power. For this purpose, the absolute value of the complex output of the integrator 503 is obtained and output to the pilot determination unit 507. The pilot determining unit 507 determines whether the output of the absolute value calculating unit 505 is equal to or greater than the reference value during the first reference time, and determines that the pilot signal is detected when the reference value is greater than or equal to the reference value, that is, in the single carrier mode.

According to an embodiment, in order to determine the carrier mode using the pilot signal a2 located at + fc, e ^{-j2πf _c t} may be multiplied by u (n) instead of e ^{j2πf _c t} .

, 즉 cos2πf_ct를 u(n)에 곱하면 된다. 다중경로 간섭이라든가 시변하는 모바일 채널에서는 어느 한쪽의 파일롯 신호가 채널에 의해 감소되어 검출이 어려울 경우도 있으므로 양쪽의 파일롯 신호를 이용한다면 모드 검출 효율이 높아질 수 있다.According to another embodiment, if the carrier mode is determined using both pilot signals a1 and a2 located at + fc and -fc, instead of e ^{j2πf _c t} .

In other words, multiply cos2πf _c t by u (n). In a multi-channel interference or time-varying mobile channel, either pilot signal may be reduced by the channel and thus difficult to detect. Therefore, if both pilot signals are used, mode detection efficiency may be increased.

In addition, the method of using both pilot signals a1 and a2 requires less hardware since the multiplier can be simpler than the multiplier 501 of FIG.

6 is a flowchart provided to explain an operation of a carrier mode determiner according to an embodiment of the present invention. Hereinafter, the operation of the carrier mode determination unit 400 will be described with reference to FIGS. 1 to 6.

First, the pilot detector 410 performs an operation for detecting a pilot signal according to the description of FIG. 5 (S601), and determines whether a pilot signal is detected during a first reference time. The pilot detector 410 outputs information on whether the pilot signal is detected to the MUX controller 430 (S603).

When the MUX control unit 430 receives the information indicating that the pilot signal is detected from the pilot detection unit 410, the MUX control unit 430 determines that the single carrier transmission method is performed (S605), and causes the MUX unit 333 to output the output x (of the IFFT unit 331). n) is controlled to output (S607).

If the MUX control unit 430 does not receive the information that the pilot signal is detected from the pilot detector 410 during the first reference time, after the determination of step S603, from the X (K) and x (n) during the second reference time. The mode determination symbol is extracted (S609 and S611).

The MUX control unit 430 determines which mode determination symbol is detected more than the reference number of times during the second reference time (S613), and determines the carrier mode. That is, if the mode determination symbol detected more than the reference number of times is 1111, it is determined as a multi-carrier mode, and if it is 0000, it is determined as a single carrier mode (S615). According to the result, the MUX unit 333 controls to output one of the output x (n) of the IFFT unit 331 and the output X (K) of the multiplier 319 (S617).

By the above method, the operation of the carrier mode determination unit 400 according to the present invention is performed.

The invention can be implemented in methods, devices and systems. In addition, when the present invention is implemented in computer software, the components of the present invention may be replaced with code segments necessary for performing necessary operations. The program or code segment may be stored in a medium that can be processed by a microprocessor and transmitted as computer data coupled with carrier waves via a transmission medium or communication network.

The media that can be processed by the microprocessor include electronic circuits, semiconductor memory devices, ROMs, flash memory, electrically erasable programmable read-only memory (EEPROM), floppy disks, optical disks, and hard disks. (Hard) Includes the ability to transmit and store information such as disks, fiber optics, wireless networks, and the like. Computer data also includes data that can be transmitted over electrical network channels, optical fibers, electromagnetic fields, wireless networks, and the like.

In addition, although the preferred embodiment of the present invention has been shown and described above, the present invention is not limited to the above-described specific embodiment, the technical field to which the invention belongs without departing from the spirit of the invention claimed in the claims. Of course, various modifications can be made by those skilled in the art, and these modifications should not be individually understood from the technical spirit or the prospect of the present invention.

As described in detail above, the equalizer according to the present invention receives a signal generated in the time domain like a VSB (Vestigial Side Band) transmission method on a single carrier and is transmitted through a channel, or is generated in a frequency domain like an OFDM () transmission method. Even if the received signal is received on a multi-carrier, it can be equalized and output.

In particular, in the case of a system for transmitting a signal generated in the time domain and a signal generated in the frequency domain by mode switching, the equalizer of the present invention equalizes the same structure and performance by equalizing the signal in the frequency domain regardless of the transmission method. Enable equalization.

The present invention proposes a simple and effective carrier mode determination algorithm, thereby making it possible to simply implement an equalizer that can be used for both a single carrier transmission scheme and a multicarrier transmission scheme.

Claims (15)

A frequency domain equalizer for outputting data X (K) in a frequency domain by equalizing received symbols received in a single carrier transmission scheme or a multicarrier transmission scheme in a frequency domain; An Inverse Fast Fouier Transform (IFFT) unit for converting the data X (K) in the frequency domain into the data x (n) in the time domain; A MUX unit outputting one of data X (K) in the frequency domain and data x (n) in the time domain as a final equalization result according to a predetermined control signal; And A pilot signal is detected from the received symbol, and the MUX unit is controlled by outputting the control signal according to a transmission method determined based on the detection. In the case of a single carrier transmission method, the MUX unit controls data of the time domain. and a carrier mode determiner for controlling to output x (n). The method of claim 1, And the carrier mode determiner determines that the received symbol is based on a single carrier transmission method when the pilot signal is detected from the received symbol. The method of claim 2, The received symbol includes a mode determination symbol for identification of a transmission scheme, includes a mode determination symbol in a time domain in the case of a single carrier transmission, and a mode determination symbol in the frequency domain in the case of a multicarrier transmission. Include, The carrier mode determiner determines whether the mode determining symbol is detected in data X (K) in the frequency domain or data x (n) in the time domain when the pilot signal is not detected from the received symbol. The equalizer characterized in that for determining the transmission method. A frequency domain for receiving a symbol including an identifier for identifying which of the single carrier transmission scheme and the multicarrier transmission scheme, and outputting data X (K) of the frequency domain in which the received symbol is equalized in the frequency domain; stoker; An IFFT unit converting the data X (K) in the frequency domain into data x (n) in the time domain; A MUX unit outputting one of data X (K) in the frequency domain and data x (n) in the time domain as a final equalization result according to a predetermined control signal; And The MUX unit is controlled by detecting the identifier from the received symbol and outputting the control signal according to a transmission method determined based on the detection result. In the case of a single carrier transmission method, the MUX unit includes data x of the time domain. n) a carrier mode determiner for controlling to output the equalizer. The method according to claim 1 or 4, And the received symbol is terrestrial digital broadcast data. The method according to claim 1 or 4, And the frequency domain equalizer performs equalization according to a zero forcing algorithm of the frequency domain. The method of claim 6, The frequency domain equalizer, A first FFT unit configured to output a FFO (Fast Fouier Transform) on the received symbol; A channel impulse response estimator for estimating and outputting a channel impulse response based on the received symbol; A second FFT unit performing an FFT on the estimated channel impulse response and outputting the FFT; A coefficient calculator which obtains the inverse of the channel impulse response output from the second FFT unit and outputs the inverse as a coefficient for equalization; And And a multiplier outputting an equalization result of the frequency domain by multiplying a symbol output from the coefficient calculator by the symbol output from the first FFT unit. The method of claim 4, wherein The identifier is a symbol for mode determination included in the received symbol. The mode determining symbol is included in the received symbol in the time domain in the case of a single carrier transmission method, respectively in the frequency domain in the case of a multi-carrier transmission method. The method of claim 3 or 8, If the received symbol is 3780, the mode determination symbol, characterized in that consisting of four symbols of the 3780 symbols. The method of claim 8, And the carrier mode determiner determines a transmission method by determining which of the mode determination symbols is detected in data X (K) in the frequency domain and data x (n) in the time domain. . Outputting data X (K) in the frequency domain by equalizing the received symbols received in the single carrier transmission method or the multi-carrier transmission method in the frequency domain; Converting the data X (K) in the frequency domain into data x (n) in the time domain; And While detecting a pilot signal from the received symbol and outputting one of the data X (K) in the frequency domain and the data x (n) in the time domain as a final equalization result according to a transmission scheme determined based on the detection. And outputting the data x (n) in the time domain as a final equalization result in the case of a carrier transmission method. The method of claim 11, The outputting of the data X (K) in the frequency domain may include performing equalization according to a zero-polling algorithm in the frequency domain. The method of claim 11, The outputting of the final equalization result may include determining that the received symbol is based on a single carrier transmission method when the pilot signal is detected from the received symbol. The method of claim 13, The received symbol includes a mode determination symbol for identification of a transmission scheme, includes a mode determination symbol in a time domain in the case of a single carrier transmission, and a mode determination symbol in the frequency domain in the case of a multicarrier transmission. Include, In the outputting of the final equalization result, when the pilot signal is not detected from the received symbol, the symbol for mode determination may be selected from any one of data X (K) in the frequency domain and data x (n) in the time domain. An equalization method of an equalizer, characterized in that the transmission method is determined by determining whether it is detected. The method of claim 14, And if the received symbol is 3780, the symbol for mode determination comprises four symbols among the 3780 symbols.

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