KR101065590B1 - Data demodulation method for decreasing effect of impulsive noise based on multi-carrier and apparatus thereof - Google Patents

Abstract

Disclosed are a multi-carrier based data demodulation method and apparatus for reducing the influence of impulsive noise. The data demodulation method according to an embodiment of the present invention is a multi-carrier based data demodulation method for demodulating data from a received signal corresponding to a data symbol having the same absolute value at a constant period of a time domain index in the time domain. Dividing a signal into a plurality of groups comprising the time domain index of the predetermined period; Calculating signal quality values for each of the plurality of groups; Determining whether each of the groups is normal based on the calculated signal quality values for each of the groups; And demodulating the data transmitted through the data symbol at the transmitter by converting at least one normal group determined to be normal into a frequency domain.

Impulsive Noise, Multiple Carriers, Power Lines, Data Demodulation

Description

TECHNICAL DEMODULATION METHOD FOR DECREASING EFFECT OF IMPULSIVE NOISE BASED ON MULTI-CARRIER AND APPARATUS THEREOF

TECHNICAL FIELD The present invention relates to data demodulation, and more particularly, to a constant of a time domain index transmitted from a transmitter in order to minimize the effect of impulsive noise in an orthogonal frequency division multiplex (OFDM) communication system. By receiving data symbols configured to have the same absolute value in periods and demodulating the data through a received signal in a time domain that is not affected by impulsive noise, it is possible to avoid problems that may be caused by impulsive noise in demodulating data. The present invention relates to a multi-carrier based data demodulation method and apparatus for reducing the influence of impulsive noise.

Efforts have been made to construct a power line network using power line communication technology to existing power lines developed for power energy transmission, and are currently being commercialized.

The power line network is divided into high voltage and low voltage, indoor and outdoor, low speed and high speed, and research on each power line network has been conducted all over the world, and recently, research on access network using power line communication has been actively conducted in the US and Europe. It is becoming.

The access network uses optical communication as a backbone network and connects to the customer by using a high voltage underground or overhead distribution line and a low voltage power line. When an access network using powerline communication is established, Internet service, automatic meter reading (AMR) service, and load management service are possible.

Since power lines are not developed for the purpose of communication lines, power line communication channels are frequency selective channels and there can be a variety of colored noises.

In the power line communication system, multi-carrier transmission methods such as Discrete Multi-Tone (DMT) and Orthogonal Frequency Division Multiplexing (OFDM) technologies are used for efficient transmission of high-speed power line communication. The pilot and the data to be transmitted are allocated to each of a plurality of subcarriers, converted into a time domain, and transmitted to a receiver through a power line.

In the power line communication system, as in the example shown in FIG. 1, there is an impulsive noise that is five times larger than the average noise level, which is caused by peripheral power devices, circuits, and electrical causes. Can be generated.

Of course, impulsive noise may be present in general wireless communication systems as well as in power line communication systems.

Packets transmitted from the transmitter to the receiver through the transmission path may be damaged by the effects of these impulsive noises, so that some of the packets may be damaged, requiring complicated methods for restoration to recover the damaged packets from the receiver. The packet may also be re-requested and received.

As such, the system has a problem of degrading system performance due to problems that may be caused by impulsive noise.

Therefore, there is a need for a method capable of minimizing the effects of impulsive noise.

An object of the present invention, which is designed to solve the above problems, is to receive a data symbol having the same absolute value at a constant period of a time domain index in a time domain transmitted from a transmitter, and By demodulating the data transmitted by the data symbols by changing the normal region unaffected by impulsive noise to the frequency domain, the effects of impulsive noise can be eliminated to prevent problems caused by impulsive noise. A multi-carrier based data demodulation method and apparatus are provided.

Furthermore, another object according to an embodiment of the present invention is to restore an abnormal region of a data symbol affected by impulsive noise during data demodulation using a normal region, and then demodulate data transmitted by the data symbol. The present invention provides a multi-carrier based data demodulation method and apparatus capable of improving system performance by minimizing the effects of noise.

In order to achieve the above object, a data demodulation method according to an aspect of the present invention is a multi-carrier based data demodulation for demodulating data from a received signal corresponding to a data symbol having the same absolute value at a constant period of a time domain index in the time domain. 10. A method, comprising: separating the received signal into a plurality of groups comprising the time domain index of the predetermined period; Calculating signal quality values for each of the plurality of groups; Determining whether each of the groups is normal based on the calculated signal quality values for each of the groups; And demodulating the data transmitted through the data symbol at the transmitter by converting at least one normal group determined to be normal into a frequency domain.

Preferably, the determining may determine a group having a signal quality value equal to or less than a preset multiple compared to the minimum signal quality value as compared with the minimum signal quality value among the signal quality values for the plurality of groups as a normal group. have.

Further, the demodulating may be performed by restoring the abnormal group determined to be abnormal by the determining using the normal group, converting the received signal from which the abnormal group is restored to a frequency domain, and transmitting the data through the data symbol. Demodulated data can be demodulated.

Preferably, the determining may include comparing each of the signal quality values for the plurality of groups to determine whether a ratio of two signal quality values to be compared is greater than or equal to a preset reference threshold value, and the ratio of the two signal quality values to the reference threshold value. In the above case, a group having a smaller value among the two signal quality values may be determined as a normal group.

A data demodulation device according to an aspect of the present invention is a multi-carrier based data demodulation device for demodulating data from a received signal corresponding to a data symbol having a same absolute value at a predetermined period of a time domain index in a time domain. A separating unit for dividing a into a plurality of groups including the time domain indexes of the predetermined period; A calculator for calculating signal quality values for each of the plurality of groups; A determination unit determining whether each of the groups is normal based on the calculated signal quality values for each of the groups; And a demodulator for converting at least one normal group determined to be normal into a frequency domain and demodulating data transmitted through the data symbol by a transmitter.

In this case, the determining unit determines the group having a signal quality value equal to or less than a predetermined multiple compared to the minimum signal quality value as a normal group by comparing with the minimum signal quality value among the signal quality values for the plurality of groups, Comparing each of the signal quality values for the group, it is determined whether the ratio of the two signal quality values to be compared is equal to or greater than a preset reference threshold, and when the ratio of the two signal quality values is equal to or greater than the reference threshold, The group can be determined as a normal group.

Other objects and features of the present invention in addition to the above objects will be apparent from the description of the embodiments with reference to the accompanying drawings.

Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In describing the present invention, when it is determined that the detailed description of the related well-known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

Hereinafter, a multi-carrier based data demodulation method and apparatus for reducing the influence of impulsive noise according to an embodiment of the present invention will be described in detail with reference to FIGS. 2 to 8.

Impulsive noise may be generated by surrounding power devices and circuits or by electrical causes in power line communication, or may be generated by the surrounding environment in wireless communication using an antenna. When transmitting a packet from the transmitter to the receiver, the impulse noise can cause the symbols that make up the packet to be broken, which can cause problems in the receiver's channel estimation and data demodulation, which can degrade system performance. have.

The present invention receives data symbols having the same absolute value at a constant period of a time domain index in a time domain transmitted from a transmitter, and uses received signals in a normal region that are not affected by impulsive noise when demodulating data transmitted from the data symbols. By demodulating the data, the present invention aims to improve the performance of a multi-carrier based communication system by eliminating the influence of impulsive noise and thereby minimizing the problems caused by the impulsive noise.

2 shows a communication system for explaining a data demodulation device according to an embodiment of the present invention, and shows a power line communication system as an example.

Referring to FIG. 2, the system includes a transmitter 210, a power line 220, and a receiver 230.

The transmitter 210 transmits data to a plurality of subcarriers constituting a data symbol so that data demodulation can be performed by eliminating or minimizing the influence of impulsive noise in the data demodulation device of the present invention included in the receiver 230. When allocating, the data symbols converted to the time domain are allocated to have the same absolute value at a predetermined period of the time domain index, and then converted to the time domain and transmitted to the receiver 230 through the power line 220.

Such a method of allocating data to a plurality of subcarriers constituting a data symbol in the transmitter 210 is described in application No. 10-2009-0037431 filed by the same inventor.

Briefly describing the contents described in the application number 10-2009-0037431, by separating a plurality of subcarriers into a plurality of groups, by assigning the data or zero to be transmitted to each of the separated plurality of groups, The data symbols have the same absolute value at a constant period of time domain index in the time domain. When a transmitter transmits such a data symbol, the data symbol is received by the receiver due to impulsive noise, even though the information of one region of the data symbol is broken. It describes that data demodulation is possible using the same information in different areas of the symbol.

The power line 220 serves as a transmission path for transmitting the packet converted into the time domain by the transmitter 210 to the receiver 230.

At this time, the power line 220 transmits the impulse noise generated by the peripheral power device constituting the power system, the device constituting the power line communication system, and the circuit and the electrical cause, etc. The present invention is directed to such impulsive noise. This is to improve system performance by minimizing the problems caused by the system.

Of course, in the case of a wireless communication system, the standby serves as a transmission path.

Here, the packet transmitted through the transmission path includes a preamble (or frame separator) 310, a long symbol 320, and a data symbol 330, as shown in FIG. 3.

The preamble 310 is a delimiter for classifying frames and includes information on synchronization and automatic gain adjustment (AGC).

The long symbol 320 is a symbol required for estimating a channel, and a preset pilot may be allocated. The long symbol 320 may be two or may be included in the preamble 310.

The data symbol 330 is a symbol to which actual data is assigned, and the method of allocating data to the data symbol is as described above.

The receiver 230 receives a packet transmitted from the transmitter 210 through the power line 220 and performs functions such as synchronization and automatic gain adjustment, channel estimation, data demodulation, and channel decoding using the received packet.

Here, as shown in FIG. 4, the receiver 230 includes a synchronization and automatic gain adjustment unit 410, a channel estimator 420, a data demodulator 430, and a channel decoder 440. The automatic gain adjustment unit 410 performs synchronization and automatic gain adjustment using information on synchronization and automatic gain adjustment (AGC) included in the preamble constituting the packet, and the channel estimator 420 uses the long symbol. The data demodulator 430 demodulates the data transmitted through the data symbol by using the channel information estimated by the channel estimator 420, and the channel decoder 440 demodulates the channel. Channel decoding is performed using the data.

Here, the synchronization and automatic gain adjuster 410, the channel estimator 420 and the channel decoder 440 may distract the technical gist of the data demodulator 430 corresponding to the data demodulator according to the present invention. Detailed description will be omitted.

Hereinafter, in the present invention, it is assumed that the channel is estimated by various methods in which the channel estimator 420 estimates the channel.

FIG. 5 illustrates a configuration of a data demodulation device according to an embodiment of the present invention, and corresponds to the data demodulator 430 shown in FIG. 4.

Referring to FIG. 5, the data demodulation device includes a separator 510, a calculator 520, a determiner 530, and a demodulator 540.

The separating unit 510 divides a received signal corresponding to a data symbol received by the data demodulation device into a plurality of groups including a time domain index of a predetermined period.

Here, the constant period used to separate the received signal corresponding to one data symbol into a plurality of groups in the separator 510 refers to a period in which the same absolute value is repeated when the transmitter converts the data symbol into the time domain.

That is, the separating unit 510 divides the received signal corresponding to the data symbol into a plurality of groups by setting a group so that the received signal corresponding to the data symbol has a number of time domain indexes corresponding to a predetermined period. For example, assuming that a received signal corresponding to one data symbol includes N time domain indexes and a predetermined period is N / 4, the separating unit 510 may determine that the received signal has a time domain index of 0 to (N / 4−). 1) the first group which is N / 4 ~ (2N / 4-1), the second group which is 2N / 4 ~ (3N / 4-1) and the third group which is 3N / 4 ~ (N-1) Separate into 4 groups.

In this case, the received signal corresponding to the data symbol received by the data demodulation device may be represented by Equation 1 below.

Here, n denotes a time domain index, m denotes a data symbol index, r denotes a received signal corresponding to a data symbol, x denotes a data symbol converted to a time domain, and h denotes an estimated The channel means z and impulse noise and white noise present in the power line.

Therefore, the separating unit 510 divides the received signal r _n ^(m) into a time domain corresponding to a predetermined period, thereby separating the received signal into a plurality of groups.

The calculator 520 calculates signal quality values for each of the plurality of groups separated by the separator 510.

Here, the signal quality value of each group calculated by the calculation unit 520 is a value for determining whether impulsive noise is included in the corresponding group, and may be calculated by various methods. For example, Equation 2 below. It can also be calculated as>.

, i=0, 1,..., K-1

, i = 0, 1, ..., K-1

Here, Q denotes a signal quality value, N denotes the number of time domain indexes, K denotes the number of times that the same information is repeated in the time domain, and i denotes a group index separated by a separator.

That is, as shown by Equation 2, the calculation unit 520 takes the absolute value of the received signal for each time domain index corresponding to the corresponding group, squares the absolute value, and adds the sum to the corresponding group. The signal quality value can be calculated.

The determination unit 530 determines whether each of the groups is a normal normal group or an abnormal abnormal group by using signal quality values of each group calculated by the calculation unit 520.

Here, the normal group refers to a group that does not include an error because it is not affected by impulsive noise, and the abnormal group refers to a group that includes an error under the influence of an impulsive noise. That is, the normal group means a group in which impulsive noise has not occurred, and the abnormal group means a group in which impulsive noise occurs.

The determination unit 530 may determine a normal group and an abnormal group by applying various methods in consideration of impulsive noise, for example.

1) The determination unit 530 may determine a normal group and an abnormal group by using a minimum signal quality value among the signal quality values of each group.

That is, the determination unit 530 detects the minimum signal quality value among the calculated plurality of signal quality values and compares the minimum signal quality value with a preset multiple less than or equal to the minimum signal quality value, for example, 1.5 times or 1.6 times. , A group having a signal quality value of 2 times or less is determined as a normal group, and a group not determined as an abnormal group.

2) The determination unit 530 may determine a normal group and an abnormal group by using a ratio of each of the calculated plurality of signal quality values.

That is, the determination unit 530 calculates a ratio of two signal quality values for two groups of the plurality of groups, determines whether the ratio of the calculated two signal quality values is equal to or greater than a preset reference threshold Th, and determines a reference threshold ( In the case of Th) or more, a small group of two signal quality values is determined as a normal group, and a large group is determined as an abnormal group.

For example, the received signal is divided into four groups G1, G2, G3 and G4, and the signal quality values for each group are Q1, Q2, Q3 and Q4, and Q1 / Q2, Q2 / Q1, Q1 / Q3 and Q3 /. If Q1 is all smaller than the reference threshold and Q4 / Q1 is equal to or greater than the reference threshold, the determination unit determines G1, G2, G3 as a normal group, and determines G4 as an abnormal group.

Of course, in the method of comparing two signal quality values, the remaining signal quality values were compared based on Q1, but it is not limited thereto, and it is also possible to compare the signal quality values using various methods. Self-explanatory

The demodulator 540 demodulates the data transmitted through the corresponding data symbol by the transmitter by converting the normal group determined by the determination unit 530 into the frequency domain.

In this case, the demodulator 540 may restore the abnormal group determined by the determination unit 530 using the normal group. When there are a plurality of normal groups, the demodulator 540 may copy the normal group having the minimum signal quality value to the abnormal group. The abnormal group can be restored to the normal group.

Of course, when the abnormal group is restored by the normal group, the demodulator 540 converts a received signal corresponding to the data symbol from which the abnormal group is restored, that is, a received signal for N time domain indexes, into a frequency domain and then converts the received signal into a frequency domain. Demodulate data transmitted via data symbols.

In addition, the demodulator 540 may demodulate the data transmitted through the corresponding data symbol by using the channel information estimated by the receiver.

That is, the demodulator 540 obtains the frequency domain received signal by converting the received signal of the corresponding time domain into the frequency domain using a fast Fourier transform, and obtains the frequency domain received signal, estimated channel information, and The data transmitted through the data symbol is demodulated from the frequency domain received signal with reference to the data pattern transmitted through the data symbol from the transmitter.

As such, the data demodulation device according to an embodiment of the present invention receives a received signal for a data symbol having the same absolute value at a constant period of a time domain index in the time domain, and does not generate impulsive noise among the received received signals. By frequency-converting the received signal in the untimed time domain and demodulating the data transmitted through the corresponding data symbol, it is possible to prevent the problem caused by the impulsive noise by eliminating the influence of the impulsive noise, and furthermore, By minimizing the effects of noise, system performance can be improved.

6 is a flowchart illustrating an operation of a data demodulation method according to an embodiment of the present invention.

Referring to FIG. 6, in the data demodulation method, after performing synchronization and automatic gain adjustment on a received signal received by a receiver and performing channel estimation, a signal corresponding to a data symbol for transmitting data is received (S610).

In this case, the received signal corresponding to the data symbol may be represented by Equation 1, and impulsive noise may be included in a predetermined region of the received signal.

A received signal having a plurality of time domain indices corresponding to the data symbols is divided into a plurality of groups. The received signal is obtained by repeating the same absolute value when the transmitter allocates data to the data symbols and converts the data symbols into the time domain. Using a predetermined period is separated into a plurality of groups (S620).

For example, if a data symbol converted from a transmitter to a time domain is repeated with the same absolute value every N / 2 periods in the entire time domain index (N) of the data symbol, two groups are included such that the received signal includes N / 2 time domain indexes. To separate. That is, the received signal is divided into groups of data symbols as many times as the same information is repeated in the time domain.

When the received signal is divided into a plurality of groups, a signal quality value Q for each of the plurality of groups is calculated (S630).

In this case, the signal quality value can be calculated by the above formula (Equation 2), and this signal quality value is impulse because the value can vary greatly depending on whether the corresponding group includes impulsive noise Can be used as information to determine whether or not to include sex noise.

The signal quality value calculated for each of the plurality of groups is used to determine whether the normal group does not include impulsive noise or the abnormal group including impulsive noise for each of the plurality of groups (S640).

Here, a method of determining a normal group and an abnormal group using signal quality values may vary, and examples thereof will be described with reference to FIGS. 7 and 8.

When it is determined that each of the plurality of groups is a normal group and an abnormal group, the abnormal group is restored using the normal group (S650). In other words, since the same information is repeated in the same time domain in the time domain, the data symbol may restore the abnormal group to the normal group by copying the normal group to the abnormal group.

In this case, when there are a plurality of normal groups, it is preferable to restore an abnormal group by using a group having a minimum signal quality value among the normal groups.

The received signal from which the abnormal group is restored by the normal group is converted into the frequency domain using the FFT, and the data transmitted through the data symbol is demodulated using the received signal converted into the frequency domain and the data transmission pattern of the data symbol ( S660, S670).

Of course, when the estimated channel information is required for data demodulation, the data symbol converted to the frequency domain is obtained using the received signal and the estimated channel information converted into the frequency domain, and the data is obtained using the obtained data symbol and the data transmission pattern. Can be demodulated.

In addition, although the demodulated data is recovered using all groups of the received signal after restoring the abnormal group using the normal group in FIG. 6, the data is demodulated using only the normal group determined to be normal among the groups of the received signal. You can also demodulate.

FIG. 7 is a flowchart illustrating an embodiment of operation S640 shown in FIG. 6.

Referring to FIG. 7, step S640 detects a minimum signal quality value among the plurality of signal quality values calculated by step S630 and compares the detected minimum signal quality value with another signal quality value (S710 and S720).

In operation S730, it is determined whether the other signal quality value is equal to or less than a predetermined multiple of the minimum quality value through the comparison of the operation S720.

In this case, the constant multiple of the minimum quality value may be set in consideration of data demodulation performance and system performance.

As a result of comparing the remaining signal quality values with a constant multiple of the minimum quality value, if the remaining signal quality values are less than or equal to the multiple of the minimum quality value, the group is judged as a normal group without impulsive noise, and the minimum quality value. If it has a value exceeding a predetermined multiple of, it is determined as an abnormal group including impulsive noise in the corresponding group (S740 and S750).

For example, assuming that the plurality of signal quality values are Q1, Q2, Q3, and Q4, Q1 is the minimum signal quality value and the constant multiple is 1.6, by comparing the magnitudes of 1.6 × Q1 and Q2, Q3, Q4, respectively, It may be determined whether the group corresponding to Q2, Q3, and Q4 is a normal group or an abnormal group.

In this case, the predetermined multiple for determining the normal group and the abnormal group may vary depending on the situation, and the normal group and the abnormal group may be determined using two or more preset multiples instead of one constant multiple. Various decisions can be made.

8 is a flowchart illustrating another operation of step S640 illustrated in FIG. 6.

Referring to FIG. 8, step S640 calculates a ratio of two signal quality values to be compared by comparing the plurality of signal quality values calculated by step S630 (S810 and S820).

For example, assuming that the plurality of signal quality values are Q1, Q2, Q3, Q4, Q1 / Q2, Q2 / Q1, Q1 / Q3, Q3 / Q1, Q1 / Q4, Q4 / Q1 can be calculated and Q2 / Q3, Q3 / Q2, Q2 / Q4, Q4 / Q2, Q3 / Q4 and Q4 / Q3 may be additionally calculated.

When both ratios of the signal quality values are calculated, it is determined whether the calculated ratio is greater than or equal to the reference threshold by comparing each of the calculated ratios with a predetermined reference threshold Th (S830).

As a result of the determination in step S830, if the calculated ratio is equal to or greater than the reference threshold value, it is determined that either of the two groups includes impulsive noise, and a group corresponding to the two signal quality values larger is determined as an abnormal group, The corresponding group is determined to be a normal group (S840).

On the other hand, if the calculated ratio is less than the reference threshold as a result of step S830, it is determined that both groups corresponding to the two signal quality values as a normal group (S850).

Of course, only two values calculated by the two signal quality values, for example, Q1 / Q2 and Q2 / Q1, are determined to be normal groups only when both groups corresponding to Q1 and Q2 are less than the reference threshold.

6 to 8, in the data demodulation method according to an embodiment of the present invention, a time domain range in which the same information is repeated when a transmitter transmits a data symbol corresponding to a data symbol received through a power line Detach the groups into two groups, determine whether each of the separated groups contains impulsive noise, detect a normal group that does not contain impulsive noise, and then transform the normal group into frequency-domain transforms. By demodulating, problems that may be caused by impulsive noise may be solved, thereby improving performance of a communication system.

Furthermore, after demodulating the abnormal group containing impulsive noise using the normal group as necessary, the demodulated data is demodulated by frequency domain transforming the received signal from which the abnormal group is restored and demodulating the data transmitted through the corresponding data symbol. May be further improved.

The multi-carrier based data demodulation method and apparatus for reducing the influence of impulsive noise according to the present invention can be modified and applied in various forms within the scope of the technical idea of the present invention, and are not limited to the above embodiments. In addition, the embodiments and drawings are merely for the purpose of describing the contents of the invention in detail, not intended to limit the scope of the technical idea of the invention, the present invention described above is common knowledge in the technical field to which the present invention belongs As those skilled in the art can have various substitutions, modifications, and changes without departing from the spirit of the present invention, it is not limited to the embodiments and the accompanying drawings. And should be judged to include equality.

1 shows an example for measurement based impulsive noise.

2 shows a communication system for explaining a data demodulation device according to an embodiment of the present invention.

3 shows a multi-carrier based packet structure.

FIG. 4 illustrates an embodiment configuration of the receiver shown in FIG. 2.

5 shows a configuration of a data demodulation device according to an embodiment of the present invention.

6 is a flowchart illustrating an operation of a data demodulation method according to an embodiment of the present invention.

FIG. 7 is a flowchart illustrating an embodiment of operation S640 shown in FIG. 6.

8 is a flowchart illustrating another operation of step S640 illustrated in FIG. 6.

<Description of Symbols for Main Parts of Drawings>

510: separation

520: calculation unit

530: the judgment unit

540: demodulator

Claims (11)

A multi-carrier based data demodulation method for demodulating data from a received signal corresponding to a data symbol having a same absolute value at a predetermined period of a time domain index in a time domain, Dividing the received signal into a plurality of groups including the time domain index of the predetermined period; Calculating signal quality values for each of the plurality of groups; Determining a group having a signal quality value equal to or less than a preset multiple compared to the minimum signal quality value as compared with the minimum signal quality value among the signal quality values for the plurality of groups as a normal group; And Converting at least one normal group determined to be normal into a frequency domain and demodulating data transmitted through the data symbol at a transmitter; Data demodulation method comprising a. delete The method of claim 1, The demodulating step Data demodulation for restoring an abnormal group determined to be abnormal by the determining step using the normal group, converting the received signal from which the abnormal group is restored to a frequency domain, and demodulating data transmitted through the data symbol. Way. The method of claim 3, The demodulating step And demodulating the abnormal group using the group having the minimum signal quality value. The method of claim 1, The calculating step And calculating the signal quality value by summing all absolute values of a received signal corresponding to a time domain index constituting the group. The method of claim 1, The determining step Comparing each of the signal quality values for the plurality of groups, it is determined whether the ratio of the two signal quality values to be compared is equal to or greater than a preset reference threshold value. A method of demodulating data that determines a small group of values as a normal group. The method of claim 6, The demodulating step Data demodulation for restoring an abnormal group determined to be abnormal by the determining step using the normal group, converting the received signal from which the abnormal group is restored to a frequency domain, and demodulating data transmitted through the data symbol. Way. A multi-carrier based data demodulation device for demodulating data from a received signal corresponding to a data symbol having a same absolute value at a predetermined period of a time domain index in a time domain, A separation unit for dividing the received signal into a plurality of groups including the time domain index of the predetermined period; A calculator for calculating signal quality values for each of the plurality of groups; A determination unit which determines a group having a signal quality value equal to or less than a preset multiple compared to the minimum signal quality value as a normal group by comparing with the minimum signal quality value among the signal quality values for the plurality of groups; And A demodulator for converting at least one normal group determined to be normal into a frequency domain and demodulating data transmitted through the data symbol at a transmitter Data demodulation device comprising a. delete The method of claim 8, The demodulation unit A data demodulation device for restoring an abnormal group determined by the determination unit by using the normal group, and converting the received signal from which the abnormal group is restored to a frequency domain to demodulate data transmitted through the data symbol . The method of claim 8, The determination unit Comparing each of the signal quality values for the plurality of groups, it is determined whether the ratio of the two signal quality values to be compared is equal to or greater than a preset reference threshold value. A data demodulation device for judging a small value group as a normal group.

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